bluuebunny/crossref_metadata_2025 huggingface dataset:
MINERALOGY OF TYPICAL NORTH CAROLINA CLAYS AND SHALES*
Authors: Fabianic W. L. , Stoltb N. H.
Published: July 2010

A microscopic examination was made on those clays and shales of North Carolina which gave most promise of future development in the structural clay products industry. The more common minerals were determined rather than the rare ones which did not occur in sufficient quantity to affect the quality of the clay. The work showed clay substance to be the most abundant material present, followed by quartz, red and yellow iron oxides, muscovite through sericite to hydromica, and epidote, with smaller amounts of rutile, biotite, titanite, tourmaline, and zircon. Diatoms were found in two cases and kaolinite in one.
CONSTITUTION AND THERMAL EXPANSION OF SILICA COKE‐OVEN BRICK AFTER SERVICE*
Authors: Austin J. B. , Piercs R. H. H.
Published: July 2010

Two silica brick which were in service in a coke oven for over ten years have been examined under the petrographic microscope. At the flue side the brick were almost completely converted to cristobalite, next comes a relatively thick layer which is mainly tridyinite, and finally mar the coke side quartz is found in addition. Measurements on small specimens taken from one of the brick show that the several layers have very different expanions. I t is concluded that in cooling a battery of ovens great care should be taken to cool slowly through the temperature range 200 to 300deg;C.
SELENIUM RUBY GLASS: PREPARATION AND X‐RAY STUDY*
Authors: Bigelow Maurice H , Silverman Alexander
Published: July 2010

A study has been made of color produced by selenium and accessory substances in sodium oxide‐zinc oxide‐silica glasses. Most desirable reds were obtained by adding selenium, cadmium sulfide, arsenic trioxide, and carbon to a foundation batch. X‐ray examination indicates that the red color produced is probably due to a solid solution of CdS in CdSe.
A LOW‐TEMPERATURE COMPARATOR FOR COEFFICIENT OF EXPANSION OF CERAMIC BODIES*
Authors: Davis H. E.
Published: July 2010

The following paper describes the design and operation of a simple device for determining the coefficient of linear expansion of fired clays or body mixtures between room temperature and 300°C, in view of predetermining their adaptability to a satisfactory glaze fit.
DE‐AIRING STIFF‐MUD BODIES BY MEANS OTHER THAN THE VACUUM METHOD*
Authors: Straight H. R.
Published: July 2010

A new design of auger blades and pug‐mill knives which avoid working air into the clay mass during tcinpering and forming is presented.
SOME PROPERTIES OF ENGLISH CHINA CLAYS*
Authors: Klinefelter T. A. , Meyer W. W. , Vaciiuska E. J.
Published: July 2010

A study is presented of soinc of the propcrtics of fiftecn English china clays in common use comrncrcially in the United States. Data are presented which may be useful in making substitutions for these clays, as well as furnishing a basis of correlation of some of the properties. A study of the base exchange capacities shows a general relationship to the transverse strciigths of the clays in the uiifired state.
EFFECT OF ZINC OXIDE ON SHEET‐IRON COVER‐ENAMEL PROPERTIES*
Authors: Fetterolf L D
Published: July 2010

The effect of ZnO on sheet‐iron cover‐enamel properties was studied by evaluation of the propcrties of a typical sheet‐iron cover enamel in which ZnO was used as single‐ and double‐partial replacements for the various ingredients. The fluxing action of ZnO was found to bc pronounced and i i was markedly effective in decreasing frit solubility in the mill liquor. Improvement in gloss resulted from its use without any adverse effect on enamel extensibility and resistance to thermal shock.
COLOR CHANGES IN FLINT GLASS*
Authors: Lyle A. K. , Sharp Donald E.
Published: July 2010

Decolorized glasses vary in their approach to neutral color depending upon their use and custom of manufacture. Iron, the chief coloring agent in colorless glass, produces several colors. The iron color is first controlled and then neutralized with its complementary color or colors furnished by a variety of oxides. The final tint may be neutral or not, depending upon the method of examination, and varies with changing conditions.

The decolorizing materials are subject to change after the glass is made. These changes are caused by heat and light radiations. Much research on color change is incomplete. The glass composition should be accurately known and the color should be represented by spectral transmissions.
A PECULIARITY OF SHEET‐IRON ACID RESISTING COVER COAT ENAMELS*
Authors: Ebright H. E. , Hansen J. E.
Published: July 2010

It has been demonstrated that the small bare spots evident in the first coat of acid‐resisting enamel applied directly upon the ground coat are not necessarily the result of a process fish scaling in the ground coat during the firing operation, but are more often the result of reboiling of the ground‐coat enamel and lack of film strength in the yet unfused layer of acid‐resisting enamel. Reboiling, or other mechanical movements of the ground coat, may promote defects in acid‐resisting enamels which would not be visible in those of the nonacid‐resisting type, particularly when these enamels are applied directly upon the ground coat. The electrolytes used with acid‐resisting enamels are directly connected with the popping condition noted. A choice of the proper kinds and amounts of electrolytes for “setting‐up” the enamel can, in some cases, eliminate or minimize this trouble. The use of a nonacid‐resisting enamel, properly set up as an intermediate layer between the ground coat and the finish coat of acid‐resisting enamel, will also prevent troubles of this kind. The tendency for this peculiar defect to occur depends also upon the type of enameling base metal used and its tendency to reboil.
NOTES ON THE X‐RAY DIFFRACTION PATTERNS OF MULLITE*
Authors: Posnjak E. , Greig J. W.
Published: July 2010

A wide range of artificial alumina‐silica products has been examined by the X‐ray powder method. In each case in which the pattern has been sufficiently clear to permita decision the pattern has been that of mullite, not that of sillimanite. The examination included a number of preparations made by heating clay minerals and clays at 1000°.

