NATIONAL BUREAU OF STANDARDS

^ccUntcal ^ote 197

ISSUED SEPTEMBER 23, 1963

RESEARCH ON CRYSTAL GROWTH

AND CHARACTERIZATION AT THE

NATIONAL BUREAU OF STANDARDS

DURING THE PERIOD JANUARY TO JUNE 1963

Edited by H. Steffen Reiser National Bureau of Standards

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

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Contents

Page

Introduction ---------------------------------- 1

Crystal Growth --------------------------------- 2

2. 1. High-Temperature Crystal Growth ----------------____ 2

2. 2. Crystal Growth and Structure Studies ------------------ 3 2.3. The Growth of Dislocation-Free Metal Crystals from the Melt ------ 3 2.4. Kinetics of Growth of Crystals from the Melt -------------- 3 2.5. Crystal Growth from Solution ---------------------- 4

2.6. The Crystallization of Polymers from Concentrated Solutions ------ 4

2.7. Crystallization of Polyethylene Fractions ------------___ 7 2.8. Homogeneous Nucleation in Polymer Crystallization ----------- 8 2.9. Vapor-Phase Growth Kinetics of Metal Crystals ------------- 8

2. 10. Crystal Growth by Electrodeposition ------------------ 8

2. 11. Stress-Induced Martensitic Transformations --------------- 8

2. 12. Radio-Materials Synthesis ----------------------- 9

2. 13. Thermal Etching of Crystalline Argon ------------------ 9

2. 14. Whisker Growth of Rare Gases ---------------------- 11

2. 15. Kinetics of Whisker Evaporation -------------------- 11

2. 16. Theoretical Studies in Whisker Crystal Growth ------------- n

2. 17. Growth Kinetics of Crystal Whiskers by Field-Emission Techniques - - - - 12

2. 18. Field Emission Studies ------------------------- 12

2.19. Studies of Small Crystals of Nickel and Nickel Halides --------- 12

2. 20. Growth of Oxide Films on Aluminum Single-Crystal Surfaces ------- 13

2. 21. Thermal Evaporation from (OOOl} Zinc Surfaces ------------- 13

Defect Characterization ---------------------------- 15

3.1. Studies of Crystal Defects ----------------------- 15 3.2. Defects in Thin Oxide Films -----______---- 15 3.3. Surface Structure of Vapor-Grown Crystals --------------- 15

3.4. Surface Behavior of Copper Single Crystals in Fused Sodium Chloride - - 16

3.5. The Effect of Point Defects on the Dynamic Properties of Crystals - - - 16

3.6. Precision Measurement of the Fundamental Electrical Properties of

Semiconductor Crystals ------------------------- 16 3.7. Soft X-Ray Spectroscopy of the Solid State --------------- 18

3.8. Spectroscopy Applied to Crystal Growth ----------------- 19 3.9. Improved Sources for Spectrographic Analysis -------------- 19

3. 10. A Laser Microprobe for Analysis of Very Small Samples --------- 19

3. 11. Optical-Property Studies ------------------------ 21 3.12. Optical Properties of "Pure" and Impure Crystals ------------ 21

3.13. Automation of Single-Crystal X-Ray Diffraction Intensity Measurements - 21 3.14. High-Voltage Laue Photographic Inspection of Large Single Crystals - - - 23

3. 15. Dilatometric Studies of Polymers -------------------- 23

Crystal Physical Properties -------------------------- 23

4. 1. Velocity of Sound in Ice Single Crystals ---------------- 23

4. 2. Electronic Transport -------------------------- 24

4.3. Hall-Effect Measurements ------------------------ 24

4.4. Dielectric Constant and Losses --------------------- 25

4.5. Electron-Lattice Interaction ---------------------- 25

4.6. Studies in Solid-State Theory --------------------- 25

4.7. Isotopic Impurities and Energy Transport in Harmonic Crystals ----- 26

4.8. Cryomagnetic Theory -------------------------- 26

4.9. Energy Transfer Below 1°K ------------- - 26

4.10. Low-Temperature Nuclear Orientation ------------------ 27

4. 11. Low-Temperature Thermometry ---------------------- 27

11
Page

4. 12. Nuclear-Resonance Thermometry --------------------- 27 4.13. Metal-Oxide Melting-Point Standards ------------------ 27

4. 14. Reduction of Space Groups to Subgroups by Homogeneous Strain ------ 28

4. 15. Magnetic-Susceptibility Measurements ------------------ 28

4. 16. Magnetic-Resonance Studies I---------------------- 28

4. 17. Magnetic-Resonance Studies II --------------------- 30

4. 18. Microwave Measurements on Single-Crystal Ferrimagnetics -------- 30

4. 19. Work Function of Perfect Single-Crystal Planes of Tungsten ------- 31

4. 20. Interaction of Low-Energy Particles with Surface Atoms --------- 31

4. 21. Molecular Energy Levels ------------------------ 31

4. 22. Crystal-Field Studies by Matrix Spectroscopy -------------- 31

5. Crystal Chemistry ------------------------------- 32

5. 1. Phase Equilibria ---------------------------- 32

5.2. Crystal-Structure Analysis ----------------------- 32

5.3. Standard X-Ray Diffraction Powder Patterns --------------- 32

5.4. Rapid X-Ray Diffraction Photography of Polycrystalline Materials - - - - 33

5.5. Application of Borrmann Crystals to the Construction of a HighResolution Small-Angle X-Ray Camera ------------------ 33

5.6. Lattice Parameters and Energies of High-Pressure Polymorphs of Some

Alkali Halides - 33

5. 7. Infrared Spectroscopy of Crystalline Inorganic Borates --------- 33

5.8. Optical Observations of Pressure-Induced Transitions in Polymers - - - - 34

5.9. High-Pressure Microscopy of Crystal Transformation and Growth ----- 34

5. 10. Purification of Polymorphic Inorganic Solids and Preparation of Crystals

of a Single Polymorphic Species -------------------- 34

5. 11. Crystal Chemistry of Silver Iodide ------------------- 35

5. 12. Phase Equilibria in Dilute Polyethylene-Diluent Systems -------- 35

5.13. The Structure of Silica Whiskers -------------------- 36

5. 14. Structure Models for Amorphous and Crystalline Phases of Simple

Substances ------------------------------- 36

5. 15. Radial-Distribution Studies of Glasses ----------------- 36

6. Partial List of Participants -------------------------- 35

7. Literature References ----------------------------- 41

RESEARCH ON CRYSTAL GROWTH AND CHARACTERIZATION

AT THE NATIONAL BUREAU OF STANDARDS

DURING THE PERIOD JANUARY TO JUNE 1963

Edited by H. Steffen Peiser

Abstract

The National Bureau of Standards with partial

support from the Advanced Research Projects Agency

is continuing diverse research projects on the growth

and characterization of crystals. This note summarizes the individual NBS activities in this and closely

related fields during January to July 1963. Lists of

NBS publications appertaining to that period and of

participating NBS scientists are appended.

1. INTRODUCTION

This is the second biannual collection of brief statements on research in progress at the National Bureau of Standards on crystal growth and characterization. In the previous

collection the general purpose, background, and program area have been described (see NBS

Technical Note 174 issued on March 15, 1963). Much of the research now summarized has

again been supported directly from NBS funds, but an increasing proportion has been financed by transferred funds from the Advanced Research Projects Agency. This assistance from

ARPA has made a great deal of difference, especially in encouraging the rapid expansion of

promising projects. This help is hereby gratefully acknowledged, but in the text no attempt

has been made to single out the particular portions of the work that have been ARPA supported. Only where other agencies have made additional funds available a separate acknowledgment is given.

The research statements have been edited and assembled with the invaluable help of

assistant editors from the NBS organizational divisions as follows:

Electricity: J, D. Hoffman

Heat: J. F. Schooley

Analytical and Inorganic Chemistry L. J. Frolen

Mechanics: R. S. Marvin

Polymer: E, Passaglia

Metallurgy: R, L. Parker

Inorganic Solids: F. A. Mauer

Atomic Physics: H. P. R. Frederikse

Instrumentation: J. C. French

Physical Chemistry: D. E. Mann

The collaboration of the NBS Boulder Laboratories is greatly welcomed. Mrs. E. Burnette and Miss R. M. Delaney have also helped in the assembly of the material. B. Paretzkin assisted in the selection and preparation of figures.

The decisions regarding inclusion or exclusion of statements from the diverse re- search projects have been left to the discretion of project leaders, division editors, and

division chiefs, but in general encouragement has been given to participate in the writing

of this report even where such critical border subjects are involved as crystal-surface

studies, crystal-phase equilibria, crystal-structure determinations, etc. The program area

delineated by this report is therefore slightly wider than that defined in NBS Technical

Note 174 Section 3,
The summaries are now grouped into four sections as follows:- Crystal Growth^ Defect

Characterization, Crystal Physical Properties, and Crystal Chemistry. The areas covered

are defined at the beginning of each section. Many individual statements might well have

fitted into more than one of these broad categories. The order within sections has not

been logically justified. It is indeed a good feature of the crystal program at NBS that

the cross-links between projects are so numerous that there can be no completely satisfactory order of presentation.

The ARPA "Crystal Group" at NBS has sponsored a number of activities during the first

half of 1963. There have been monthly evening colloquia on specific topics. Many well

attended colloquia have also taken place to mark visits of crystal scientists from other

research institutes. To a symposium on the general topic of "Research Programs in Crystal

Growth and Defect Characterization" NBS and ARPA invited about seventy scientists from many

U. S. laboratories. NBS scientists have visited and corresponded with many other interested

laboratories.

Thus the NBS "Crystal Group" by individual effort coupled with good collaboration aims

to contribute significantly to a field of science that presents many opportunities for fundamental progress. No one doubts the importance of the technological advances that ultimately will follow such progress.

2. Crystal Growth

Contributions to this section are concerned

with mechanisms and techniques of crystal

growth and dissolution of single crystals.

2. 1. High-Temperature Crystal Growth

W. S. Brower and F. Ordway,

Crystal Growth Section

The primary purpose of this project is to investigate the influence of growth parameters on the perfection of refractory oxide crystals with the ultimate aim of developing

techniques for growing more nearly perfect crystals of high-melting compounds as typified

by rutile, TiO_; sapphire, A1_0. ; Ci„0 ; and stabilized ZrO„.

Temperature measurements have been made using Ir-IrRh thermocouples while growing

crystals of sapphire by the Verneuil process. Measurements are now being made incorporating some refinements of technique.

Crystals of rutile grown at widely varying rates are being examined by the etch technique to determine the effect of growth rate on the character of the sub-grain boundaries

and the average dislocation densities.

A new flame-fusion burner was designed which will permit the use of acetylene or acetylene-hydrogen mixtures, thus extending the temperature range of the conventional flamefusion assembly.

A high-frequency RF generator (30 - 150 Mc) has been purchased. It will be used both

in attempts to grow crystals of some of the oxides using direct coupled RF power, and as the

power source for the inductively coupled plasma torch. The machine will be incorporated

into the present program and the crystals produced will be evaluated with respect to those

produced by other methods.

* This work was principally supported by the Atomic Energy Commission.
2. 2. Crystal Growth and Structure Studies

D. E. Roberts and M. I. Cohen,

Solid State Physics Section

The emphasis has been on the growth of cadmium telluride, CdTe, crystals. First the

elements are reacted; this process is complicated by the high heat of reaction and by the

high vapor pressure of the components. Subsequently the compound is melted into one end of

a tube; the dead space is filled with a quartz plug before sealing the tube at the other

end. (This method originally described by Lorenz and Halsted of the General Electric

Laboratories maintains the stoichiometry of the compound. ) After lowering the tube through

a heated zone an ingot is obtained which contains single crystals as large as 1 cm across. So far all ingots prepared in this way are p-type.

The growth of rutile, TiO„, crystals by the Verneuil technique is continued; boules

with one of about 15 different doping agents have been prepared.

A large portion of the effort has been expended on orientation studies of crystals,

among them TiO , SrTiO , spinel, PbF , MnF^, KN , a -'Ee^O , and PbS.

Samples of TiO„ that had been subjected to uniaxial pressures of 50 kbars and 100 kbars were examined. No changes could be detected.

The variable-temperatures (range -175°C to about 2100°C) attachment for the X-ray

dif fractometer has been installed and preliminary tests made.

2.3. The Growth of Dislocation-Free Metal

Crystals from the Melt

T. H. Orem, Metal Reactions Section;

R. L. Parker and H. C. Vacher,

Metal Physics Section

For background see the description in NBS Technical Note 174 Section 4.3. The crystal

puller has been received and put into operation. A suitable power supply, temperature control, and gas supply were set up. Several aluminum crystals were pulled from 5-9 purity

aluminum, in a helium atmosphere. By suitable control of melt temperature and pulling

speed, Al single crystal rods less than 1 mm in diameter were grown. The seeds used had

been grown by the Bridgman technique. Laue back-reflection X-ray photographs showed that

the pulled crystals had fewer imperfections than the seed crystals. High-voltage Laue

transmission studies were also made.

A Rigaku-Denki microfocus X-ray diffraction unit has been put into operation in co- operation with the Physical Properties Section. The Lang camera for this unit has not yet

arrived. Preliminary studies have been started using divergent -beam methods (pseudo-Kossel

lines).

2.4. Kinetics of Growth of Crystals from the Melt

J. G. Early and R. L. Parker,

Metal Physics Section

For background see the description in NBS Technical Note 174 Section 4.4. Visits to

Drs. Tiller and Kramer at Westinghouse Research Laboratories have been made and plans to

set up apparatus similar to theirs are proceeding. It was learned that their method

[described theoretically in J. Chem. Phys. 37, p. 841 (1962)] has provided measurements of

interface temperature in the growth of metal crystals from the melt.
2.5. Crystal Growth from Solution

J. L. Torgesen, A. T. Horton, and J. Strassburger^

Crystal Chemistry Section

The objectives of this project (see also NBS Technical Note 174 Section 4.5) concern

(a) the development of crystallization techniques for the growth of large single crystals

and the preparation of single-crystal specimens of inorganic and organic substances; (b)

studies of the properties of single crystals, both those of high purity and those containing selected impurities, by appropriate physical and chemical methods; and (c) basic

research relating to the mechanisms of crystal growth and impurity retention.

Single-crystal growth from aqueous solution by temperature -program techniques has con- tinued the production of specimens of ammonium dihydrogen phosphate (pure and containing

chromium impurity), sodium chlorate (pure and containing copper impurity), sodium nitrate,

and potassium chloride. Individual recorders, presently on order, are to be incorporated

and an automatic warning system for temperature-control failure will be included.

With some revisions of a design proposed by Karpenko, et al. [Sov. Phys. Cryst. §_, No. 1, 120 (1961)], apparatus for the growth of single crystals from solution by evaporation

and circulation of the solvent has been constructed. The equipment is to be used for

crystal growth at constant temperature and is expected to be particularly effective for

those substances having low temperature coefficients of solubility. Experiments on the

adequate control of temperature are in progress.

Solvent effects on the growth of large single crystals from solution have been strikingly illustrated in experiments with oxalic acid. The anhydrous acid crystallizes from

glacial acetic acid solution to give single-crystal specimens of inferior quality containing inclusions of mother liquor. The addition of small amounts of water to the solvent

promotes the growth of single crystals of greatly improved quality. A phase study of the

system oxalic acid/acetic acid/water at 50°C has shown anhydrous oxalic acid to be the

stable solid phase in equilibrium with acetic acid/water solutions containing up to 5. 2 precent water (J. Strassburger and J. L. Torgesen, 1963).

Good single crystals of oxalic acid dihydrate are difficult to grow from water solution.

Inferior specimens, growing primarily by deposition on {^OOlJ- with a resultant habit in

which {lOl} and {llO} predominate, are cloudy with inclusions of mother liquor. Growth from

solution in acetone/water mixtures produces specimens with marked improvement in crystal

quality. Deposition occurs primarily on {llO} . The habit becomes increasingly prismatic

at higher acetone concentrations with {OOl} , {lOl} , and {llO}- predominating. Details of

these studies on oxalic-acid crystal growth will be submitted for publication.

Other steady-state diffusion processes for the growth of single crystals of sparingly

soluble salts have been abandoned in favor of growth in silica gel. Although initial ex- periments have been confined principally to a duplication of conditions described by Holmes

[J. Franklin Inst. 184, 743 (1917)], some effects of gel acidity, and the nature and con- centration of reacting and foreign ions have been observed. Successful results have been

obtained with lead iodide (hexagonal platelets 4-5 mm wide and 1 mm thick), copper tartrate

(well-developed habit, 3 mm long and 1/2 mm in diameter), and calcium sulfate dihydrate

(gypsum). Small crystals of mercuric iodide, silver dichromate, and lead chromate have been

grown, but little success has been achieved with silver halides.

Completely satisfactory results have not been obtained in the preparation of thin

sections of water soluble substances for dislocation studies by etching and X-ray diffraction

microscopy. The most promising final step in surface preparation appears to be a general

"chemical" etch by agents having low to moderate solvent action,

2.6. The Crystallization of Polymers from Concentrated Solutions

F. Khoury, Polymer Physics Section

It is well established that crystallization in the spherulitic form occurs most
Figure 1. Individual polypropylene spherulites grown from a 107o solution of

the polymer in xylene. The spherulites are shown as seen after evaporation

of the solvent. (Unpolarized oblique incident illumination x 400).

Figure 2. Three dimensionally asjmimetric

aggregates of polypropylene grown from a

0. 757o solution of the polymer in paraffin

oil. Aggregate is in suspension in solvent

and is dipicted as seen oriented such as to occupy a maximum surface area in the field

of the microscope. (Unpolarized light x 2000).

Figure 3. Sheaflike appearance which is

characteristically seen when an aggregate of

the type shown in figure 2 is rotated from

the orientation depicted in that figure

through 90° about any axis in the plane of

the microscope stage. (Unpolarized light x

2000).
Figure 4. Spherulite of polyhexamethylene adipamide (66 nylon) grown from a

107o solution of the polymer in glycerol. The spherulite is in suspension in

the solvent. (Crossed Nicols x 1500).
commonly when synthetic polymers are crystallized from the melt. Much attention has been

directed in recent years to the determination of the morphology of polymer spherulites. In view of the inaccessibility of the latter aggregates in bulk polymer most investigations

have been confined to a study of spherulites formed in thin polymer films. By essentially

restricting the growth of the spherulites to two dimensions within the plane of these films,

and subsequently replicating the surface of the films for examination under the electron

microscope, a cross-sectional rendition has been obtained of the morphology of spherulites

of various polymers.

In order to elucidate further the mechanisms of growth of polymer spherulites, one would wish to supplement such studies as have been mentioned above by an investigation of

the surface morphology of spheirulites (quenched at various stages of development) whose

growth from the melt has not been restricted by sample geometry. The experimental barriers

to such a study would be overwhelming, if not insurmountable.

During the course of a recent investigation of the crystallization of polypropylene

from hot, moderately concentrated solutions (l-107o) of the polymer in various solvents

(e.g. xylene, decalin, paraffin oil) it has been found that, on cooling, such solutions

yield polymer spherulites in suspension in the solvent (Fig. 1). By varying the concen- tration of polymer, the solvent used, or the rate of cooling, spherulites have been

obtained which exhibit different signs of radial birefringence and apparent coarseness of

internal texture.

Under certain circumstances, in particular on crystallization of polypropylene from

mineral oil, individual polymer solutions have been found to yield in addition to spherulites a variety of crystalline aggregates which exhibit three-dimensionally asymmetric growth

patterns- they thus present distinctly different appearances when viewed under the optical

microscope, depending on their orientation in the field of view. An example typical of many

such asyinmetric aggregates is shown in figure 2. Characteristically, when they are oriented

so as to occupy a maximum surface area in the field of view of the microscope, they exhibit

a roughly elliptical shape, as may be seen in figure 2. If, however, they are rotated from

this position through 90° about an axis in the plane of the microscope stage they appear

sheaf like in shape (Fig. 3). The nature of the fine structure of these and other related

types of asymmetric aggregates which have been observed is as yet unknown. Replicating

techniques in conjunction with electron microscopy will be applied to determine in detail

the nature of their morphology and associated growth processes. Although their various

asymmetric structures are in themselves of interest they are also of further interest since

it has been found that their various habits are similar to those of the successive structures

which develop during the early stages of growth of individual spherulites from polypropylene

solutions in paraffin oil. Briefly, therefore, conditions have been found which yield polypropylene aggregates in suspension in solvent which are representative of the various stages

of growth of polymer spherulites. These various aggregates can be readily isolated and

replicated for electron microscopy. Such an investigation should provide detailed information on the mechanism of growth (e. g. the role played by crystal imperfections and non- crystallographic branching) of spherulites from solution which would also be pertinent to

a better understanding of the formation of spherulites in bulk polymer when it is crystallized from the melt.

Similar studies are being extended to other polymers, in particular 6-nylon and 66-

nylon which we have recently crystallized from solution in the form of spherulites (Fig. 4)

as well as sheaf-like aggregates.

2. 7. Crystallization of "Polyethylene Fractions

R. C. Neuman, Dielectrics Section

and J. Powers, Macromolecules Synthesis and Structure Section

The morphology of polyethylene fractions with a molecular weight between 1800 to 1.4 x

10" was examined over a range of crystallization temperatures from 100°C to 131°C. A densely granulated field usually resulted for most fractions at most temperatures. For a few

samples ringed spherulites were discerned in the crystallization temperature range from
100°C to 115°C, but these appeared too rapidly (20-30 sec) for measurements of their growth

rate to be made. The ring spacing was found to increase with increasing crystallization

temperature. These samples melt at temperatures from 126°C tol28°C, well below the usual

polyethylene melting temperature of 136°C to 138°C. Subsequent crystallization in the

temperature range 127°C to 131°C produced a granulated field. The variables studied included temperatures above the melting point at which the sample was melted, temperatures

of crystallization, and whether the sample was melted and crystallized on the Kofler hot

stage, or in silicone-oil baths. The high nucleation rate indicates polyethylene is wetted

by a number of heterogeneous nuclei, such as cellulose. Some samples, cleaned by precipitation techniques, showed no differences in structure or growth rate from uncleaned samples,

2.8. Homogeneous Nucleation in Polymer Crystallization

F. Gomick, Macromolecules Synthesis and Structure Section;

Lois Frolen and Gaylon Ross, Pure Substances Section

Precise measurements of homogeneous -nucleation rate constants is desired in order to test and enlarge upon existing theories relating such constants to other measurable properties of polymers and other materials. The most effective means of obtaining truly homogeneous nucleation rates is by the droplet method, i.e., by subdividing a purified liquid

into droplets small enough that most of them will be free of nucleation catalysts. The

temperature coefficient of nucleation of these droplets is then measured. In polyethylene

it is desired to measure the nucleation rate over a very wide temperature range. Apparatus

for the production of spherical droplets of purified fractions of polyethylene is under

development. The apparatus has been designed to produce droplets ranging from one to ten

microns in diameter. Special microscope accessories such as ultra-long range objectives

and a hot stage with precise temperature -measurement capability are under design. This

equipment will permit the measurement of nucleation rates of polyethylene under isothermal

conditions, this system having been studied by other investigators under non-isothermal

conditions. The studies can be extended to other substances, such as a group of well

purified di-phenyl alkanes that are available.

2.9. Vapor-Phase Growth Kinetics of Metal Crystals

R. L. Parker, Metal Physics Section

For background see the description in NBS Technical Note 174 Section 4. 8.

The mass spectrometer has been ordered but not yet received. Part of the present

apparatus has been used in experiments described in 4. 16.

2.10. Crystal Growth by Electrodeposition

F. Ogburn, Electrolysis and Metal Deposition Section

For background see the description in NBS Technical Note 174 Section 4.9.

X-ray examination by the Buerger and Weissenberg methods has shown 5-fold symmetry,

of copper dendrites grown electrolytically, about the growth axis parallel to [110]. This

is thought to be due to a series of twins in the dendrite. In another set of dendrites of

Cu, optical metallographic examination showed pairs of twin planes extending through

dendrite branches, indicating that twinning may play a role in branching. Lead dendrites

have been grown electrolytically and are being examined.

2. 11. Stress-Induced Martensitic Transformations

R. P. Reed and C. J. Guntner,

Cryogenic Engineering Laboratory

A commercial 18% chromium-87o nickel iron alloy was examined in tension at 300, 76, 20,

and 4°K. Continuous stress-strain recordings were made. X-ray analyses at periodic stress
(strain) intervals were obtained, and magnetic measurements were taken. From this data the

percentages of martensitic products (BCC, , and HCP, .) were computed as a function of

stress (strain).

It was found that up to 157o 6 phase forms at low temperatures. The amount of £ formed

increases to about 57=, strain, then decreases. This decrease indicates the additional transformation of € to a'. The total amount of € and a' was suppressed at constant stress

(strain) at 4°K as compared to that at 76°K. It is proposed that the suppression of £

and a' is associated with the decreased mobility of extended dislocations at very low

temperatures. The yield strength decreased as the temperature was depressed below room

temperature and then increased rapidly near 4°K.

2. 12. Radio-Materials Synthesis

P. M. Gruzensky,

Radio and Microwave Materials Section

Efforts to determine the optimum conditions for synthesis of anhydrous copper sulfate

and zinc sulfate doped with copper have continued during this report period. A sulfuric

acid-ammonium sulfate mixture has been used as solvent, as reported previously, and offers

some advantages over the separate components. Some preliminary experiments indicate that

the crystal habit can be changed by adding a small amount of an alkali metal sulfate to the solvent. Additional experiments are indicated and will continue.

The low nuclear magnetic moment, as well as the trigonal structure, of calcite make

it of interest as a host structure for paramagnetic ions in resonance studies. Unfortunately, to date sizeable crystals of this material have defied synthesis and only those

paramagnetic impurities which exist in natural calcite specimens have been examined.

Experiments in this laboratory have been concentrated on synthesis by a slow diffusion of

carbonate ion through a solution containing a calcium salt. Optical-quality rhombs with

edge dimensions up to 1 mm have been obtained in this way but obvious flaws develop as the

crystals grow larger. In future work, considerable attention will be given to the purification of starting materials in an effort to reduce the number of nucleation centers.

It is anticipated that the synthesis of lead sulfide single crystals will be given some consideration in the future. Artificial crystals of this material have been prepared by

others using the Bridgman technique, but these crystals deviate from stoichiometry as a result of partial decomposition at the high temperatures involved. A crystal-growth

technique at lower temperatures would be a contribution in the study of intrinsic properties in PbS.

2. 13. Thermal Etching of Crystalline Argon

G. L. Pollack and E. N. Farabaugh,

Crystal Growth Section

Reliable experimental tests of many theoretically predicted properties of solid rare

gases can best be made on large single crystals. By successive freezing from the melt, a modified Bridgman method, crystals of argon have been grown near the triple point with

about centimeter dimensions as revealed by thermal etching (Pollack and Farabaugh, 1963).

Techniques of growth and etching at different temperatures and pressures have been developed

and investigated. Crystal-growth rate and size have been examined as functions of temperature gradient, supersaturation, and chamber geometry, and have been related to modern

theories. Interesting comparisons can be drawn between the mechanism of thermal etching

in a system of low surface energy and high triple-point vapor pressure, such as crystalline

Ar, and the same process in metals which has been studied often. Many surprising details

on the crystal surfaces have been observed; striations and what may be rosettes have been

examined. Experiments which were not possible before are now practical with these crystals

and are being investigated. The techniques of crystal growth and etching are being

extended to other rare gases and molecular solids.
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2. 14. Whisker Growth of Rare Gases

G. L. Pollack,

Crystal Growth Section

Preliminary experiments have been performed to determine the conditions under which

whisker growth of rare-gas crystals will occur and to measure properties of the whiskers.

Dendritic growth from the melt has already been observed and investigated (Pollack and

Broida, 1963a). Vapor-deposition studies at temperatures between 77°K and 20°K and at pressures from 0.5 atomosphere down to 10 microns have demonstrated the possibility of

growing whiskers from the vapor and measuring their length as a function of time. These

experiments are aimed at advancing theories of surface properties, and especially surface

mobilities, by looking at the prototype rare-gas solid surfaces.

2. 15. Kinetics of Whisker Evaporation

R. L. Parker, R. L, Anderson, and T, Wagner,

Metal Physics Section

For background see the description in NBS Technical Note 174 Section 4.16.

We have studied both the growth and the evaporation of potassium and mercury whiskers

and have found that the surface-diffusion equation can quantitatively account for many

aspects of both growth and evaporation in these systems. The whiskers are nucleated and

grow on silver or tungsten substrates in pure, supersaturated metal vapor in a sealedoff pyrex vessel, prepared by ultra-high-vacuum techniques. Direct optical measurements

of the whisker length as a function of time for various temperatures and supersaturations were made. Some two thousand photographs have been taken; figure 5 shows a typical sequence

for potassium whiskers.

From the surface-diffusion equation,

(1) D-^a -^+N=

^

x^ '^ dt

where x is distance from the whisker base, c the adatom surface concentration, N the incident vapor flux, D the surface diffusion coefficient, and 1/t the evaporation probability,

one obtains the following equation for the whisker length ^, assuming a steady-state growth

process and appropriate boundary conditions:

(2) -jr- = ^(N-No> T ^^-^ 4^

Here K is a known constant, r the effective whisker radius, N the equilibrium flux, and

X =^/D^ • This equation predicts, in the case of growth (N>N ), an initial exponential

increase in length, followed by a linear increase in length. We have observed both regions

optically on K and Hg whiskers, and have obtained X and r values for these whiskers. A

typical X value for K at 55°C is 60 microns. If now one takes the case of evaporation

(N < N ), the same equation (2) predicts, if the same mechanisms are operating during

evaporation as during growth, first a linear decrease in length and then an exponential

decrease. Again, we have observed both regions optically on K and on Hg whiskers

(R. L. Anderson and R. L. Parker, 1963). Further studies on these whiskers are continuing.