Mullite crystals containing alumina or the oxides of iron or titanium in solid solution give diffraction patterns in which the lines are slightly displaced toward the origin with respect to the corresponding lines in the diffraction pattern of the standard mullite (3A12O3.2SiO2).

Mullite crystals, freed by HF treatment from the matrix in which they grew, often give diffraction patterns in which the intensities of certain lines are strikingly different from normal. This is due to the orientation of the minute elongated crystals when mounted for photographing.

Finally, two recent papers proposing special names for certain similar materials are discussed and, on the basis of published data and the evidence presented here, these proposals are found to be unwarranted.
TESTS OF REINFORCED BRICK COLUMNS*
Authors: Lyse Inge
Published: July 2010

This paper presents the data obtained in an extensive investigation on reinforced brick columns. The results furnished a basis for the development of rational design formulas. The strengths of the columns were found to be made up of the effective strength of the masonry plus the yield‐point strength of the longitudinal reinforcement. A study of the type of masonry mortars revealed the fact that Portland cement mortar containing 15% ordinary brick clay by weight of the cement gave better results than did any of the other types used.

A review of all known‐experiments on brick piers and columns is given.
SELECTION OF CLAYS FOR SAGGERS OF PREDETERMINED RESISTANCE TO THERMAL SHOCK AND PREDICTION OF SAGGER LIFE IN SERVICE*
Authors: Heindl R. A. , Mong L. E.
Published: July 2010

A series of twelve sagger bodies having a wide range in properties was prepared from fourteen different clays and grog made, in most instances, from the same clays. Experimental saggers heated to different temperatures were tested for resistance to thermal shock and the values compared with predetermined values assigned to each of the bodies. A chart was prepared which shows the relation between modulus of rupture, modulus of elasticity, linear thermal expansion, and resistance of saggers to thermal shock.
REFRACTORY PROBLEMS IN PRODUCTION OF HYDROGEN BY PYROLYSIS OF NATURAL GAS*
Authors: Wright R. E. , Wolff H. I.
Published: July 2010

Abstract

The severe attack of the refractory checkerwork in a regenerative furnace was encountered at temperatures over 2500°F. Pilot‐plant tests, supplemented by a laboratory investigation, were made of silicate refractories varying in alumina content from 0 to 70%.

These tests indicate that the attack was primarily caused by the reduction, to a volatile form, of free and combined silica by carbon. This left a granular residue of mullite and/ or corundum, depending on the original alumina content. Secondary reactions occurred, the most notable of which was the recombination of the corundum with locally deposited silica to form secondary mullite.

The laboratory test showed that carbon reacted with mullite at a temperature as low as 2470°F. A petrographic study has shown that the decomposition of the refractory material takes place in well‐defined stages from the initial removal of free silica to the breakdown of mullite. The rate of decomposition increases with temperature.
METHOD OF CORRELATING CHEMICAL COMPOSITION RELATIVE AMOUNTS OF GLASSY BOND AND PROPERTÍES OF CERAMIC BODIES*
Authors: Shelton Georgb Reed
Published: July 2010

Abstract

A method is given for correlating the chemical composition, relative amounts of glassy bond, and properties of fired ceramic bodies. The procedure consists of (1) plotting the compositions expressed in simplified terms on a reference diagram and (2) plotting data on the physical properties vertically from the plane of the reference diagram. Because the reference diagram contains the appropriate equilibrium diagram, the quantities of liquid and crystalline phases calculated for preparations of pure raw materials heated to equilibrium at a given temperature are useful (1) in estimating the relative quantities of glassy bond in fired bodies and (2) in differentiating fired bodies with respect to phase constituents. Data on fired whiteware are used to illustrate the relation of composition to the following properties: porosity, shrinkage, dielectric strength, and specific gravity.
Measurement of the Torsion Properties of Alumina and Zirconia at Elevated Temperatures
Authors: STAVROLAKIS J. A. , NORTON F. H.
Published: July 2010

A precise instrument for measuring the torsion properties of refractories up to temperatures of 1500°C. is described. The twist is measured by sapphire mirrors mounted on the specimen itself. The mechanical properties of dense alumina and dense stabilized zirconia were measured at various temperatures. Higher ultimate strengths were reached than those reported for other bodies.
The Systems Zirconia‐Lanthana and Zirconia‐Neodymia
Authors: BROWN FRANK H. , DUWEZ POL
Published: July 2010

The minimum amounts of lanthana and neodymia required to stabilize zirconia into a cubic form are 30 and 20 mole %, respectively, at 980°C. X‐ray diffraction studies have established the upper limit of the two cubic solid solution regions as approximately 40 mole %. This stabilized region of the phase diagrams broadens slightly in each system as the temperature of heat‐treatment is raised. Based on experimental evidence obtained by X‐ray diffraction and dilatometric methods, phase diagrams for the systems zirconia–lanthana and zirconia–neodymia are proposed.
Polarographic Analysis for Cadmium, Zinc, and Lead in Glass
Authors: WILLIAMS J. P. , SCHWENKLER T. A.
Published: July 2010

The cadmium, zinc, and lead content in glass can be rapidly estimated with a polarograph. These analyses usually can be carried out without making chemical separations, since interfering elements are seldom found in common glass compositions. The mean difference in absolute per cent between chemical and polarographic results for a series of thirteen glasses containing cadmium and/or zinc and for a series of twelve lead glasses is approximately 0.3% for PbO, 0.05% for CdO, and 0.1% for ZnO.
The Structure of Glasses
Authors: HUGGINS MAURICE L.
Published: July 2010

A theory of the structure of glasses is presented. It is assumed that the volume and various other properties can be computed additively from contributions characteristic of the types of “structon” present, a structon being defined as an atom surrounded by close neighbors in a specific way. If the possible types of structon differ enough in stability, the number of such types present in appreciable quantities in a sample at equilibrium is small. If it is the minimum number required to give the correct over‐all composition, the sets of structon types present change suddenly as the composition changes. This explains the observed fact that certain property‐composition curves consist of straight‐line segments, with sharp breaks between them. Detailed consideration is given to the volumes (and densities) of well‐annealed sodium silicate glasses. Reasonable sets of structon types account quantitatively for the locations of the observed breaks. Certain definite conclusions are drawn regarding the types of structon present in the different composition ranges, their relative numbers, and their contributions to the total volume.
Viscometer for Measuring Glass Viscosity by Means of Flow Through an Orifice
Authors: TIEDE R. L.
Published: July 2010

A method is described by which the viscosity of glass can be estimated in the range 100 to 450 poises by determining the relationship between temperature and the quantity of glass in fiber form which can be drawn from an orifice in unit time. Results are based on a comparison with an arbitrarily chosen standard glass. The method is relatively rapid, yields good precision, and can be used to make samples of fibers valuable for other tests.
Some Physical Factors Affecting the Internal Damping of Glass
Authors: BLUM S. L.
Published: July 2010

An apparatus for accurately measuring the internal damping of fine fibers in vacuo at constant temperature is described. The effects of handling, hydrofluoric acid etch, fiber diameter, and other factors on the internal damping values for a typical soda‐lime‐silica glass are discussed. The effects of viscous air damping and vacua on torsional oscillation in this apparatus also are discussed since absolute internal damping values were desired.
Improved High‐Q Dielectric Resonator with Complex Perovskite Structure
Authors: Tamura Hiroshi , Konoike Takehiro , Sakabe Yukio , Wakino Kikuo
Published: July 2010

Microwave characteristics of the system Ba(Zn1/3Ta2/3)O3‐BaZrO3 were investigated. Ba(Zn,Ta)O3 has a perovskite pseudocell and hexagonal superstructure; the superstructure was not formed after addition of BaZrO3. Both sintering and crystallization of Ba(Zn,Ta)O3‐BaZrO3 were accelerated compared to those of Ba(Zn,Ta)O3 alone, and the microwave Q value was also improved. The material optimized for the dielectric resonator, Ba(Ni,Ta)O3‐Ba(Zr,Zn,Ta)O3, has a dielectric constant of 30, Q value of 10000 at 10 GHz, and temperature coeficient of resonant frequency of 0 ppm/°C.
Sintering of Bimodally Distributed Alumina Powders
Authors: SMITH J. P. , MESSING G. L.
Published: July 2010

The densification of alumina powders prepared to have a bi‐modal particle‐size distribution with a coarse‐to‐fine particle‐size ratio of ≊ 10 can be predicted to a first approximation if the densification of the fine and coarse powders is known. Deviations from model prediction were attributed to compositional heterogeneity. Microstructural observations of bimodal powders show that only the fine powder undergoes grain growth. Thus, the grain‐size distribution becomes more uniform than the initial particle‐size distribution.
Kinetics of Hot‐Pressing: The Semilogarithmic Law
Authors: VIEIRA J. M. , BROOK R. J.
Published: July 2010

A proportionality has often been observed between the density of a sample during sintering and hot‐pressing and the logarithm of the sintering time; this has usually been explained as the consequence of grain growth occurring during the densification. An alternative explanation is given for the case of hot‐pressing under conditions where densification is brought about by plastic flow (dislocation creep); this explanation is based on a stress multiplication factor which is exponentially dependent on the porosity. The exponential form of stress concentration factor can originate where rapid mass transport near the pores allows the development of an equilibrium micro‐structural configuration. Important consequences of this model result for the interpretation of hot‐pressing kinetics; experimental support for the model has been found in the hot‐pressing of high‐purity magnesium oxide.
Temperature‐Stable Dielectrics Based on Chemically Inhomogeneous BaTiO3
Authors: HENNINGS D. , ROSENSTEIN G.
Published: July 2010

The dielectric properties and chemical homogeneity of BaTiO3 ceramics sintered with additions of the pseudophase “CdBi2Nb2O9” were investigated using SEM, TEM, STEM, and EDX. In materials showing the “X7R” dielectric temperature characteristic, the microstructure exhibits the grain core‐grain shell structure. The perovskite material in the shell shows a temperature characteristic determined by mixed crystals of BaTiO3 with the complex perovskites Ba(Bi1/2Nb1/2)O3 and Ba(Cd1/3Nb2/3)O3 having an approximate Curie point of ‐80°C. The chemical inhomogeneity emerges during a process of reactive liquid‐phase sintering. Application of too‐high sintering temperatures leads to uniform distributions of the additives via solid‐state diffusion and to the loss of the X7R characteristic.
Microwave Characteristics of (Zr, Sn)TiO4and BaO‐PbO‐Nd2O3‐TiO2Dielectric Resonators
Authors: WAKINO K. , MINAI K. , TAMURA H.
Published: July 2010