2.16. Theoretical Studies in Whisker Crystal Growth

J. S. Simmons, R. E. Howard, and R. L. Parker,

Metal Physics Section

and H. J. Oser, Computation Section

For background see the description in NBS Technical Note 174 Section 4. 17.

11
An implicit exact solution for the time-dependent surface-diffusion equation describing the general case of whisker growth with re-evaporation has been obtained. This solution

assumes that the surface concentration tends to zero near the whisker tip. It is hoped

eventually to remove this restriction.

Using the principle of conservation of mass, an auxiliary integral equation has been

obtained; it appears suitable for machine computation of the non-linear system governing

whisker growth. This computation procedure has been programmed and the program is currently being checked prior to a production run on the IBM 7090 computer.

Asymptotic solutions have been obtained for both short and long times. In this general case, for long times, the length becomes linear in time. Finally, the growth equations

can be dimensionalized so as to reduce the problem to a one-parameter family of curves governed by a reduced evaporation parameter T '

.

2. 17. Growth Kinetics of Crystal Whiskers by

Field-Emission Techniques

S. C. Hardy and R. L. Parker,

Metal Physics Section

Field-emission patterns of potassium whiskers taken during growth do not show the dark

areas corresponding to crystal planes of high work function which are usually seen with

other metals. We have tentatively attributed this to the sputtering and consequent roughening of the whisker tip by ions formed in the K vapor by electron impact. We have

obtained sjnnmetric patterns from K whiskers by reducing the vapor pressure to a low value

before application of the field. These patterns are characteristic of bcc emitters with

[110] orientation but do not display any fine structure.

Several F.E. tubes designed to study the heterogeneous nucleation of mercury on tungsten have been built.

2.18. Field-Emission Studies

W. J. Ambs and E. Escalante,

Metal Reactions Section

For background see the description in NBS Technical Note 174 Section 5.22.

The adsorption of oxygen at room temperature on a clean nickel surface has been found

to depend strongly on crystal face, showing considerable enhancement of emission on planes

close to |_110_} . Adsorption at 77°K shows no such phenomenon.

Preliminary experiments on iron show that iron whiskers can be grown by heating iron

field emitters to 900°C in the electric field. The phase transition at 910°C has also

been observed.

Experiments have been started on the growth and oxidation of magnesium films deposited

on tungsten. The purpose is to check the validity of proposed oxidation mechanisms involving "island nuclei."

2. 19. Studies of Small Crystals of Nickel and Nickel Halides

D. R. Winder, Radio and Microwave Materials Section

Nickel whiskers, nickel halide whiskers and platelets have been grown for studies of

dimensionality in magnetism. The conditions for growth of these crystals have been studied

and the growth characteristics of the platelet habit investigated. A paper by E. N. Sickafus and D. R. Winder on the last subject was presented at the Colorado -Wyoming Academy

12
of Science, May, 1963. The abstract follows:

"Hydrated crystals of NiBr2 have been grown in the relatively cool, downstream end of the whisker growth chamber during the growth of Ni whiskers by

the method of hydrogen reduction of the halide. These crystals are in the

form of platelets and very thin dendrites. The dendrites grow first and then

growth spirals occur on the dendrites which produce a heavy overgrowth and

usually cover up most of the original dendritic structure. The growth spirals

have relatively large steps (several hundred angstroms) and are easily resolved

with the optical microscope. Double beam interference patterns are presented

which have been made under monochromatic illumination."

2. 20. Growth of Oxide Films on Aluminum Single-Crystal Surfaces

T. H. Orem, Metal Reactions Section

For background see the description in NBS Technical Note 174 Section 4. 19.

In recent studies of the relationship between oxide film and substrate on aluminum,

the configurations of what are currently considered to be pits caused by vacancy condensation have been investigated. The pit edges are often parallel to traces of close-packed

planes in the surface in question. Pits in other crystallographic surfaces are being

investigated.

2. 21. Thermal Evaporation from ^^OOOlJ Zinc Surfaces

A. W. Ruff, Jr., Metal Physics Section

The purpose of this research was to investigate the surface structures developed

during thermal evaporation from freshly cleaved zinc single crystals. Particular attention

was devoted to the role of pre-existing surface steps, dislocations, surface impurities and

volume impurities. Typically, the surface to be studied was held at 300°C for 15 minutes

in different controlled vapor undersaturations from (p/p ) =0.80 to 0.006, either in a residual vacuum of about 1 x 10" torr. or in an oxygen environment up to pressures of

3 x 10"^ torr.

Under these conditions, evaporation pits were produced at either pre-existing steps or flat-surface regions. A critical undersaturation ratio of 0. 29 was required to produce

these features, which persisted to the lowest undersaturation employed. The number density of the evaporation pits did not vary with undersaturation in this range, being about

4 X 10^ cm" . The average dislocation density in the same samples, determined by chemical

etching methods was 3 x 10 cm" . This fact, combined with observations on evaporated

matched cleavage surfaces, lead to the conclusion that dislocations were particularly

effective in nucleating the evaporation pits. Interferometric pit-slope measurements

showed the slopes increased with increasing undersaturation and with increasing surfaceimpurity concentration. There was no apparent effect on varying the bulk-sample purity

between 99. 9?o and 99.998%.

The results are in agreement with some aspects of the theory of surface evaporation

from dislocation sites, but indicate the need for a quantitative treatment of dislocationcore effects and impurity effects. High resolution electron-microscope surface studies

indicated very complex step configurations, both near and away from the step sources

(See Fig. 6. ).

13
Figure 6. Electron micrograph of a shadowed carbon

replica from a thermally evaporated {0001} zinc surface,

illustrating the step structure at evaporation pits.

Magnification = 4400.

14
3. Defect Characterization

Contributions to this section are concerned

with studies of defect- or dislocationsensitive properties of single crystals

3. 1. Studies of Crystal Defects

D. J. Barber and N. J. Tighe,

Physical Properties Section

As part of a study of the mechanical behavior and defect properties of oxide materials

(Barber, 1963; Barber and Tighe, 1963), specimens thinned from bulk samples of sjmthetic

sapphire, ruby, and "star" sapphire, have been examined by transmission electron microscopy.

Glide elements for the Q;-Al203 system have been confirmed but, in addition, dislocation

loops have been found which lie in the {OOOlJ plane and have their Burgers vector in the

c-direction. There is some evidence for the occurrence of precipitates in ruby; Ti02

precipitates in"star" sapphire have been examined but no associated dislocation configurations have been seen. Further work will be carried out using a hot stage in the microscope.

In further work on materials with the rutile structure, magnesium fluoride, MgF2,

crystals have been thinned by ultrasonic drilling and subsequent polishing in hot sulfuric

acid.

In the electron microscope the crystals suffer beam damage; many small dislocation

loops appear, and these grow and interact. The loops will be studied in detail to determine their character. Cobalt fluoride, C0F2, which also possesses the rutile structure,

does not exhibit damage at comparable beam intensities.

3.2. Defects in Thin Oxide Films

J. Kruger, H. T. Yolken, and J. P. Calvert,

Metal Reactions Section

These studies are concerned with the role of defects in thin oxide films in the

kinetics of growth and decay. They consist of:

a) A study of the role of crystal orientation .and of dislocations on the sites of

passive film breakdown. (J. Kruger, 1963).

b) Optical studies of strain in thin oxide films formed on iron and copper singlecrystal surfaces, and electron-diffraction studies of the epitaxial relationships

between film and substrate.

3. 3. Surface Structure of Vapor-Grown Crystals

R. L. Parker, Metal Physics Section

For background see the description in NBS Technical Note 174 Section 5. 23.

Professor A. R. Verma, Varanasi, India, has examined some cadmium platelets grown at NBS from the vapor. Because of their small size (~0. 2 mm diameter) and rather firm attachment to the curved walls of the growth vessel, it proved to be difficult to mount the

crystals properly for multiple-beam interferometry. Larger platelets will be grown and

sent to India.

15
3.4. Surface Behavior of Copper Single Crystals

in Fused Sodium Chloride

J. Kruger, Metal Reactions Section and

K. H. Stern, Electrochemistry Section

This work is an extension of the study described under Section 5. 24 of NBS Technical

Note 174. The same approach and techniques are being applied to the study of copper. This

work which is in its preliminary stages has thus far revealed that the crystallographic

orientation of the copper substrate has no influence on the rate of etching at 900°C in the

presence of air.

3.5. The Effect of Point Defects on the Dynamic

Properties of Crystals

J. B. Wachtman, Jr. and Sam Spinner,

Physical Properties Section

Elastic and electrical properties are being studied as a function of temperature and

frequency, and the results interpreted in terms of chemical impurities and related point

defects. A program of measurements on doped magnesium oxide, MgO, and doped rutile, Ti02,

is in progress. A new internal-friction peak has been discovered in nickel-doped rutile.

This peak is being studied to see if illumination of the crystal during measurement reduces

the peak as might be expected from results on the effect of light on the electron-spinresonance spectrum. The present two-terminal electrical measurements will be supplemented

by four-terminal measurements as soon as a new four-terminal holder is completed. Previous

work on the relaxation process associated with CaO in Th02 is in press (Wachtman, 1963).

The elastic constants for rutile (Wachtman, Tefft, and Lam, 1962) and for strontium titinate

(Wachtman, Wheat, and Marzullo, 1963) were published. The latter paper describes a mathematical analysis which permits cubic crystals of arbitrary orientation to be used in

elastic-constant determinations.

Theoretical work in collaboration with H. S. Peiser (Crystal Chemistry Section) has

been continued. This work concerns the lowering of crystal symmetry by an applied stress

or electric field and the classification of the point-defect relaxation processes permitted

by the remaining symmetry. A survey of the effect of homogeneous stress on the sjmunetry

of the common-oxide structures and a discussion of the internal friction permitted by

symmetry is in press (Wachtman, Peiser, and Levine, 1963).

3.6. Precision Measurement of the Fundamental Electrical

Properties of Semiconductor Crystals

J. C. French, L. J. Swartzendruber,

G. G. Harman, and H. A. Schafft,

Electron Devices Section

Experimental equipment has been set up for the preparation of accurately dimensioned

semiconductor samples and for the resistivity measurements which will be made using a specially constructed traveling probe in conjunction with a potentiometric technique for

the comparison of the resistance of the semiconductor with a standard resistor. A chopped

current is used to minimize the effects of thermally induced voltages. In the first

homogeneity measurements, rectangular parallelopiped samples will be used, with the probe

system measuring the potential developed by a current flowing through the bar as a function

of position of the probe with respect to a reference electrode at one end of the bar.

In preparation for these measurements, some studies are underway of the limitations

imposed by the characteristics of the probing needle, the semiconductor surface, and their

interaction. Specifically, measurements have been made of the relations of the needle tip

radius, the force of application, and the surface finish of the sample to rectification

16
Figure 7. Wear of a 40|a

radius tungsten carbide

needle on a silicon surface lapped with 5^ abrasive, (a) and (c) show

the needle before and

after 75 applications with

a force of 100 grams. On

(b) and (d) interference

fringes are superimposed to yield a quantitative measure

of the needle surface.

SCALE

Figure 8. Typical spreading resistance vs. needle force curves as obtained with a 40|_l radius tungsten

carbide needle on 10 ohm-cm p-type

silicon. For curve 1 the silicon

was highly polished, for curve 2 the surface was lapped with a 5\i abrasive, and for curve 3 the surface was lapped with ll|j, abrasive.

The dotted line is a theoretical

curve for perfect needle contact.

Curves 1, 2 and 3 are mean curves,

as some variation occurs, especially

at the lower forces.

FORCE ON NEEDLE , grams

17
effects at the contact and to such factors as needle wear, the accuracy of sample-dimension

measurement and probe location, as well as the electrical sensitivity and linear resolution

of the probe system. The electrical sensitivity of the system is limited in part by the

spreading resistance of the needle-semiconductor contact, and the sensitivity, in turn,

provides one limit to the minimum detectable difference in voltage and hence to the linear

resolution as the probe is advanced along the sample.

Figures 7 and 8 illustrate some of these effects for tungsten carbide tips applied to silicon surfaces. Along with other considerations, such data lead to the conclusion that

in the resistivity range of interest (initially about 0. 1 to 10 ohm-cm), practical limits

of potential and linear resolution of a few microvolts and a few microns respectively are presently imposed by surface conditions.

In Section 5. 14 of NBS Technical Note 174, a reference was made to the study of

second breakdown in transistors (project leader, H. A. Schafft). This is a widely observed

but unexplained phenomenon which limits transistor capabilities. There is reason to believe

that crystal defects influence the initiation of this breakdown. Some evidence in support

of this hypothesis was found in our measurements which showed that the distribution of

failure sites due to second breakdown was not compatible with the way in which the theoretical current density depends on base drive. Examination of the region around these

failure sites has failed to disclose the existence of defects in the crystal or in the

device fabrication to account for this inconsistency. However the defect may have disappeared as a result of the local melting of the crystal at the failure site. The use of

temperature-dependent phosphors has begun in order to locate the region in the transistor

where second breakdown occurs. This will make possible the study of the crystal at these

regions before catastrophic failure.

* The electroluminescence and contact studies (project leader G. G. Harman) have con- tinued with investigations of the surface barrier on silicon carbide following the methods

of papers cited in the previous report (NBS Technical Note 174 Section 5. 14). Work on the

observation and application of charge stored in the surface states on silicon has been

completed with the publication during this period of the pertinent results (Harman,

Raybold, and Meyer, 1963 and Swartzendruber, 1963).

Further results on the studies of muscovite mica, which have now been completed, were

recently published (Ruthberg, Barnes, and Noyce, 1963a and b).

A new project (under J. C. French) has been established for the purpose of making

available solid-state device technology as far as it may help the experimental capabilities at NBS. Facilities for crystal orientation, sawing, lapping, polishing, alloying,

diffusion, and lead attachment are in preparation.

3. 7. Soft X-Ray Spectroscopy of the Solid State

R. D. Deslattes,

Crystal Chemistry Section

This project is planned to include both studies of long wavelength X-ray spectra and

crystal characterization by means such as diffraction topography. Activities during the

period of this report were confined to component production and assembly of the apparatus

required for the above studies.

The planned spectroscopic studies require a vacuum two-crystal spectrometer and

associated electronic instrumentation. The spectrometer still lacks a completed X-ray tube

and detector. The setting circles are not yet available. However, the spectrometer itself has been assembled and evacuated without difficulty. Sufficient electronic equipment

has been obtained to permit manual operation.

*This work was supported in part by the Air Force Cambridge Research Center.

This work has been supported in part by the Government Services Administration.