The microwave characteristics of two dielectric resonator materials were investigated. This research included (Zr, Sn)TiO4, a material having the characteristics of a dielectric constantK= 38,Q= 7000 at 7 GHz, and temperature coefficient of resonant frequencyτf, = 0 ppm/°C. The investigation determined the relations between the dielectric loss and micro‐structures of this ceramic. Analysis by X‐ray microanalyzer made it clear that the addition of Fe2O3increased the dielectric loss of this ceramic because the Fe ions diffused into the grain. The other material investigated was BaO‐PbO‐Nd2O3‐TiO2, a ceramic having a dielectric constant ofK= 88,Q= 5000 at 1 GHz, andτf= 0 ppm/°C. As this ceramic has a very high dielectric constant, it is useful for applications at frequencies <1 GHz.
Leaching of Glasses with Molar Composition 20Na2O · 10RO ·x Al2O3· (70‐x)SiO2
Authors: SMETS BRUNO M. J. , THOLEN MARGRIET G. W.
Published: July 2010

Sodium depth profiles were determined in water‐leached glass samples with molar composition 20Na2O · 10RO ·x Al2O3· (70 ‐ x)SiO2 (RO = CaO, MgO, and ZnO) using secondary ion mass spectrometry. The leaching of sodium ions decreases with increasing Al2O3 content in all three glass systems. For x= 0 the leaching is hardly affected by the nature of the divalent cation. For x= 5 and 10 the corrosion resistance is highest for the glass containing ZnO, and for the glasses containing ZnO and MgO, respectively. These glasses correspond to those with the smallest fraction of NBOs. From all these results it is concluded that the nonbridging oxygen atoms play an important role in promoting the leaching of a glass.
Energy and Structure of (001) Coincident‐Site Twist Boundaries and the Free (001) Surface in MgO: A Theoretical Study
Authors: WOLF D.
Published: July 2010

A computer code is described which permits investigation of the energy and structure of coincident‐site lattice (CSL) grain boundaries, stacking faults, and free surfaces in ionic crystals. The code uses computational techniques similar to those of Harwell's HADES code for the study of point defects in bulk ionic crystals. Two sets of short‐range potentials are used to determine the energy and structure of the free (001) surface and of (001) CSL twist boundaries in MgO with values of Γ, the inverse density of CSL sites, ranging between Γ= 5 and Γ= 65. From comparison of the results obtained by means of the different potentials it is concluded that the Van der Waals attraction between oxygen ions on opposite sides of the interface is mainly responsible for the rather weak cohesion predicted for such bicrystals, whereas Coulombic interactions are found to play only a minor role. It then follows that (i) the (001) plane is not a favored plane for the formation of grain boundaries in pure oxides with NaCl structure and (ii) similarities should exist between (001) twist boundaries in ionic crystals with NaCl structure and in fee metals. These similarities are investigated by comparing calculated boundary structures and energy‐vs‐misfit angle curves for MgO with recent results for aluminum, copper, silver, and gold, in which a broad spectrum of different interatomic potentials was used. It is suggested that the rather strong cohesion of the pressure‐sintered MgO bicrystals of Sun and Balluffi may be due to impurities which have migrated to the boundary during sintering.
Antireflective Effects on a Soda‐Lime Glass Induced by Ar+ Implantation
Authors: GEOTTI‐BIANCHINI F. , POLATO P. , RUSSO S. LO , MAZZOLDI P.
Published: July 2010

The results of optical and chemical investigations on the anti‐reflective layers obtained by Ar+ implantation on a soda‐lime fiat glass are presented and discussed. The antireflective effect is ascribed to the appearance of an interferential layer with a perturbed refractive index and a lower Na content than the bulk glass and can be optimized by choosing a suitable range of implantation energies and doses. Sodium depth profiles were measured with the 23Na(p, α)20 Ne nuclear resonance reaction and the results compared with the information provided by the specular reflectance curves.
Physical Properties and Structure of Rf‐Sputtered Amorphous Films in the System Ti02‐Si02
Authors: HANADA T. , AIKAWA T. , SOGA N.
Published: July 2010

Amorphous films in the system Ti02‐Si02 were prepared by rf sputtering and their density, refractive index, and thermal expansion were measured. Also, the silicon Kα and titanium Kβ band emission spectra were obtained by X‐ray emission spectroscopy in order to determine the coordination state of silicon and titanium ions in these amorphous films. The density and refractive index increased, but not proportionally, with increasing Ti02 content. On the other hand, a minimum was observed in the thermal expansion coefficient at =15 mol% Ti02. The coordination state of silicon ions in the amorphous films did not change with Ti02 content. However, the coordination number of titanium ions changed from 4 to 6, depending on Ti02 content. These results indicate that, in amorphous films in the system Ti02‐Si02, the change of the coordination state of titanium ions has an important effect on physical properties, such as volume, molar refractivity, and thermal expansion.
Influence of Titanium Dioxide on the Sintering and Microstructural Evolution of Mullite
Authors: BAUDIN CARMEN , MOYA JOSE S.
Published: July 2010

Addition of TiO2 under the solubility limit enhances the initial sintering and grain size of mullite; amounts in excess of that limit inhibit sintering and drastically increase the total porosity and mean pore size.
Properties of Some Simple Glass/Ceramic Systems
Authors: HIGBY PAIGE L. , SHELBY JAMES E.
Published: July 2010

The density, transformation‐range behavior, and electrical conductivity of three glass‐crystal systems of increasing complexity were measured. The systems studied included glass/alumina composites, spherulitic lithium disilicate crystallized from glass of the same composition, and a commercial glass‐ceramic in which the crystallization of lithium metasilicate resulted in changes in the composition of the residual glass.
In Situ Whisker‐Reinforced AlPO4‐Modified β‐Eucryptite Glass‐Ceramic: I, Morphology and Crystallization Kinetics
Authors: Lee Kyoungho , Hirschfeld Deidre A. , Brown Jesse J.
Published: July 2010

A whisker‐reinforced glass‐ceramic composite in the Li2O‐Al2O3‐SiO2‐P2O5 system has been fabricated by a single‐stage process that simultaneously forms the glass‐ceramic material and whiskers of TiO2in situ. The method utilizes typical glass‐ceramic processing techniques and requires precise addition of a TiO2 nucleation agent during the glass‐melting operation, followed by controlled nucleation and crystallization. The maximum nucleation temperature, 740°C, was determined by differential thermal analysis (DTA), and the result was confirmed by scanning electron microscopy (SEM) of the microstructures formed by nucleation/isothermal crystallization heat treatments. The apparent activation energy for crystallization of the material was determined to be 285 ± 3 kj/mol. The average aspect ratio of the TiO2 whiskers depends on temperature and time during crystallization. The X‐ray diffraction patterns of the in situ composite show that eucryptite(ss) and rutile exist as two different phases; no additional phases were observed. Elemental X‐ray mapping by electron microprobe indicates that these highly crystallized composites consist of modified β‐eucryptite glass‐ceramic matrix and acicular grains of TiO2.
Microstructure of Strontium Titanate Thin Film Grown by the Hydrothermal‐Electrochemical Method
Authors: Kajiyoshi Koji , Hamaji Yukio , Tomono Kunisaburo , Kasanami Toru , Yoshimura Masahiro
Published: July 2010

Microstructures of SrTiO3 thin films grown on Ti substrates by the hydrothermal‐electrochemical method have been studied by transmission electron microscopy. The grown films consisted of a thin surface layer having an isotropic polycrystalline structure and a thick inner layer having a columnar structure. Pores of the order of several tens of nanometers were found at boundaries of columnar grains constituting the inner layer. A 20‐ or 30‐nm‐thick polycrystalline layer of Ti oxides contaminated with a small amount of Sr was also found at the SrTiO3 film/Ti substrate interface. During the film growth at this interface, the observed pores are considered to act as short‐circuit paths for mass transport from the film surface to the interface.
Modeling and Scaleup of Galvanic Deoxidation of Molten Metals Using Solid Electrolyte Cells
Authors: Yuan Shi , Pal Uday B. , Chou Kuo C.
Published: July 2010

Argon and induction stirred copper melts were deoxidized at different temperatures by short‐circuiting a solid electrolyte cell. The solid electrolyte cell consisted of an yttria‐stabilized zirconia tube closed at one end. The tube interior was flushed with a reducing gas and the tube was immersed in the copper melt. A layer of porous Ni‐ZrO2 cermet deposited on the inner wall of the tube served as the anode while the copper melt was the cathode. The deoxidation experiments were modeled as a function of mass transfer in the melt, temperature, electronic and ionic conductivity of the electrolyte, short‐circuit resistance, and flow rate of the reducing gas. The deoxidation model was used to discuss process optimization and scaleup.
Effect of Polarization Switch upon Stress in Thickness Vibration of a Ferroelectric Plate
Authors: Huo Yongzhong , Jiang Qing
Published: July 2010

The commonly encountered operational failure of ferroelectric actuators is the so‐called electric fatigue resulting from stress‐induced microcracks developed during polarization switch. This article presents a stress analysis for thickness vibration of a ferroelectric plate under cyclic electric loading programs with or without polarization switch. It concludes that polarization switch results in stresses of frequency close to the resonance, independent of the frequency of the applied electric field, and of a substantially large amplitude in comparison with stresses generated in the absence of polarization switch.
Chemical Vapor Deposition of YBa2Cu3Ox in a Cold Plasma Reactor sing an Aerosol Vaporization Technique
Authors: Chung Yong S. , Hill D. Norman , Carter W. Brent , Lackey W. Jack
Published: July 2010

A plasma‐enhanced chemical vapor deposition technique, utilizing an aerosol decomposition/vaporization process in a cold plasma reactor, was used to form YBa2Cu3O, (YBCO) thin films on single‐crystal MgO substrates. Aerosol droplets of the precursors were generated by an ultrasonic nebulizer operating at 1.63 MHz, while a 50 kW rf generator, operating at 2.87 MHz, was used to create the plasma and heat a stainless steel susceptor. Nitrate, acetylacetonate, and tetramethylheptanedionate compounds were used as precursors, and distilled water, ethyl alcohol, and an aqueous benzoic acid solution were investigated as solvents for the aerosol solution. The effects of the solubility and decomposition temperature of the chemical precursors, and the vapor pressure of the solvents, on the microstructure and phase assemblage of the deposits were determined. Specific combinations of substrate temperature, in the range of 800°‐940°C, and oxygen partial pressure, in the range of 0.3–2.7 kPa, were found to produce in situ, crystalline, stoichiometric YBCO films.
Isothermal Section of Ti‐B‐C Phase Diagram at 1600°C
Authors: Brodkin Dmitri , Barsoum Michel W.
Published: July 2010