18
All the major components for a Ross-mounting two-crystal instrument of considerable

mechanical stability and angular sensitivity have been completed. Its full stability will

be realized after the assembly has been mounted to a diabase block. Preliminary tests

show an axial stability of better than one second for the second crystal mount and a maximum error of one second for the first crystal slide. The tangent drive is read by a tenpart vernier to 0. 1 second. The electronics required for manual operation of this instrument have been obtained. During the next six months it is planned that both systems will

be in routine operation. The provisions for automatic data recording will then be implemented and absolute-angle measuring facilities installed.

3.8. Spectroscopy Applied to Crystal Growth

G. L. Pollack, Crystal Growth Section

The effect of impurities on crystal growth is being studied by examination of absorption spectra of typical diatomic "impurities" in solid solution with rare gases. From

these experiments such processes as zone refining of crystals and transport in crystals

may be studied (Pollack, 1964). In addition, results of interest for molecular spectroscopy have been found from these studies (Pollack and Broida, 1963b).

3.9. Improved Sources for Spectrographic Analysis

B. F. Scribner, M. Margoshes, and S. D. Rasberry,

Spectrochemistry Section

a. Gas-stabilized arc: The gas-stabilized arc (Margoshes and Scribner, 1963) was developed to improve the precision of spectrographic analyses. A study of the detection

sensitivity of this source for several elements in dilute aqueous solution and in various

matrices is presently in progress. In addition, inter-element effects on emission intensities as well as the precision of analysis for major and minor constituents using this source will be studied.

b. Gas -sheathed arc: A device has been designed and built which provides a con- trolled atmosphere of any desired composition while retaining the speed of analysis that

characterizes emission spectroscopy. By enclosing the electrodes and the discharge in

a concentric tube of flowing gas, many of the practical difficulties of previous designs

have been eliminated. A systematic study is now in progress on the effect of controlled

atmospheres on the vaporization and excitation in arc discharges, particularly in terms

of the effect on the sensitivity of detection of the impurities in highly purified materials.

3. 10. A Laser Microprobe for Analysis of

Very Small Samples

B. F. Scribner, M. Margoshes, and S. D. Rasberry,

Spectrochemistry Section

The laser microprobe mentioned in NBS Technical Note 174 Section 5.9 was delivered by

the manufacturer in May. Figure 9 shows an over-all view of the device. Since this represents the first such instrument delivered by the manufacturer, considerable investigation

will be needed before the device can be applied to routine analyses. Studies are in progress to determine the best operating conditions for the instrument, to optimize the

illumination of the spectrograph and to establish methods for quantitative analysis.

The instrument uses a ruby laser which produces a pulse having a duration of 10

second and a peak power of 10" watts. A metallurgical microscope is used to select the

portion of the sample to be analyzed and to focus the laser beam on this spot. The pulse

will vaporize any solid material and at optimum focus it will form a crater 50 microns in

diameter and 25 microns deep (total volume ~ 3 x 10"8). The spot can be made wider and

shallower by defocusing the laser beam. The microprobe should allow the analysis of very

small samples such as portions of a specific crystal face or of segregates or inclusions

in samples.

19
Figure 9. The Laser Microprobe. Figure 10. View of the sample and electrodes at the moment of vaporization and

excitation. The eyepiece of the metallurgical microscope is just above the

electrodes.

>-

CO

LlI Q

0.5

0.4

< 0.3

o

^0.2

0.1

1 I I 1 I r SPINEL (:Co)(^A2)

^T, (F)

I I I I 10

Figure 11. Spectrum

for Mg-Al spinel with

small concentration of

Co.

15

cm"' X 10"^

20

20
The spectra of the elements in the vaporized saigple are dKcited by a variable spark

discharge between two graphite electrodes and are analyzed spectrographically. Figure 10

shows the sample and electrodes at the moment of vaporization and excitation.

3. 11. Optical-Property Studies

R. W. Dickson,

Physical Properties Section

A low-temperature holder for a ruby laser crystal is being constructed. It is intended to control the frequency of the laser beam by controlling the temperature of the laser

crystal. The resulting beam will be used in the study of clustering of chromium ions in

ruby.

3. 12. Optical Properties of "Pure" and Impure Crystals

L. H. Grabner and R. F. Blunt,

Solid State Physics Section

*

a) Semiconductors

The optical equipment is now in the stage that measurements of photoconductivity can

be made under simultaneous excitation by two sources. Good quality CdTe samples (see

Section 2. 2) are presently being investigated.

b) Defect Studies

Spectra of cobalt-doped spinel have been recorded at room temperature, 78°K, and 4°K

(see Fig. 11). There is strong indication that the Co"^ ion is situated in a tetrahedral

site. The major bands at ~ 7, 200 cm"-'- and ~ 17, 000 cm"-'- are identified as the ^A2 (F) >

^Tl (F) and the ^A2(F) > ^T]^(P) transitions, respectively. The D value is ~ 400 cm"!. Yet to be explained are the structure of these bands and the absence of the ^A2(F) > ^12 (F) transitions (expected at about 3,500 cm"-*-). It is possible that the latter is

masked by the presence of an OH-band (which has been observed both in clear and in Co-doped

spinel).

3. 13. Automation of Single-Crystal X-Ray

Diffraction Intensity Measurements

F. A. Mauer,

Crystallography Section

In the past. X-ray diffraction patterns used in the determination of crystal structure were almost always recorded on photographic film. Considerably more accurate data can be

obtained by direct measurement of the dif fracted-beam intensity using a proportional or scintillation counter. With the enhanced speed and precision of measurement the intensity

data may be useful as a measure of crystal perfection as well as in structure analysis.

Direct measurement of intensities requires orientation of the crystal with respect to

three axes, and the counter with respect to a fourth for each of a thousand or more reflections. For each reflection a fairly elaborate procedure is followed in measuring the

integrated intensity. When carried out by hand, the method is slow, requiring the constant

attention of a skilled operator for periods of six weeks or more.

Several laboratories, particularly in England, have adopted automatic equipment for

setting the crystal and recording the integrated intensities. At the National Bureau of

Standards a study of existing automatic single-crystal dif fractometers has been completed

*This work was supported by the Office of Naval Research.

21
Figure 12. Laue diagram of a/^3-mm thick

ammonium dihydrogen phosphate crystal

section perpendicular to the fourfold axis

Figure 13. Laue diagram of potassium cry- stal showing much orientation spread.

Figure 14. Enlarged Laue diagram of 2-cm

thick aluminum crystal grown by Bridgman

technique.

Figure 15. Two half Laue diagrams of

ammonium dihydrogen phosphate crystals grown

respectively top with and bottom without

addition of Cr3+ ions. Corresponding Laue

spots are diagonally opposite each other.

22
and specifications for an improved instrument have been drawn up. At least two manufacturers are prepared to build such an instrument, and it is expected that one will be ordered

in the fall of 1963. In the meantime, measurements are being carried out by hand to determine the exact procedures the- machine will be programmed to execute.

3. 14. High-Voltage Laue Photographic

Inspection of Large Single Crystals

B. Paretzkin and H. S. Peiser,

Crystal Chemistry Section

The high-voltage method has been further developed (compare NBS Technical Note 174

Section 5.13). X-ray diffraction photographs have been taken of single crystals through

walls of vessels and furnaces composed of polycrystalline materials.

Figure 12 shows a Laue diffraction picture of a good ammonium dihydrogen phosphate

crystal. Figure 13 illustrates a bad potassium crystal. Figure 14 shows enlarged diffraction spots of an aluminum crystal grown by a Bridgman technique. The topographic detail

demonstrates the presence of polygonization absent from strain-annealed crystals.

Primary extinction is a feature of Laue photographs of good solution-grown crystals of

ammonium dihydrogen phosphate. The addition of impurity chromium ions to the growth bath

reduces the attenuation of strong diffraction spots due to primary extinction (Figure 15).

3. 15. Dilatometric Studies of Polymers

J. Powers and F. A. Quinn,

Macromolecules Synthesis and Structure Section

The polymorphism previously reported in polybutene-1 and polypentene-1 (NBS Technical

Note 174 Section 5. 21) is being investigated by wide-angle X-ray diffraction.

In addition, dilatometry is being used to delineate the maximum in the isothermal

crystallization rate in polystyrene. Morphological and growth-rate studies using photomicrographic techniques are being carried out concurrently. Preliminary specific-volume/

temperature measurements show a change in slope at about 95°C indicating that the

isotactic polymer has a glass transition temperature in the same range(80°-100°C) as the

atactic.

4. Crystal Physical Properties

Contributions to this section are concerned with the

physical properties of crystals which do not depend

primarily upon the degree of crystal perfection or whose dependence on that perfection is not the principal aim of the investigation. *

4. 1. Velocity of Sound in Ice Single Crystals

T. M. Proctor, Sound Section

Thermal expansion and specific heat data [Butkovick, J. Appl. Phys. 30. 350 (1959)

and Flubacker, Leadbetter, and Morrison, J. Chem. Phys. 33. 1751 (I960)] have indicated that

single crystals of regular ice show an unusual phonon spectrum at low temperature. Elastic

constants for ice found in the range of 0°C to -30°C indicate a large discrepancy between

Cy as measured at low temperatures (20°K) and C^ as calculated from these constants. An

attempt to correlate velocity of sound data with specific-heat data at low temperatures

has been undertaken in a project started about 1-1/2 years ago. The primary aim of this

project is to measure the velocity of sound in single crystals of ice down to liquid-helium

}y.This work is carried out with partial support from the Office of Naval Research.

23
temperatures.

Techniques for measuring velocity of sound in solids down to liquid -helium temperatures

have been investigated. A method which measures the velocity with a high precision has been

devised and the apparatus is almost complete (a low temperature cryostat has been in use for

almost a year; velocity measurements have been made down to 55°K a number of times). Techniques for growing large single crystals of ice have been refined. (Samples of 1-1/2 inches

in diameter and 2 inches long have been grown. ) Crude early measurements down to liquidnitrogen temperatures indicate that ice has a positive slope in its velocity temperature

curve. These data do not show the presence of the expected low-temperature vibrational

mode. It may well be that liquid-nitrogen temperatures are just not low enough to detect

this mode but it may be detected when the experiment is performed at liquid-helium temperatures. *

4. 2. Electronic Transport

H. P. R. Frederikse and J. H. Becker,

Solid State Physics Section

Measurements of conductivity cr, Hall effect Rjj and thermoelectric power CC are aimed at

a better understanding of the electronic transport and the defect structure of oxides [in

particular Ti02 and SrTi03, (also Fe203 and Cu20) compare Becker and Hosier (1963) and

Yahia (1963)]

Detennination of crand R^ at helium temperature show a temperature dependence which indicates conduction in impurity levels (or bands). Excitations to higher bands are studied

by measuring the conductivity and Hall coefficient under illumination. The increase of R^

is strongly dependent on the light intensity. Presently the wavelength dependence of these

photo effects is being examined.

Investigations of the anisotropy of the Hall effect and the Seebeck coefficient over

the entire temperature range seem to confirm the existence of a "second" conduction band

within 0.05 - 0.10 ev of the bottom of the "first" conduction band.

Measurements of the Seebeck coefficient OC of TiO„ and of SrTiO down to 15°K have shown

that the phonon-drag effect accounts for most of the magnitude of the coefficient of rutile

at low temperatures, while it seems to be absent in SrTiO-.

4. 3. Hall-Effect Measurements

S. Rubin, Engineering Electronics Section

The objectives of this project are the establishment of standardized terminology and

measuring methods for Hall-effect generators and related devices.

A proposed Standard for Hall-generator definitions, terminology, letter and graphic

symbols is in process of preparation. There is included a definition of linearity error as

a percentage of reading, in addition to the usual linearity error as a percentage of full

scale. Descriptions of measuring methods are included as an appendix to the definitions.

The proposed Standard has been submitted to the American National Committee of the

International Electrotechnical Commission, TC 47, which, through its affiliation with the

International Organization for Standardization, acts in a consultative capacity to UNESCO,

Additional work in the development of instrumentation for the precise measurement of

small magnetic fields in restricted areas using electron-paramagnetic resonance is

proceeding.

This work was supported in part by the Office of Naval Research

This work was supported by the Bureau of Naval Weapons.

24
4.4. Dielectric Constant and Losses

J. H. Wasilik,

Solid State Physics Section

The dielectric constant 6 ' of monocrystalline lead fluoride^ Pt)F_, has been measured

at room temperature and at frequencies from 10^ to 10' cps. At 300°K the value of €' appears

to be 28.7 ±.4; preliminary results indicate a small increase at helium temperatures. The

refractive index of PbF„ has been measured; this additional information permits the determination and analysis or the polarizabilities of the two ions.

Attempts to observe the loss due to excitons are continued; the substance under investigation is now CdS rather than Cu„0. The lifetime of excitons in the former is considerably

longer than in the latter, producing larger exciton concentration in CdS.

4. 5. Electron-Lattice Interaction

R. P. Hudson, Heat Division

In both low-frequency and high-frequency phases of the work, efforts of three parttime staff members have been concentrated on instrumentation.

a) Audiofrequency Measurements

The new mutual-inductance bridge, one of three constructed recently in the Cryogenic Physics Section, was set up. A simplified selective amplifier was constructed to replace the one taken over from the magnetic -coo ling apparatus. An electronic thermostat

for the helium bath was constructed in collaboration with the Instrumentation Division,

b) Pulsed Microwave Measurements

A plastic X-band microwave cavity was manufactured but to date has not been

silvered satisfactorily; even so, a Q of 4000 was achieved so that the prospects are good

for the eventual production of a very good cavity. Also designed and constructed were a separate filament -power supply to reduce the klystron-noise level; a small d. c. supply for

applying bias to the diodes in the microwave switch; a simple solid-state phase-sensitive

detector for conventional presentation of e.p.r. signals during check-out procedures.

A superheterodyne unit (radar receiver) was borrowed from the Instrumentation Division

and put into operating condition; it is not, however, an ideal unit for the present application and is currently being replaced by a radar receiver obtained commercially; a power

supply for it is under construction. [The need for high-sensitivity and wide-band detection

seems to dictate use of the superheterodyne method although the video-detection method may

prove adequate in some instances.

]

The vertical-axis -rotation bearing originally supplied with the new electromagnet was unsatisfactory; it has just been replaced with a heavy-duty bearing, which works well.

4.6. Studies in Solid-State Theory

A. H. Kahn, Solid State Physics Section

a) The tight -binding calculation of the electronic energy bands of rutile, TiO , has progressed to the stage where the only remaining work is the computer programming. This is

in progress. Results will be compared with experimental data on galvanomagnetic and

optical properties of rutile crystals.

b) Calculations similar to those on TiO. are now being performed for BaTiO and SrTiO_ in an attempt to understand similarities and differences in the electrical and optical behavior

of these related compounds (see Section 4.2). ^ __——^—

This work was supported by the Atomic Energy Commission.

25
c) A study of transport effects in tetragonal semiconductors has been carried out by

W. C. Hernandez, Jr. and A. H. Kahn (1963). The effect of energy-band anisotropy on the

galvanomagnetic and thermoelectric coefficients has been determined for simple ellipsoidal

models.