The isothermal section of the Ti‐B‐C system at 1600°C for compositions in and adjacent to the TiB2‐TiCx‐Ti3B4compatibility triangle was revised to reflect the fact that Ti3B4 is an equilibrium phase in this system. Lattice parameter measurements together with image analyses of SEM micrographs of densifled compacts confirm that the end member of the TiB2‐TiCx.‐Ti3B4 compatibility triangle is TiC0.65 with an uncertainty in x of ±0.02.
Electronic Structures of Ln3+α‐SiAIONs with Correlations to Solubility and Solution Effects
Authors: Nakayasu Tetsuo , Yamada Tetsuo , Tanaka Isao , Adachi Hirohiko , Goto Seichi
Published: July 2010

First‐principles molecular‐orbital calculations using the discrete‐variational Xα method have been made on model clusters of α‐Si3N4 and its solid solutions with lanthanide elements, which occupy interstitial sites in the structure. The formula is LnχSi12–4.5χAl4.5χO1.5χN16–1.5χ (Ln = La, Nd, Gd, Dy, Ho, Er, Tm, Yb), i.e., a Ln‐α‐SiAION solid solution. Covalent bond strength between Si and N, evaluated by overlap population, increases because of the presence of trivalent charges at the interstitial sites. When a Ln3+ ion is present, antibondings occur between Ln orbitals and N/Si orbitals, and they depend significantly on the ionic radius of Ln3+. The total overlap population for the whole cluster is determined by the balance of Si‐N bond reinforcement and Ln‐N/Si antibonding. Although no lattice relaxation around the Ln3+ ion is included in the present calculation, good correlation between maximum solubility and the total overlap population for the whole cluster is demonstrated for the first time.
Yield Stress of Alumina‐Zirconia Suspensions
Authors: Ramakrishnan Vijay , Pradip  , Malghan Subhas G.
Published: July 2010

The yield stress of concentrated suspensions of alumina, zirconia, and mixed alumina‐zirconia powders was measured by the vane technique as a function of solids loading, relative amounts of alumina and zirconia, and pH. At the isoelectric point (IEP), the yield stress varied as the fourth power of the solids loading. The relative ratio of alumina and zirconia particles was important in determining the yield stress of the suspension at the IEP. The yield stress of single and mixed suspensions showed a marked variation with pH. The maximum value occurred at or near the IEP of the suspension. The effect of electrical double‐layer forces on the yield stress can be described on the basis of the Derjaguin‐Landau‐Verwey‐Overbeek (DLVO) theory. A normalized yield stress—that is, the ratio of the yield stress at a given pH to the yield stress at the IEP predicted by this model—showed good correlation with experimental data.
Transmission Electron Microscopy and Electron Energy‐Loss Spectroscopy Characterization of Glass Phase in Sol‐Gel‐Derived Mullite
Authors: Kleebe Hans‐Joachim , Hilz Gabriela , Ziegler Günter
Published: July 2010

Sol‐gel‐derived mullite ceramics were processed by pressureless sintering at 1600°, 1650°, and 1700°C for 4 h. Microstructural and microchemical characterization of the mullite materials was performed using transmission electron microscopy, in conjunction with energy‐dispersive X‐ray spectroscopy and electron energy‐loss spectroscopy (EELS). Apart from mullite grain diameter and triplepocket size, no major microstructural changes were observed with increasing sintering temperature. Residual glass was present at triple pockets and along two‐grain junctions. Not all grain boundaries revealed the presence of a continuous amorphous intergranular film. Clean interfaces were observed only at boundaries with one grain parallel to the [001] orientation (low‐energy configuration). Quantitative EELS analysis of mullite grains and glass pockets revealed only small changes in composition with increasing sintering temperature; i.e., the alumina:silica ratio slightly increased for mullite and glass. The analysis implied that mullite with this relatively high aluminum content would not be stable adjacent to residual glass. However, a stable glass‐mullite system has been proposed, because impurity cations were detected within glass pockets, which suggested a slight shift of the subsolidus line (glass‐mullite/ mullite) to a higher amount of alumina. Energy‐loss nearedge structure studies of the Si‐L2,3 edge revealed a similar near‐edge structure for the mullite, residual glass, and quartz. Thus, SiO4 tetrahedra were thought to be the main building units of the glass contained in sintered mullite.
Optimization of a Ductile‐Particle‐Toughened Ceramic
Authors: Sun Xudong , Yeomans Julie
Published: July 2010

The nature of the interfacial bond has a major effect on the degree of toughening that can be achieved in a ductile‐particle‐reinforced ceramic‐matrix composite. The effect of variation of oxygen partial pressure during fabrication on the bonding in an alumina‐nickel composite has been investigated. Calculations suggest that wetting of alumina by nickel should always be accompanied by spinel (NiAl2O4 formation. A range of microstructures within a single specimen have been produced, however, indicating that wetting occurs more rapidly than spinel formation and that reduction of oxygen partial pressure during the hot‐pressing process can prevent spinel formation after wetting has occurred. Within this specimen, interfaces that have been formed under nonwetting conditions or conditions under which spinel formation has occurred are weak, whereas wetting without spinel formation produces chemically strengthened and mechanically interlocked interfaces that lead to crack interaction with the metallic particles and a higher toughening increment than for other microstructures. Subsequent specimens fabricated from preconsolidation‐heat‐treated powder exhibit favorable microstructures throughout, are tougher, and show more‐desirable resistance‐curve behavior in double‐cantilever‐beam tests than specimens produced from unreacted powder.
Mixed‐Mode Fracture of Ceramics in Asymmetric Four‐Point Bending: Effect of Crack‐Face Grain Interlocking/Bridging
Authors: Li Ming , Sakai Mototsugu
Published: July 2010

The mixed‐mode fracture of a large‐grain‐size alumina ceramic and a soda‐lime glass is investigated. These ceramics are tested using straight‐through precracked or notched specimens. The straight‐through precrack is introduced by the single‐edge‐precracked beam method. Precracked or notched specimens are subjected to combined mode I/II or pure mode II fracture, under asymmetric four‐point bending, and pure mode I fracture, under symmetric four‐point bending. A pure mode II fracture is never achieved in the precracked polycrystalline alumina by the crack‐face friction inevitably induced by grain interlocking/bridging. The crack‐face friction in sliding mode reduces the local mode II stress intensity factor in the crack‐tip region and produces a sizable amount of mode I deformation. Accounting for the contribution of the crack‐face friction to the crack‐tip local stress intensity factors, KI and KII, in mixed‐mode fracture tests, the experimental results of the KI/KIc versus KII/KIc envelope and the initial angle of noncoplanar crack extension are in good agreement with the theoretical predictions of the maximum hoop‐stress theory.
AC‐Drive‐Enhanced Relaxor Characteristics and Domain Breakdown in Ferroelectrics Containing Quenched Impurities
Authors: Tan Qi , Viehland Dwight
Published: July 2010

The dielectric constant has been measured for various compositions in the (Pb1‐3/2yLay)(Zr0.65Ti0.35)O3 solution as a function of AC‐drive amplitude. These studies have shown the presence of strong nonlinearities and enhanced relaxor characteristics with increasing AC drive. Corresponding transmission electron microscopy investigations demonstrated an enhanced breakdown of ferroelectric domains. Polarization studies revealed linearity in the range of field strengths investigated, demonstrating that the dielectric nonlinearities are not due to intrinsic polarization switching, but rather to the dynamics of various domainlike states. In the disordered condition, evidence is then presented which demonstrates a mesoscale freeze‐out of polar clusters.
Preparation and Mechanical Properties of SiC Whisker and Nanosized Mullite Particulate Reinforced TZP Composites
Authors: Zhang Zongtao , Huang Yung , Zheng Longlie , Jiang Zuozhao
Published: July 2010

The influence of the addition of nanometer mullite particulates and SiC whiskers coated with alumina on the mechanical properties of tetragonal zirconia polycrystals (TZP) was studied. With increasing mullite(p) content the high‐temperature flexural strength increased, and a maximum value of 360 MPa at 1000°C was reached at 15 vol% mullite(p. Furthermore, 10 vol% SiC(w) reinforced 15 vol% mullite/TZP composites improved the high‐temperature strength up to 490 MPa at 1000°C, 2.7 times that of pure TZP matrix. This high‐temperature strengthening is attributed to load transfer from TZP matrix to SiC(w) and mullite particulates. Significant whisker pull‐out and interface debonding were also observed on the fractured surfaces when SiC(w) was coated with Al2O3 film.
Alternative Route for Synthesis of Barium Titanyl Oxalate: Molecular Precursor for Macrocrystalline Barium Titanate Powders
Authors: Potdar Hari S. , Deshpande Subhash B. , Date Sadgopal K.
Published: July 2010

An important molecular precursor to barium titanate, namely, barium titanyl oxalate [BaTiO(C2O4)2.4H2O], has been synthesized by an alternative route. An alcoholic solution containing 1 mol of butyl titanate monomer [(C4H9O)4Ti] is reacted with alcoholic solution containing 2 mol of oxalic acid (H2C2O4:2H2O) to form an intermediate soluble oxalotitanic acid [H2TiO(C2O4)2.nH2O]. The oxalotitanic acid in alcoholic medium is subjected to cation exchange reaction with aqueous solution containing equimolar barium acetate to form an insoluble barium titanyl oxalate (BTO) in yields of 80–85% at room temperature. The pyrolysis of BTO in air at T.750°C/5 h produced barium titanate (BT) powders.
Use of Ferroelectric Hysteresis Parameters for Evaluation of Niobium Effects in Lead Zirconate Titanate Thin Films
Authors: Klissurska Radosveta D. , Tagantsev Alexander K. , Brooks Keith G. , Setter Nava
Published: July 2010

The effects of niobium doping on the hysteresis parameters of sol—gel Pb1.1−(x/2)(Zr0.53Ti0.47)1−xNbxO3(0, x, 0.05) have been reported for two sets of films with analogous grain size and degree of (111) texture but with different surface microstructures. For both sets, a strong continuous decay of the remnant and maximum polarizations and slope of the hysteresis loop at the coercive field was observed with increasing niobium concentration. The field dependence of the remnant polarization for any given niobium‐doped film was identical to the functional field dependence of the undoped reference film, if multiplied by a niobium‐concentration‐dependent constant. Although the maximum and remnant polarizations decayed as the dopant level increased, their difference remained the same value as that of the undoped film at any given field. The width of the loop (at zero polarization) was insensitive to the niobium concentration at any given field. A linear increase in coercive field asymmetry (up to 40 kV/cm) was observed with niobium addition, yet was field independent and, thus, electrostatic in origin. Niobium governed switching through a reduction of the number of switching domains, without changing the total lattice polarization response. Microstructure‐related effects on switching, such as decreased volume fraction of ferroelectric material or field‐screening effects due to the presence of a pyrochlore second phase, were eliminated as the origin of the hysteresis changes. This paper has demonstrated how hysteresis features and their field dependencies can be used to separate the effects of niobium‐induced microstructural changes from niobium lattice doping influences on the hysteresis loops.
Influence of Cu2O and CuAlO2 Interphases on Crack Propagation at Cu/α‐Al2O3 Interfaces
Authors: Reimanis Ivar E. , Trumble Kevin P. , Rogers Kirk A. , Dalgleish Brian James
Published: July 2010