4.7. Isotopic Impurities and Energy Transport in

Harmonic Crystals

R. J. Rubin,

Temperature Physics Section

Energy transport in harmonic crystals containing isotopic defects is being investigated. A general theoretical model has been studied in which a harmonic crystal is divided

initially into two regions characterized by different temperatures. Cooling curves have

been calculated for several one -dimensional crystals: 1) an infinite perfect crystal;

2) an infinite crystal containing one isotopic defect; and 3) several 100- and 200-

particle isotopically disordered crystals consisting of equal numbers of two isotopes.

An account of this work will appear in the August 1 issue of the Physical Review. (See

also Rubin, 1963).

At present the phonon-transmission characteristics of a slab of isotopically disordered crystal inserted in a perfect crystal are being studied.

4.8. Cryomagnetic Theory

J. C. Eisenstein,

Cryogenics Section

During the past year work was concentrated on magnetic and optical properties of rare- earth trichlorides. These compounds are interesting because of the possibility that they

may become ferromagnetic at very low temperatures. Detailed analyses were made of the

optical spectra of Nd and Er-* in solid LaCl~ and two papers were written on these ions. In a third paper the spectra of Nd in LaCl^ and Nd in LaBro were analyzed and compared

and it was shown how the host lattice affects the energy levels. A fourth short paper

dealt with the magnetic properties of the ground state of Ce in LaClo. Finally, the

angular parts of the wave functions for three equivalent f electrons which are eigenfunctions of L^ , S^, J^ and J^ were tabulated.

4.9. Energy Transfer Below 1°K

J. F. Schooley and E. R. Pfeiffer,

Cryogenics Section

This project has the responsibility for the preparation of single crystals used in

research in several of the projects in the Cryogenic Physics Section in addition to the

measurement of energy transfer at low temperatures.

Hydrated crystals, principally ethylsulfates and double nitrates of the rare earths

are grown by the techniques of isothermal evaporation of solutions, of temperature re- duction of saturated solutions, and of thermal gradient pumping within solutions.

Experiments on the thermal conductivity of single crystals of the above type at approximately . 02-. 10°K by means of the steady-state temperature gradient technique are

in progress. The secondary thermometers employed in this technique are the paramagnetic

susceptibility of the crystal and the anisotropy of gamma radiation from oriented radionuclei.

Two papers describing preliminary work have recently been published (Schooley, Hoppes,

and Hirschfeld, 1962, and Schooley and Hoppes, 1962).

26
4, 10. Low-Temperature Nuclear Orientation

E. Ambler, H. Marshak, R. S. Kaeser, and R. B. Dove,

Cryogenics Section

Helium-3 refrigeration has been used to produce a substantial degree of nuclear alignment in single crystals of holmium ethylsulfate, and bremsstrahlung from the NBS betatron

has been used to study the (x, n) cross-section as a function of angle between the beam

and the crystalline alignment axis. The anisotropy found demonstrates the tensor nature

of the nuclear polarizability of holmium.

4. 11. Low-Temperature Thermometry

H. Plumb, G. Cataland, and M. Edlow,

Cryogenics Section

A portion of the NBS effort in low-temperature thermometry is concerned with the

resistance of impurity-doped germanium crystals as a sensitive function of temperature

below 20°K. In similar work with carbon resistors, the resistance was found to obey the

following semi -empirical equation between 2° and 20°K:

log R + K/log R = A + B/K

Here, A, B, and K are treated as constants to be determined experimentally.

4. 12. Nuclear-Resonance Thermometry

S. F. J. Read,

Temperature Physics Section

The purpose of the project is to measure the temperature dependence of pure quadrupole

and nuclear-resonance frequencies; and to investigate the applicability to precision

thermometry.

35 The quadrupole-resonance frequency of CI in KC10„ is one possible thermometer.

The frequency is believed to depend on both impurities and crystal imperfections. KCIO.

crystals are being grown and the reproducibility of the thermometer is being investigated.

4. 13. Metal-Oxide Melting-Point Standards

S. J. Schneider,

Crystallography Section

The program, which was initiated in mid 1962, consists of three distinct areas:

(1) compilation of melting-point data through a critical review of world literature;

(2) experimental determination of the melting points of many oxides under various environmental conditions and the selection of several oxides deemed suitable for use as standards;

(3) refinement of the melting points of the selected oxides.

During the past months, phase (1) has been completed and will be published (Schneider,

1963). The compilation indicated that no single metal oxide has been studied in sufficient

detail to justify its use as a melting-point standard. Equipment for phase (2) has been

assembled and is currently being tested.

27
4. 14. Reduction of Space Groups to Subgroups

by Homogeneous Strain

H. S. Peiser, Crystal Chemistry Section; and

J. B. Wachtman, Jr. , and R. W. Dickson,

Physical Properties Section

Tables showing the lowering of space-group S3mimetry for all space groups and all types

of homogeneous strain has been accepted for publication (Peiser, Wachtman, and Dickson,

1963).

The symmetry of strained crystals is important in the following considerations:

(1) The presence or absence of internal friction resulting from the motion of point defects

in a crystal can depend upon whether or not the initially equivalent sites accessible to the defect are inequivalent in the strained crystal. (2) Any tensor property of a crystal,

such as piezoelectricity, depends primarily upon the symmetry of the unstrained crystal,

but additional tensor components may be introduced by straining the crystal in such a way

as to change its symmetry. (3) A classification of the types of polymorphism of crystals

has been proposed by M. J. Buerger; in some categories no bonds are broken but only a symmetry change takes place. Some structural changes can be induced by homogeneous strain.

(4) Solid solution of an impurity atom is usually accompanied by strain which may lower

the symmetry. (5) Large strain fields exist near dislocations and accompanying symmetry

changes may be associated with large local variations in physical properties such as enhanced diffusion near a dislocation. (6) Strain-induced alteration of symmetry may

cause change in electron-spin resonance or infrared absorption; measurements of these

changes may give information on the type of site occupied by a given point defect.

4. 15. Magnetic-Susceptibility Measurements

B. W. Mangum, Cryogenics Section

Various anhydrous paramagnetic crystals, principally rare-earth trihalides, have been

grown in a temperature gradient furnace.

A mutual-inductance coil, a mutual-inductance bridge, and the cryostat have been

completed, and measurements of paramagnetic susceptibilities in the range 1°K-300°K are contemplated.

A

4. 16. Magnetic -Resonance Studies I

T. Chang, R. A. Forman, and R. E. Pajme,

Solid State Physics Section

a) Electron-Spin Resonance

The study of Mo-doped rutile, TiO„, was brought to a successful conclusion. The

spectrum is shown in figure 16. The use of a cavity designed for circularly polarized

microwave radiation enabled the unambiguous determination of the sign of the g-factor.

An account of this work is being written (T. Chang, 1963).

Sm- other studies are concerned with the Ti - center in reduced TiO-. Preliminary measurements confirm the results of P. F. Chester [J. Appl. Phys. Suppl. to _32, 2233 (1961)].

b) Nuclear -Magnetic Resonance and Quadrupole Resonance

The study of the N-nucleus in azides is being continued. The quadrupole coupling

constants of each of the three N nuclei in (gaseous) HN^ were determined from the microwave

spectrum. The assignment was made possible by using three N-'--'-substituted species

^Supported in part by ERDL-Ft. Belvoir, Department of the Army.

28
o

a

d)3

(Uu

CM O

u

a

•r^ +in og

U-lo

6

3

V4 JJo

(Ua0]

(Uo

c

cdC

o

CO

Q)M

d

•1-1 O.w

co^ , u t^ o o

cu 00

r-) r~- w

*v 0)M

vO 3

t—

1

j-i

cfl 0) !-i

!-i OJ 3 d. M H

•H 0)

|ii 4-1

29
(Forman and Lide, 1963).

14

The chemical shifts of N in sodium azide solution have been measured. The determination was made relative to a saturated solution of sodium nitrate. No effect of solution

concentration was noted on the chemical shifts (Forman, 1963).

Investigations of nuclear resonances in the internal field of ant i ferromagnetic

materials are being planned. Oscillators are tested in the 30-80 Mc range.

4. 17. Magnetic-Resonance Studies II

L. M. Matarrese, J. S. Wells, and A. R. Cook,

Radio and Microwave Materials Section

In connection with the EPR investigation of amethyst the EPR spectrum of iron-doped

synthetic quartz is being studied at X-band and K-band. This spectrum has the same general

features as that of amethyst, but differs greatly in detail. The color of the specimens

varies from pure green through green-yellow to yellow, the green being obtained under

oxidizing conditions. The color makes little difference in the EPR spectra however,

which, at room temperature, all resemble that of ferric ion. The spectrum consists of

three sets of lines, presumably from three inequivalent substitutional sites. Each set consists of five or more fairly intense, narrow lines and many weaker ones, spread over an extremely wide field range (0-900 G at X-band). The intensities of some of the lines vary

markedly with angle. There is a broad intense resonance at g = 2 at X-band but not at K-band.

Crystal-field theory has been applied to the interpretation of the spectrum with

rather poor results. The spin-Hamiltonian parameter D is of the order of 1000 G. We are now concentrating on the K-band spectrum in the hope of obtaining a better theoretical

interpretation.

A new method of preparing X-band and K-band cylindrical cavities for EPR work has been

developed. The method is described in a paper to be submitted to Review of Scientific

Instruments. The cavities are molded from epoxy resin and have a thin silver wall with

a spiral groove running from top to bottom. Besides suppressing unwanted modes, the

spiral groove permits excellent penetration of 100 kc magnetic field modulation.

A marginal oscillator operating in the 30-60 Mc range has been built for use in the

ENDOR experiments which are planned.

Millimeter -wave components are being acquired for the planned investigation of antiferromagnetic resonance.

4. 18. Microwave Measurements on Single-Crystal Ferrimagnetics

A. S. Risley,

Radio and Microwave Materials Section

Measurements have been made of the ferrimagnetic resonance of single crystals of

manganese ferrite and nickel-zinc ferrite. The data were obtained on rods and spheres of

these materials at a frequency of 9. 15 Gc. The results of the linewidth, H, measurements

were: Ni-Zn; H^od ~ ^sphere~^°° oersteds. Mn;AHrod~22 oersteds with Hgphere ranging

from 26 to 40 oersteds as a function of its orientation with respect to the D.C. field.

The sphere measurements were perfoinned on a sample whose average surface roughness was

63 microns. The same sphere, polished to 0.2 microns, varied between 20 and 25 oersteds

with orientation. These tests were made without reference to X-ray orientation studies.

The stock from which the samples were fabricated was supplied to the National Bureau of

Standards in May of 1953. Further work is planned using X-ray orientation observations,

provided other suitable crystals are obtained.

30
4. 19. Work Functions of Perfect Single-Crystal Planes of Tungsten

R. D. Young, Electron Physics Section

Recent developments in field-ion microscopy have enabled the creation and observation

of atomically perfect single-crystal planes of refractory materials. Field electron

emission from tungsten single-crystal planes is being employed to measure the work function

of these well characterized surfaces. The present experiments also include provision for

simultaneous measurement of the energy distribution of photoelectric emission and field

electron emission from the same plane, permitting an absolute measurement of the work

function of these perfect planes. Since all low-index planes are simultaneously available,

it will be possible to study the dependence of work function on the detailed atomic arrangement of a particular crystal lographic plane.

4. 20. Interaction of Low-Energy Particles with Surface Atoms

R. D. Young and R. S. Will, Electron Physics Section

A technique has been developed for studying interactions in the few milli-electronvolt range between uncharged particles and surface atoms. In this work the field-ion

microscope is employed in the desorption phase to carry out such interactions, and in the

best image phase to determine which atoms have interacted. In this way the effect of

crystal plane (number of nearest neighbors, etc.) on the interaction process can be

studied. Future work will include the interaction of ultraviolet light with a tungsten or platinum single-crystal surface.

4. 21. Molecular Energy Levels

A. M. Bass, Heat Division

A study of the ultraviolet absorption spectrum of 0^ in liquid and in solid argon and

nitrogen has been made. As contrasted with the spectrum of gaseous 0„, the Schumann-Rung

e

bands (1750 to 2000 A) show a slight shading to the violet and a displacement to frequencies which are lower by 50 to 400 cm" . Little difference was noted between liquid and

solid or between nitrogen and argon media.

4. 22. Crystal-Field Studies by Matrix Spectroscopy

D. E. Mann, Molecular Spectroscopy Section

The investigation of environmental influences on the rotation-vibration spectra of

simple molecules isolated in solid rare-gas lattices has advanced along several new lines

as a result of recent observations. Earlier studies of the hydrogen and deuterium halides

showed the presence of both rotating and non-rotating species in various matrices. It was

found that the absorption bands of the non-rotating molecules were remarkably narrow. An

attempt is being made to determine precisely the actual limiting line widths, and to derive

from these data an indication of the degree of coupling of the molecular motion to the

lattice. In other recent studies it has been found that under certain conditions structure

which appears to be characteristic of vibration-rotation band envelopes is retained in

lattices even at 4°K. Several newly discovered examples are being studied to ascertain to what extent the observed envelopes reflect lattice influences on the rotational motions of

the molecules. New data have recently been obtained in support of the view that water

molecules trapped in solid rare-gas lattices execute nearly free rotation. Moreover, it

has been found that ortho-para spin conversion is strongly induced by the presence of trace

quantities of molecular oxygen in the lattice.

31
5. Crystal Chemistry

Contributions to this section are concerned with

studies of individual crystal phases involving

crystal structure, transformations, or chemical

properties not sensitively dependent upon crystal

perfection.

5. 1. Phase Equilibria

R. S. Roth and E. M. Levin,

Crystallography Section

Research is being conducted on glass-forming systems containing Si02, B2O3 or Ge02;

on systems of interest in electronic research such as those containing Nb205, Ta„Oc, ZrO„ or V2O5 ; and on very refractory oxides, such as the rare-earth oxides.

A paper elucidating the complex, stable and metastable, polymorphic relations of Bi203

has just been prepared for publication. This paper should enable scientists in research

and industrial laboratories to obtain a better understanding of this oxide widely used as an additive in the glass and electronic industries. Another contribution has been the

discovery that the solid solution widely reported to occur with additions of small cations

to Nb205 actually represents discrete phases with definite Nb -to-cation ratios. The

complete elucidation of the composition and structure of these phases should prove of

value in the fields of electronic ceramics and metal-oxidation studies.

Present plans call for a study of the discrete phases of Nb205 systems and a complete

study of rare-earth oxide/boric oxide systems.

For related work see Roth, Waring, and Levin (1963) and Schneider and Waring (1963).

5.2. Crystal-Structure Analysis

S. Block, H. M. Ondik, and A. Perloff,

Crystallography Section

The program of crystal-structure analysis has several facets: (a) evaluation of

methods of structure analysis, (b) determination of structural principles of inorganic

compounds such as borates and phosphates and (c) compilation of single-crystal data. In the past few months papers have been submitted for publication which indicate the applicability and some limitations of various formulae for structure analysis, and present the

crystal structure of 1-ethyldecaborane (Perloff, 1963/4), LiK2P309.H20 (Eanes and Ondik,

1962), NaB(OH)^. 2H2O (Block and Perloff, 1963/4), NaP309 and Na3P309.H20. Arrangements are being made for publication of future volumes of the book "Crystal Data" by NBS. Work is

continuing in all the above fields.

5.3. Standard X-Ray Diffraction Powder Patterns*

H. E. Swanson, Crystallography Section

Patterns of pure and well characterized inorganic solids are being produced for com- parison standards used in identifying crystalline materials of unknown composition. These

patterns have been published in twelve volumes the most recent of which (Swanson et al.

,

1963) includes patterns for 37 substances, 26 of which were not previously included in the

file (XRPDF) issued by the Joint Committee for Chemical Analysis by X-Ray Diffraction.

The remaining eleven replace earlier and less accurate patterns taken from various sources.

In all, NBS has contributed approximately 600 patterns. The need for additional patterns

is expected to continue indefinitely.

^This work is partially supported by the Joint Committee for Chemical Analysis by X-Ray

Diffraction.

32
5.4. Rapid X-Ray Diffraction Photography

of Polycrystalline Materials

R. E. LaVilla, Crystal Chemistry Section

In order to study the atomic rearrangements during transient phenomena, techniques

for the rapid recording of X-ray powder diffraction patterns are being <ieveloped. These

techniques will take advantage of the geometry of a fine-focus X-ray tube by coupling it to a miniature X-ray focusing camera. The applicability of a commercially available electronic image intensifier will also be explored. The desired X-ray diffraction pattern

will be obtained by synchronizing the driving force causing the atomic rearrangements in

the specimen with the pulsing of the X-ray tube and the grating of the image intensifier.

We hope to decrease the X-ray exposure times to about a millisecond. Shorter X-ray ex- posures will depend mainly on increasing the X-ray tube currents. It may be possible to increase the X-ray tube current by an appreciable factor if one grossly overloads the tube

causing burnout of the filament and target.

5.5. Application of Borrmann Crystals to the Construction

of a High-Resolution Small-Angle X-Ray Camera

H. Brumberger, Crystal Chemistry Section

The wave-length focusing property [see, for instance, Beeman, W. W. , Kaesberg, P.,

Anderegg, J.W. and Webb, M. B. , Handbuch der Physik, 32^ 428 (1957)] of nearly perfect

(Borrmann) germanium crystals cut to reflect from the {220} planes in the Laue position is

used to obtain 1:1 image of the focal spot of a micro focus X-ray tube at a distance of

50 cm. from the crystal. Because of the perfection of the crystal, a very good image is

hoped for.

For a lOOja focal spot, a diffracting sample located just past the Borrmann crystal,

and a beamstop about 200\i wide, an angular resolution of 2 x 10" radians should then be

attainable in the low-angle pattern,

5.6. Lattice Parameters and Energies of

High-Pressure Polymorphs of Some Alkali Halides

G. J. Piermarini and C. E. Weir,

Crystallography Section

Lattice parameters of high-pressure forms of all the rubidium halides (Pieinnarini

and Weir, 1962a) and potassium halides in addition to cesium fluoride are being determined

using a high-pressure X-ray diffraction camera (Piermarini and Weir, 1962b). The alkali

halides being studied have the NaCl-type structure at one atmosphere and 25°C. From

present results it appears that the observed high-pressure form of all these salts has the

CsCl-type structure. The measured values of the lattice parameters are being used to compare the lattice energies of the two phases in equilibrium at the transition pressure.

Within experimental error it appears that the Born-Meyer theory adequately accounts for

the lattice energy of the high-pressure phase.

5.7. Infrared Spectroscopy of Crystalline Inorganic Borates

C. E. Weir, R. A, Schroeder, and E. R. Lippincott,

Crystallography Section

Following on previous similar studies (Schroeder, Weir, and Lippincott, 1962) a number

of inorganic borates have been prepared for infrared spectroscopic studies and initial

spectra are being obtained using the null technique at room temperature. Spectral studies

will be correlated with the results of other work on the X-ray crystal structure of the

borates (see Section 5.2). In particular, the question of the effect of coordination of

the boron on the spectra will be studied. Spectra of single crystals of the borates will

33
also be studied in an attempt to correlate these studies with earlier work on libration of

anions.

5.8. Optical Observations of Pressure-Induced Transitions in Polymers

J. Powers and F. A. Quinn,

Macromolecules Synthesis and Structure Section

Continuing the study of pressure -induced transitions in polymers (NBS Technical Note

174 Section 4.11), light-transmission measurements have been carried out. These show an abrupt change in transmission in the pressure range where thickness and morphology change

suddenly. The results are reported in a letter to be published (Van Valkenburg and

Powers, 1963).

5.9. High-Pressure Microscopy of Crystal Transformation and Growth

A. Van Valkenburg, Crystallography Section

High-pressure optical studies have been carried out on (1) the silver and cuprous

halides at pressures up to 125 kilobars (2) cadmium sulphide at pressures up to 80 kilobars

and (3) the high-pressure forms of ice (ice VI and VII) at pressures up to 60 kilobars.

These studies were made using a diamond high-pressure cell, monochromatic light and a polarizing microscope (compare NBS Technical Note 174 Section 4.10).

The silver halides included Agl, AgBr, and AgCl obtained from commercial sources. A new birefracting phase was observed in silver iodide at 2400 bars (Van Valkenburg, 1963).

Another phase, which occurs at pressures above 100 kilobars, was reported earlier by

Drickamer, who assumed that it was cubic. However, the present study indicates that it is birefringent in character. It was also noted that the polymorphic pressure phase having

the NaCl structure appeared to exhibit a dark reddish color at 450 mp. and 3,000 bars,

which suggests a fluorescence phenomena.

The cuprous halides consisting of Cul, CuBr, and CuCl all have the sphalerite or zincblende type structure at ambient pressures and temperatures. Since they are structurally

similar it was believed that their polymorphic forms would also show similarities. Three

transitions, occurring at 4,5, and 15 kilobars, were found in Cul, and three transitions were found in CuBr, two occurring at 47 kilobars and a third at 80 kilobars. Two transitions were observed, at 42 and 55 kilobars, in CuCl with a possible third in the pressure

range of 80 kilobars.

Using a gasketing technique developed for the diamond high pressure cell, water was

frozen at ambient temperatures. Ice VI was obtained at pressures above 10 kilobars and

ice VII above 25 kilobars. The optical characteristics of these phases were observed. It was possible to grow a single crystal of ice VI from its liquid environment covering the

cell's entire field of view of about 2 mm. Ice VII appears to be isotropic and ice VI is

birefringent with a hexagonal outline. There also appears to be a third metastable phase

that exists between water and ice VI.

5. 10. Purification of Polymorphic Inorganic Solids and

Preparation of Crystals of a Single Polymorphic Species

A. R, Glasgow, Jr., Pure Substances Section

The purpose of this research program is to extend purification by phase transports

and separations to temperatures up to 1000°C, and to develop non-reactive metal systems

for carrying out such processes with inorganic fluorides in the presence of hydrofluoric

acid as a solvent. Particular emphasis will be placed on establishing p, T, and solubility

conditions that are necessary to obtain individually the different crystalline forms of

polymorphic inorganic substances.

34
At present the entire program is directed towards the preparation of high-purity

crystals of beryllium fluoride, BeF2, in a single poljrmorphic form. In addition to the

preparation of crystals of BeF2 by phase transports and separations at ordinary pressures,

a process similar to the hydrothermal growth of quartz from fused silica will also be

applied to BeF2 with HP as the solvent instead of water and with ammonium fluoride, NH4F,

as the flux material instead of caustic soda, NaOH.

Progress to date has involved mainly assembly of equipment for performing experiments

safely in a hooded area with non-reactive metal systems under closed-system operation and

under controlled temperatures. The equipment when fully operable will have wide applicability beyond the specific system under study.

5. 11. Crystal Chemistry of Silver Iodide

G. Hurley, Crystallography Section

Work described in NBS Technical Note 174 Section 5. 25 has been continued. The zero- point motion, the kinetics of the f-p phase transformation and the epitaxial nucleation of

ice by single crystals of silver iodide have been studied.

The temperature attenuation of the powder X-ray diffraction peak-heights of cubic

silver iodide was measured at 20°, 78° and 120°K. From this, and the room temperature

exponent obtained from single crystal data, the zero-point Debye-Waller exponent was deduced as 0. 21A . This corresponds to a zero-point thermal vibration of 0. 05A (R. M. S. amplitude).

The transformation of the face-centered cubic to hexagonal phase has been found to obey first-order kinetics. The energy of activation is 10.4 ±1.3 kcal/mole. Within the

limits of error, this is equal to the activation energy for defects, given as 11. 2 kcal/mole

in the literature. The mechanism of this transformation is therefore probably related to the generation of lattice defects.

The observations of the nucleation of ice on hexagonal silver iodide have now been

extended to large single crystals. On freshly prepared crystals the ice growth is predominantly on the {100} and {lOlj surfaces. After irradiation with a mercury lamp the

predominant growth site is the {001} basal plane. This behavior is in excellent agreement

with the model for the photolytic breakdown of silver iodide previously proposed (Burley,

1963a) on the basis of the observed primary extinction in X-ray diffraction patterns.

The study of silver iodide is now being concluded with a radial distribution analysis

of the body-centered cubic structure at 160°C, which is just abdve its lowest stability

temperature, with the intention of clarifying the mechanism of the "memory" of phase

retention in a cyclical process.

The structure of hexagonal Agl has now been published (Burley, 1963b).

5. 12. Phase Equilibria in Dilute Polyethylene -Diluent Systems

F, Gomick, Macromolecules Synthesis and Structure Section

Although a great deal of work on the crystallization behavior of polyethylene from

dilute solution has been reported, very little is known about the thermodynamic parameters

of the crystallization process in various solvent systems. Work is now being carried out

to study the phase diagram of polyethylene in the concentration range 0. 17o to 107.. in

solvents having varying solubilities for polyethylene. The polyethylene used consists of

fractions of various molecular weights, and the solvent is the mixed-solvent system

xylene-butyl cellosolve, ranging in composition from pure xylene, a good solvent, to 50-50 xylene-butyl cellosolve, which is a very poor solvent.

*This work was supported by the National Science Foundation.

35
5. 13. The Stiructure of Silica Whiskers

H. C. Duecker and W. K. Haller,

Glass Section

Whisker-shaped fibers of silica have been grown by passing a stream of nitrogen,

silicon tetrafluoride, and water vapor over a platinum target heated to 1200°C. X-ray

and electron diffraction studies of the pristine whiskers did not give any indications of

crystallinity, although X-ray diffraction patterns have been obtained for the three main

crystalline forms of silica by devitrifying the whiskers in a proper manner. Electronmicroscopic studies indicate that very young and small whiskers at 50,000 X have much the same appearance during the earliest observable stages of growth as the older and larger

ones have at only 500 X. Since all the above observations, and optical observations as well, indicate an amorphous structure, radial distribution studies of the whiskers are being made using monochromatic X-ray diffraction data. It is hoped that this study will

aid in the determination of possible structural arrangements, thereby making it possible

to assign either an emorphous or transitional structure to the whiskers. From this

assignment it should be possible to obtain a better comparison of the vitreous and

crystalline forms of silica.

5. 14. Structure Models for Amorphous and Crystalline Phases

of Simple Substances

Fred Ordway, Crystal Growth Section

Structure models have been built by a well defined logical process that represents

approximately the real process of condensation. Models with tetrahedral coordination,

built in this way, are crystalline if a minimum nucleus of crystalline structure is

present initially, but are amorphous otherwise. The statistical geometry and topology

of the amorphous models is being studied.

5. 15. Radial-Distribution Studies of Glasses

S. Block and G. J. Piermarini,

Crystallography Section

In connection with a study of immiscibility, models were proposed for the cationmodifier distribution in borate and silicate glasses. On the basis of these models certain

interatomic vectors are expected. X-ray diffraction studies have been used to obtain

independent information about these interatomic vectors. In the past several months

radial-distribution studies of strontium borate glasses, in conjunction with previous

studies on barium- and cadmium-containing glasses (Piermarini and Block, 1963) have indicated a similarity of cation distribution in all these systems. This short-range order is

similar to that found in crystalline BaO. 2B„0„, whose structure has been determined in

this laboratory. Future work is planned to explore the limitations of the similarity of

cation distribution in the vitreous and crystalline states.

6. PARTIAL LIST OF PARTICIPANTS

There follows a partial list of scientists engaged in activities described in this

note, with indications of their research fields and organizational location within the

National Bureau of Standards. The latter may be helpful in making contact with individuals for the purpose of obtaining reprints or further technical information.

Participants at the Washington Laboratories:

AMBLER, Ernest : Ph.D. Oxford University, 1953; nuclear reactions, low temperature

magnetism; Chief, Cryogenics Section, Heat Division. Author Section 4. 10

AMBS, William J. : Ph.D. Catholic University, 1961; corrosion by energetic species, oxide

mono-layer formation; Metal Reactions Section, Metallurgy Division. Author Section 2. 18

36
ALLEN, Harry C. Jr. : Ph.D. University of Washington, 1951; crystal structure; Chief,

Analytical and Inorganic Chemistry Division.

BARBER. David J. : Ph.D. University of Bristol, Bristol, England, 1959; dislocations and

plastic flow in alkali-halide crystals; Physical Properties Section, Inorganic Solids

Division. Author Section 3. 1 BASS. Arnold M. : Ph.D. Duke University, 1949; molecular spectroscopy; Heat

Division. Author Section 4.21

BECKER. James H. : Ph.D. Cornell University, 1957; optical and transport properties of

semiconductors; Atomic Physics Section, Solid State Physics Division. Author Section 4.2

BLOCK, Stanley : Ph.D. Johns Hopkins University, 1955; X-ray crystallography;

Crystallography Section, Inorganic Solids Division. Author Sections 5. 2, 5. 15

BLUNT. Robert F. : Ph.D. Rice University, 1949; optical properties of solids; Solid

State Physics Section, Atomic Physics Division. Author Section 3.12

BOLZ. Leonard H. : X-ray diffraction on frozen vapors and other solid materials;

Physical Properties Section, Inorganic Solids Division.

BOWMAN, Horace A. : Cartesian diver; Mass and Scale Section, Metrology Division.

BROWER, William S. : Verneuil process; Crystal Growth Section,

Inorganic Solids Division, Author Section 2,

1

BROWN, Walter E. : Ph.D. Harvard University, 1949; solubility and crystallography of

calcium phosphate; Dental Research Section, Polymers Division.

BRUMBERGER, Harry : Ph.D. Brooklyn Polytechnic Institute, 1955; low-angle X-ray

scattering, critical phenomena and structure of liquids; Crystal Chemistry Section,

Analytical and Inorganic Chemistry Division. Author Section 5.5

BURLEY, Gordon: Ph.D. Georgetown University, 1962; crystallography of silver iodide;

Crystallography Section, Inorganic Solids Division. Author Section 5.11

CALVERT, Joan P. : Growth of oxide films; Metal Reactions Section, Metallurgy

Division. Author Section 3. 2 CHANG, Te-Tse : Ph.D. University of Colorado, 1962; magnetic resonance; Solid

State Physics Section, Atomic Physics Division. Author Section 4.16

COHEN, Martin I. : X-ray diffraction studies of crystals grown at high temperatures;

Solid State Physics Section, Atomic Physics Division. Author Section 2. 2 COOK, Richard K. : Ph.D. University of Illinois, 1935; acoustics and solid state

physics; Chief, Sound Section, Mechanics Division.

DESLATTES, Richard D. : Ph.D. Johns Hopkins University, 1959; X-ray spectroscopy;

Crystal Chemistry Section, Analytical and Inorganic Chemistry Division. Author Section 3.7

DICKSON, Robert W. : Theory of the effect of homogeneous stress on the symmetry of common oxide structures; optical properties of inorganic solids; Physical Properties

Section, Inorganic Solids Division. Author Sections 3. 11, 4. 14

DUECKER, Heyman, C. : Physical chemistry of glasses; Glass Section, Inorganic

Solids Division. Author Section 5. 13

EARLY, James G. : Ph.D. Rennsalaer Polytechnic Institute, 1963; Kinetics of

Crystallization; Metal Physics Section, Metallurgy Division. Author Section 2.4

EISENSTEIN, Julian C. : Ph.D. Harvard University, 1948; low temperature magnetism;

Cryogenics Section, Heat Division. Author Section 4.8

ESCALANTE, Edward : Field-emission; Metal Reactions Section, Metallurgy

Division. Author Section 2. 18

FARABAUGH, Edward N. : Etch-pits; Crystal Growth Section, Inorganic Solids

Division. Author Section 2, 13 FORMAN, Richard A. : Nuclear and quadrupolar resonance; Solid State Physics

Section, Atomic Physics Division. Author Section 4. 16

FRANKLIN, Alan D. : Ph.D. Princeton University, 1949; properties of point defects

in crystals; Chief, Inorganic Solids Division.

FREDERIKSE, Hans P. R. : Ph.D. Leiden University, Netherlands, 1950; semiconductors

at low temperatures; Chief, Solid State Physics Section, Atomic Physics

Division. Author Section 4.

2

FRENCH, Judson C. : Solid state devices and materials; Electron Devices Section,

Instrumentation Division. Author Section 3.6

FROLEN, Lois J. : Ph.D. Pennsylvania State University, 1963; spectroscopy, crystallography,

microscopy; Pure Substances Section, Analytical and Inorganic Chemistry

Division. Author Section 2.8

37
GLASGOW, Augustus R. : D. Sc. University of Brussels^ 1957; preparation and purification of

polymeric forms, phase equilibria, purity determinations at high pressures; Pure Substances

Section, Analytical and Inorganic Chemistry Division. Author Section 5. 10

GORNICK, Fred : Ph.D. University of Pennsylvania, 1959; physical chemistry of high polymers;

Macromolecules Synthesis and Structure Section, Polymers Division. Author Sections 2.8,5.12.

GRABNER, Ludwig H. : Ph.D. Columbia University, 1950; semiconductors, photoconductivity;

Solid State Physics Section, Atomic Physics Division. Author Section 3. 12 GREENSPAN, Martin : Ultrasonics, mechanics; Sound Section, Mechanics Division.

HALLER, Wolfgang K. : Ph.D. University of Vienna, 1950; physical chemistry of glasses;

Glass Section, Inorganic Solids Division. Author Section 5. 13 HARDY, Stephen C. : Vapor growth of metal crystals; Metal Physics Section, Metallurgy

Division. Author Section 2. 17 HARMAN, George G. : Solid state physics, surface phenomena and electroluminescence;

Electron Devices Section, Instrumentation Division. Author Section 3.6

HIGIER, Theodore : Semiconductor physics; Electron Devices Section, Instrumentation Division.

HOFFMAN. John D. : Ph.D. Princeton University, 1949; dielectrics, nucleation rate of polymer

crystals; Chief, Dielectrics Section, Electricity Division.

HORTON, Avery T. : Crystal growth, impurity retention; Crystal Chemistry Section,

Analytical and Inorganic Chemistry Division. Author Section 2.5

HOWARD, Frank L. : Ph.D. University of Maryland, 1938; Chief, Pure Substances Section,

Analytical and Inorganic Chemistry Division.

HOWARD, Robert E. : Ph.D. Oxford, England, 1957; theoretical physics; Metal Physics

Section, Metallurgy Division. Author Section 2. 16

HUDSON, Ralph P. : Ph.D. Oxford University, 1949; low temperature magnetism; Chief,

Heat Division. Author Section 4.5

KAESER, Robert S. : Low temperature magnetism, cryogenics; Cryogenics Section,

Heat Division. Author Section 4.10

KAHN, Arnold H. : Ph.D. University of California, 1955; band structure of rutile crystals,

studies of paramagnetic impurities in rutile crystals; Solid State Physics Section,

Atomic Physics Division. Author Section 4.6

KHOURY, Fred : Ph.D. Leeds University, 1956; morphology and crystallization of polymers;

Polymer Physics Section, Polymer Division. Author Section 2.6

KRUGER, Jerome : Ph.D. University of Virginia, 1953; corrosion reactions at metal

surfaces; Metal Reactions Section, Metallurgy Division. Author Sections 3.2, 3.4

LaVILLA, Robert E. : Ph.D. Cornell University, 1960; study of transient phenomena by

diffraction techniques; Crystal Chemistry Section, Analytical and Inorganic Chemistry

Division. Author Section 5.4

LEVIN, Ernest M. : Phase equilibria of oxide systems; Crystallography Section,

Inorganic Solids Division. Author Section 5. 1 LIPPINCOTT, Ellis R. : Ph.D. Johns Hopkins University, 1947; infrared spectroscopy;

Crystallography Section, Inorganic Solids Division. Author Section 5. 7 MANGUM, William : Ph.D. University of Chicago, 1961; low temperature magnetism; Cryogenics

Section, Heat Division. Author Section 4.15

MANN, David E. : Ph.D. University of Chicago, 1948; spectroscopy; Chief, Molecular

Spectroscopy Section, Physical Chemistry Division. Author Section 4.22

MARGOSHES, Mairvin : Ph.D. Iowa State University, 1953; spectrographic analysis; Spectrochemistry Section, Analytical and Inorganic Chemistry Division. Author Sections 3.9, 3.10

MARSHAK, Harvey : Ph.D. Duke University, 1955; nuclear reactions, cryogenics; Cryogenics

Section, Heat Division. Author Section 4. 10

MARVIN, Robert S. : Ph.D. University of Wisconsin, 1949; Chief, Rheology Section,

Mechanics Division.

MAUER. Floyd A. : Instrumentation for crystallography; Crystallography Section,

Inorganic Solids Division. Author Section 3. 13 McMURDIE, Howard F. ; Crystallography and chemical phase studies; Chief, Crystallography

Section, Inorganic Solids Division.

McNISH, Alvin G. : Precise density determinations for solid materials; Chief, Metrology

Division.

MILLIGAN, Dolphus E. : Ph.D. University of California, Berkeley, 1958; molecular

spectroscopy; Molecular Spectroscopy Section, Physical Chemistry Division.

NEUMAN, Roslyn C. : Properties of polymers; Dielectrics Section, Electricity

Division. Author Section 2.7

OGBURN, Fielding : Electrochemistry, electrodeposition; Electrolysis and Metal

Deposition Section, Metallurgy Division. Author Section 2. 10

38
ONDIK. Helen M. : Ph.D. Johns Hopkins University, 1957; crystallography, inorganic

chemistry; Crystallography Section, Inorganic Solids Division. Author Section 5.

2

ORDWAY. Fred: Ph.D. California Institute of Technology, 1949; studies in X-ray crystallography; Chief, Crystal Growth Section, Inorganic Solids Division. Author Sections 2. 1, 5.14

OREM, Theodore : Mechanisms of corrosion processes; Metal Reactions Section,

Metallurgy Division. Author Sections 2.3, 2.20

OSER, Hans J. : Ph.D. University of Freiburg, 1957; boundary value problems; Applied

Mathematics Division. Author Section 2. 16

PARETZKIN. Boris : Study of perfection of single crystals by means of X-ray diffraction;

Crystal Chemistry Section, Analytical and Inorganic Chemistry

Division. Author Section 3. 14 PARKER. Robert L. : Ph.D. University of Maryland, 1960; growth of crystals; Metal Physics

Section, Metallurgy Division. Author Sections 2.3, 2.4, 2.9, 2.15, 2.16, 2.17, 3.3

PASSAGLIA, Elio : Ph.D. University of Pennsylvania, 1955; mechanical relaxation processes

in polymers; Polymer Physics Division.

PAYNE. Richard E . : Nuclear resonance; Solid State Physics Section, Atomic Physics

Division. Author Section 4. 16 PEISER, H. Steffen : Crystallography and crystal chemistry; Chief, Crystal Chemistry

Section, Analytical and Inorganic Chemistry Division. Author Sections 3. 14, 4. 14 PERLOFF, Alvin : Structure analysis; Crystallography Section, Inorganic Solids Division.

Author Section 5.

2

PFEIFFER. Earl R. : Crystal growth from solution; Cryogenics Section, Heat Division

Author Section 4.9

PIERMARINI, Gasper J. : Radial distribution studies; high pressure x-ray diffraction

studies; Crystallography Section, Inorganic Solids Division. Author Sections 5.6, 5.15

POLLACK. Gerald L. : Ph.D. California Institute of Technology, 1962; low temperature

physics; Crystal Growth Section, Inorganic Solids Division. Author Sections 2.13,2.14,3.8

POWERS. Joseph : Ph.D. University of Massachusetts, 1961; kinetics, morphology, and

mechanism of crystallization of polymers; Macromolecules Sjmthesis and Structure

Section, Polymers Division. Author Sections 2.7, 3.15, 5.8

PROCTOR, Thomas M. : Solid state physics; Sound Section, Mechanics

Division. Author Section 4. 1 QUINN. Fred A. : Crystallization rate of high polymers; Macromolecules Synthesis and

Structure Section, Polymers Division. Author Sections 3. 15, 5.

8

RASBERRY. Stanley D. : Spectrographic analysis; Spectrochemistry Section, Analytical

and Inorganic Chemistry Division. Author Sections 3.9, 3.10

RAYBOLD, Richard L. : Solid state physics; surface phenomena and electroluminescence;

Electron Devices Section, Instrumentation Division.

READ. Susan F. J. : Ph.D. Oxford University, 1963; solid state physics; Temperature

Physics Section, Heat Division. Author Section 4. 12 ROBBINS. Carl R. : Phase-rule equilibria of inorganic systems; Crystallography

Section, Inorganic Solids Division.

ROBERTS. D. Ellis : Crystal growth; Solid State Physics Section, Atomic Physics

Division. Author Section 2.

2

ROBINSON. Henry E. : Thermal conductivity measurement on solids at high and low

temperatures; Chief, Heat Transfer Section, Building Research Division.

ROSS, Gaylon S. : Nucleation, crystal growth; Pure Substances Section, Analytical and

Inorganic Chemistry Division. Author Section 2.8

ROTH, Robert S. : Ph.D. University of Illinois, 1951; X-ray diffraction studies in

connection v/ith phase equilibria; Crystallography Section, Inorganic Solids

Division. Author Section 5.

1

RUBIN. Robert J. : Ph.D. Cornell University, 1951; theoretical chemical physics;

Heat Division. Author Section 4.

7

RUBIN. Sherwin : Hall-effect devices and materials; Engineering Electronics Section,

Instrumentation Division. Author Section 4.3

RUFF. Arthur W. : Dislocations and etch pits; Metal Physics Section, Metallurgy

Division. Author Section 2.21

RUTHBERG. Stanley : Materials and physics of vacuum devices; Electron Devices Section,

Instrumentation Division.

SAYLOR. Charles P. : Ph.D. Cornell University, 1928; precise physical characteristics

of compounds, accurate microscopic measurements of optical properties; Analytical and

Inorganic Chemistry Division.

39
SCHAFFT, Harry A. : Semiconductor devices and breakdown phenomena; Electron Devices

Section^ Instrumencation Division. Author Section 3.6

SCHNEIDER, Samuel J. : Phase equilibria of oxide systems and metal oxide melting point

standards; Crystallography Section, Inorganic Solids Division. Author Section 4.13

SCHOOLEY. James F. : Ph.D. University of California, 1961; crystal growth for lowtemperature paramagnetic studies; Cryogenics Section, Heat Division. Author Section 4,9

SCHOONOVER. Irl C. : Ph.D. Princeton University, 1933; research administration; NBS

Director's Office.

SCHROEDER, Rudolph A. : Ph.D. University of Maryland, 1957; infrared spectroscopy;

Crystallography Section, Inorganic Solids Division. Author Section 5. 7 SCRIBNER, Bourdon F. : Analytical applications of optical and X-ray spectroscopy; Chief,

Spectrochemistry Section, Analytical and Inorganic Chemistry Division. Author Section 3.9,3.10

SIMMONS, John S. : Ph.D. University of California, 1961; mathematical physics;

Director's Office. Author Section 2.16

SPINNER, Sam : Elastic properties of inorganic solids; Physical Properties Section,

Inorganic Solids Division. Author Section 3. 5 STRASSBURGER, John : Crystal growth from solution; Crystal Chemistry Section, Analytical

and Inorganic Chemistry Division. Author Section 2.5

SWANSON, Howard E. : Physical chemistry. X-ray diffraction; Crystallography Section,

Inorganic Solids Division. Author Section 5.3

SWARTZENDRUBER, Lydon J. : Solid state physids; Electron Devices Section, Instrumentation

Division. Author Section 3.6

TIGHE, Nancy : Defects by means of electron microscopy of non-metallic crystals;

Physical Properties Section, Inorganic Solids Division, Author Section 3. 1 TORGESEN, John L. : Ph.D. Columbia University, 1942; crystal growth, impurity retentions,

crystal properties; Crystal Chemistry Section, Analytical and Inorganic Chemistry

Division. Author Section 2.5

THURBER, Willis R. : Thermoelectricity; Solid State Physics Section, Atomic Physics

Division.

VACHER, Herbert C. : X-ray diffraction; Metal Physics Section, Metallurgy Division

Author Section 2. 3 VAN VALKENBURG, Alvin : High pressure transitions; Crystallography Section, Inorganic

Solids Division. Author Section 5.9

WACHTMAN, John B. : Ph.D. University of Maryland, 1961; mechanical and electrical

properties of crystals; Physical Properties Section, Inorganic Solids

Division. Author Sections 3.5, 4.14

WAGNER, Timothy : Growth and evaporation of whiskers; Metal Physics Section,

Metallurgy Division. Author Section 2. 15

WASILIK, John H. : Ph.D. Catholic University, 1956; dielectric constant and losses,

ultrasonics; Solid State Physics Section, Atomic Physics Division. Author Section 4.4

WEIR, Charles E. : Infrared spectroscopy and high pressure physics; Crystallography

Section, Inorganic Solids Division. Author Sections 5.6, 5,7

WILL, Richard S. : Electron-field emission; Electron Physics Section, Atomic Physics

Division. Author Section 4.20

YOLKEN, Howard T. : Growth of oxide films; Metal Reactions Section, Metallurgy

Division. Author Section 3. 2 YOUNG, Russell D. : Ph.D. Pennsylvania State University, 1959; surface physics,

particularly with the field-emission microscope; Electron Physics Section, Atomic

Physics Division. Author Sections 4. 19, 4. 20

Participants in the Boulder Laboratories:

COOK, Alan R. : Physical instrumentation; Radio and Microwave Materials Section,

Radio Standards Physics Division. Author Section 4.17

DALKE, John L. : The characterization of materials at radio frequencies; Chief, Radio

and Microwave Materials Section, Radio Standards Physics Division.

GRUZENSKY, Paul M. : Ph.D. Oregon State College, 1959; physical chemistry and high

purity materials; Radio and Microwave Materials Section, Radio Standards Physics

Division. Author Section 2. 12 GUNTNER, Charles S. : Imperfections, flow and fracture, phase transformations;

Properties of Materials Section, Cryogenics Engineering Laboratory. Author Section 2.11

40
JEFFERSON. Clinton F. : Ph.D. University of Michigan, 1959; solid state solutions for ferrimagnetic characteristics; Radio and Microwave Materials Section, Radio Standards Physics

Division.

MATARRESE, Lawrence M. : Ph.D. University of Chicago, 1954; solid state physics, EPR and

other resonance spectroscopy related to solid state mechanisms; Radio and Microwave

Materials Section, Radio Standards Physics Division. Author Section 4. 17 REED, Richard P. : Imperfections, flow and fracture, phase transformations; Properties of

Materials Section, Cryogenics Engineering Laboratory. Author Section 2. 11 RISLEY, Alan S. : Magnetism and ferrites; Radio and Microwave Materials Section, Radio

Standards Physics Division. Author Section 4. 18

WELLS. Joseph S. : Microwave physics, solid state physics as it relates to ENDOR and NMR; Radio and Microwave Materials Section, Radio Standards Physics

Division. Author Section 4. 17

LITERATURE REFERENCES

R. L. Anderson and R. L. Parker (1963); Evaporation of Potassium Whiskers, Bull. Am. Phys.

Soc. 8, p. 393.

D. J. Barber (1963); Electron-Microscope Studies of Aluminum-Oxide Whiskers, Program, August

Meeting, Electron Microscope Society of America (to be reprinted in J. Appl. Phys. ).

D. J. Barber and N. J. Tighe (1963); Dislocations and Etch Pits in Sapphire and Ruby,

Program, August Meeting, Electron Microscope Society of America (to be reprinted in J. Appl.

Phys. ).

J. H. Becker and W. R. Hosier (1963); Electron Energy Levels and their Relationship to Lattice Defects to Reduced Rutile; Proceedings of the International Conference on Crystal

Lattice Defects. 1962. Journal of the Physical Society of Japan 18, Supplement II, p. 152.

S. Block and A. Perloff (1963-64); The Direct Determination of the Crystal Structure of

NaB(OH), . 2H 0, Acta Cryst. (accepted).

H. E. Bond and K. B. Harvey (1963); The Decoration of Dislocations in Aluminum Oxide; J. Appl. Phys. 34, (2) p. 440.

G. Burley (1963a); The Photolytic Behavior of Silver Iodide, J. Research Nat'l Bur. Standards 67A. (4) (accepted).

G. Burley (1.963b); The Structure of Hexagonal Silver Iodide, J. Chem. Phys. 38, p. 2807.

5+

T. Chang (1963); The EPR Spectrum of Mo in TiO- ; submitted to the American Physical

Society for presentation at the Edmonton, Canada, meeting, August 28-31.

D. M. Eagles (1963); Exponential Optical Absorption Edges in the Alkali Halides; Bulletin

of the American Physical Society Series II, 8^ No. 3, Abstract.

E. D. Eanes and Helen M. Ondik (1962); The Structure of Lithium Dipotassium Trimetaphosphate,

Acta Cryst. 15, p. 1280.

P. H. Fang and W. S. Brower (1963a); Dielectric Constant of Cr„0 Crystals, Phys, Rev. 129.

p, 1951.

P. H, Fang and W. S. Brower (1963b); A Note on Domain Conversion of BaTiO , J. Appl. Phys.

34, (5) p. 1516.

-^

R. A. Forman (1963); Nitrogen NMR Chemical Shifts in the Azide Ion; J. Chem. Phys. (accepted)

R. A. Forman and D. R. Lide, Jr. (1963); Quadrupole Coupling Constants from the Microwave

Spectrum of Hydrazoic Acid, J. Chem. Phys. (accepted).

H. P. R. Frederikse (1963); editor and part author of Section 9, Solid State Physics,

AIP Handbook; McGraw-Hill Book Company.

41
G. G. Harman, R. L. Raybold, and 0. L. Meyer (1963); Direct Observation of Charge Storage

in the Surface States of Silicon, J. Appl. Phys. 34. p. 380.

W. C. Hernandez, Jr. and A. H. Kahn (1963); A Note on the Galvanomagnetic and Thermoelectric Coefficients of Tetragonal Crystalline Materials, J. Research, Nat ' 1 Bur. Standards. (accepted).

J. Kruger (1963); Optical Studies of the Formation and Break Down of Passive Films Formed

on Iron Single Crystal Surfaces in Inorganic Inhibitor Solutions, J. Electrochem. Soc. , 110 . p. 654.

M. Margoshes and B. F. Scribner (1963); Excitation of Solutions in Gas-stabilized Arc

Sources, Actes du IX Colloquium Spectroscopicum Internationale, G. A.M.S., Paris, 2, p. 309.

H. S. Peiser, J. B. Wachtman, Jr., and R, W. Dickson (1963); Reduction of Space Group to Subgroups by Homogeneous Strain, J. Research, Nat'l Bur, Standards 67A. (accepted).

A. Perloff (1963-64); The Crystal Structure of 1-Ethyldecaborane, Acta Cryst. (accepted).

G. J. Piermarini and S. Block (1963); Radial Distribution Study of Vitreous Barium

Borosilicate, J. Research, Nat'l Bur. Standards 67A. (1) p. 37.

G. J. Piermarini and C. E. Weir (1962a); High Pressure Transitions in RbF, J. Chem. Phys.

37, (8) p. 1887.

G. J. Piermarini and C. E. Weir (1962b); A Diamond Cell for X-Ray Diffraction Studies at High Pressures, J. Research, Nat'l Bur. Standards 66A, (4) p. 325.

G. L. Pollack (1964); Absorption Spectra of Diatomic Molecules in Liquid and Crystalline

Rare Gases, Advances in Applied Spectroscopy. Plenum Press, New York.

G. L. Pollack and H. P. Broida (1963a); Vapor Snakes in Solid Argon, J. Chem. Phys. 38,

p. 968.

G. L. Pollack and H. P. Broida (1963b); Absorption Spectra of NO in Crystalline and Liquid

Krypton, J. Chem. Phys. 38, p. 2012.

G. L. Pollack and E. N. Farabaugh (1963); Thermal Etching of Crystalline Argon, Bull. Am. Phys. Soc. 8, p. 227.

F. A. Quinn, Jr. and J. Powers (1963) ; Measurements of a Maximum in the Isothermal

Crystallization Rate Temperature Curve for Polypentene-1, Journal of Polymer Science - Part B.

R. S. Roth, J. L. Waring, and E. M. Levin (1963); Polymorphism of ABO -Type Rare Earth

Borate Solid Solutions, Rare Earth Research - Proceedings of the Third Conference . Gordon

and Breach, New York.

R. J. Rubin (1963); Numerical Computation of Time Dependent Properties of Isotopically

Disordered One-Dimensional Harmonic Crystal Lattices, Proceedings of the International

Conference on Crystal Lattice Defects. 1962. Journal of the Physical Society of Japan 18 . Supplement II, p. 63.

S. Ruthberg, M. W. Barnes, and R. H. Noyce (1963a); Alteration of the Muscovite Absorption

Spectrum by KBr Pellet Preparation, Applied Optics 2^ p. 177.

S. Ruthberg, M. W. Barnes, and R. H. Noyce (1963b); Correlation of Muscovite Sheet Mica on

the Basis of Color, Apparent Optic Angle, and Absorption Spectrum, J. Research, Nat'l Bur. Standards 67A. (accepted).

S. J. Schneider (1963); Compilation of the Melting Points of the Metal Oxides . Nat'l Bur. Standards Monograph 68^.

42
S. J. Schneider and J. L. Waring (1963); Phase Equilibrium Relations in the Sc . Ga_0

System, J. Research, Nat ' 1 Bur. Standards 67A. (1) p. 19.

J. F. Schooley and D. D. Hoppes (1962); The Gamma Ray Distribution from Oriented Cerium-141

and its Application to Thermal Contact at Low Temperature, Proceedings of the 8th Inter - national Conference on Low Temperature Physics . Queen Mary College, London.

J. F. Schooley, D. D. Hoppes, and A. T. Hirshfeld (1962); The Gamma-Ray Distribution from

Oriented Cerium-141, J. Research, Nat'l Bur. Standards 66A, p. 317.

R. A. Schroeder, C. E. Weir, and E. R. Lippincott (1962); Lattice Frequencies and

Rotational Barriers for Inorganic Carbonates and Nitrates for Low Temperature Infrared

Spectroscopy, J. Research, Nat'l Bur. Standards 66A, (5) p. 407.

J. Strassburger and J. L. Torgesen (1963); Oxalic Acid/Water; Its Significance in Oxalic

Acid Crystal Growth, J. Research, Nat'l Bur. Standards 67A, (4) p. 347.

H. E. Swanson, M. C. Morris, R. P. Stinchfield, and E. H. Evans (1963); Standard X-Ray

Diffraction Powder Patterns. Nat'l Bur. Standards Monograph ^ Section 2.

L. J. Swartzendruber (1963); Applications of a Semiconductor Surface-State Charge-Storage

Device, Solid State Electronics 6^, p. 59.

A. Van Valkenburg (1963); High Pressure Microscopy, High Pressure Measurement, Butterworth,

Inc. Washington, D. C.

A. Van Valkenburg and J. Powers (1963); Optical Observations of Pressure Induced Transitions

in Polymers, J. Appl. Phys. 34, p. 2433.

J. B. Wachtman, Jr. (1963); Mechanical and Electrical Relaxation in ThO„ Containing CaO,

Phys. Rev. 131. No. 2.

J. B. Wachtman, Jr., H. S. Peiser, and E. P. Levine (1963); Symmetry Splitting of Equivalent

Sites in Oxide Crystals and Related Mechanical Effects, J. Research, Nat'l Bur. Standards

67A. p. 281.

J. B. Wachtman, Jr., W. E. Teeft, and D. G. Lam, Jr. (1962); Elastic Constants of Rutile

(TiO ), J. Research, Nat'l Bur. Standards 66A. p. 465.

J. B. Wachtman, Jr., Mary L. Wheat, and S. Marzullo (1963); A Method for Determining the

Elastic Constants of a Cubic Crystal from Velocity Measurements in a Single Arbitrary

Direction; Application to SrTiO., J. Research, Nat'l Bur. Standards 67A, p. 193.

J. Yahia (1963); Dependence of the Electrical Conductivity and Thermoelectric Power of

Pure and Aluminum-Doped Rutile on Equilibrium Oxygen Pressure and Temperature, Phys. Rev.

130. p. 1711.

43

a U. S. GOVERNMENT PRINTING OFFICE : 1963 O - 704-885

U. S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

NATIONAL BUREAU OF STANDARDS

A."V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C.,and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineeringin the field indicated by

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the

front cover.

WASHINGTON, D. C.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. Magnetic Measurements.

Dielectrics. High Voltage. Absolute Electrical Measurements.

Metrology. Photometry and Colorimetry. Refractometry. Photographic Research. Length. Engineering Metrology. Mass and Volume.

Heat. Temperature Physics. Heat Measurements. Cryogenic Physics. Equation of State. Statistical Physics.

Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

Nucleonic Instrumentation. Neutron Physics.

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Standard Refer- ence Materials. Applied Analytical Research. Crystal Chemistry. Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Controls. Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. Polymer Physics. Polymer Characterization. Polymer Evaluation and Testing. Applied Polymer Standards and Research. Dental Research.

Metallurgy. Engineering Metallurgy. Metal Reactions. Metal Physics. Electrolysis and Metal Deposition.

Inorganic Solids. Engineering Ceramics. Glass. Solid State Chemistry. Crystal Growth. Physical Properties.

Crystallography.

Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials. Codes and Safety Standards. Heat Transfer. Inorganic Building Materials. Metallic Building Materials. Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Operations Research. Data Processing Systems. Components and Techniques. Computer Technology. Measurements Automation. Engineering Applications. Systems Analysis.

Atomic Physics. Spectroscopy. Infrared Spectroscopy. Far Ultraviolet Physics. Solid State Physics. Electron Physics. Atomic Physics. Plasma Spectroscopy.

Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation. Physical Chemistry. Thermochemistry. Surface Chemistry. Organic Chemistry. Moleculsir Spectroscopy. Ele- mentary Processes. Mass Spectrometry. Photochemistry and Radiation Chemistry.

Office of Weights and Measures. BOULDEK, COLO.

CRYOGENIC ENGINEERING LABORATORY

Cryogenic Processes. Cryogenic Properties of Solids. Cryogenic Technical Services. Properties of Cryogenic

Fluids. CENTRAL RADIO PROPAGATION LABORATORY

Ionosphere Research and Propagation. Low Frequency and Very Low Frequency Research. Ionosphere Research. Prediction Services. Sun- Earth Relationships. Field Engineering. Radio Warning Services. Vertical Soundings Research. Troposphere and Space Telecommunications. Data Reduction Instrumentation. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Spectrum Utilization Research. Radio-Meteorology. Lower Atmosphere

Physics.

Radio Systems. Applied Electromagnetic Theory. High Frequency and Very High Frequency Research. Fre- quency Utilization. Modulation Research. Antenna Research. Radiodetermination. Upper Atmosphere and Space Physics. Upper Atmosphere and Plasma Physics. High Latitude Ionosphere

Physics. Ionosphere and Exosphere Scatter. Airglow and Aurora. Ionospheric Radio Astronomy.

RADIO STANDARDS LABORATORY

Radio Standards Physics. Frequency and Time Disseminations. Radio and Microwave Materials. Atomic Fre- quency and Time-Interval Standards. Radio Plasma. Microwave Physics.

Radio Standards Engineering. High Frequency Electrical Standards. High Frequency Calibration Services. High

Frequency Impedance Standards. Microwave Calibration Services. Microwave Circuit Standards. Low Frequency

Calibration Services.

Joint Institute for Laboratory Astrophysics -NBS Group (Univ. of Colo.).
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NBS