In‐situ crack‐propagation experiments, in conjunction with thermochemical experiments, have been used to examine the role of discontinuous interphases on the fracture behavior of solid‐state diffusion‐bonded Cu/α‐Al2O3 couples. Clean, interphase‐free interfaces exhibit crack extension by brittle decohesion at the crack tip at an initiation fracture energy of 125 J/m2. Crack propagation is characterized by an increase in the fracture energy with increases in the crack length (R‐curve behavior). When interfacial chemical reaction products are present, the crack growth is altered, depending on the characteristics of the interphase. The presence of Cu2O needles results in preferential debonding along the Cu2O/Al2O3 interface. On the other hand, finer CuAlo2 needles visibly impede crack propagation and result in a higher interface initiation fracture energy (}190 J/m2) than that of the interphase‐free interface. The effects of the Cu2O and CuAlo2 phases on the fracture energy are discussed.
Synthesis of Calcium Silicate Hydrate with Ca/Si = 2 by Mechanochemical Treatment
Authors: Sasaki Kaori , Masuda Tsuguya , Ishida Hideki , Mitsuda Takeshi
Published: July 2010

An amorphous, C‐S‐H‐like phase with Ca/Si = 2 was synthesized from amorphous precipitated silica, calcium oxide, and water by mechanochemical treatment using a vibration mill at room temperature. The product was studied by XRD, 29Si MASNMR, TEM, analytical TEM, and TGA‐DTA. After 14 h of treatment, the starting materials react to form an amorphous phase (C‐S‐H‐like phase). The XRD pattern of C‐S‐H‐like phase resembles the C‐S‐H formed hydrothermally or by cement hydration except it has no reflection at 0.182 nm. The 29Si NMR results revealed a silicate anion structure of C‐S‐H‐like phase consisting mainly of a mixture of a monomer and a dimer. On heating, the C‐S‐H‐like phase decomposed into β‐dicalcium silicate below 1000°C.
Compositional Studies of Lanthanum‐Modified Morphotropic Phase Boundary Pb(Mg1/3Nb2/3)O3—PbTiO3 Ceramics
Authors: Gupta Surya M. , Viehland Dwight
Published: July 2010

Investigations have been performed on the La‐modified (1 ‐ x)Pb(Mg1/3Nb2/3)O3—(x)PbTiO3 crystalline solution for compositions close to the morphotropic phase boundary (MPB) using energy‐dispersive X‐ray spectrometry (EDS). Studies were performed on specimens with La contents between 0 and 10 at.% for x= 0.35 which were fabricated by keeping the average Mg/Nb/Ti ratio in the bulk ceramic unchanged. In this series of samples, La3 was compensated for by introducing B‐site vacancies. Quantitative analysis by EDS revealed a change in the B‐site cation concentrations with La substitution. It was observed that the Nb concentration decreases and the Ti concentration increases with increasing La content, indicating that local charge compensation in the perovskite phase is taking place by an adjustment in B‐site cation concentrations. Phase analysis demonstrated the presence of a second phase for La contents above 2 at.%. Scanning electron microscopy then revealed the presence of a secondary pyrochlore phase with an octahedral‐like morphology. The composition of the pyrochlore phase was found to be rich in Nb and poor in Ti. The effects of changes in composition on dielectric properties, polarization, and electrically induced strain were then investigated.
Thermodynamic Assessment of the Strontium–Copper–Oxygen System
Authors: Risold Daniel , Hallstedt Bengt , Gauckler Ludwig J.
Published: July 2010

The phase diagram and thermodynamic data on the Sr–Cu–O system at a total pressure of 105 Pa (1 bar) have been reviewed and assessed. Gibbs energy functions for the ternary oxides Sr2CuO3, SrCuO2, Sr14Cu24O41, SrCu2O2, and the liquid phase have been optimized, and a consistent thermodynamic description is presented. Calculated SrOCuOx phase diagrams in air and in 1.01 ×105 Pa (1.01 bar) O2, the oxygen potential diagram, and various thermodynamic properties are shown and compared to experimental data.
Thermodynamic Modeling and Calculation of Phase Equilibria in the Strontium–Calcium–CopperOxygen System at Ambient Pressure
Authors: Risold Daniel , Hallstedt Bengt , Gauckler Ludwig J.
Published: July 2010

The phase‐diagram and thermodynamic data on the Sr–Ca–CuO system at a total pressure of 105 Pa (1 bar) are reviewed and assessed. Gibbs energy functions for the (Sr,Ca) solid solutions and the liquid are optimized, and a consistent thermodynamic description is presented. Calculated phase relations are shown in various isothermal and isoplethal sections and compared to experimental data. Special attention is given to the stability of the infinite‐layer compound, as a function of temperature and oxygen partial pressure.
Grain‐Boundary Sliding in Fluorine‐Doped Silicon Nitride
Authors: Pezzotti Giuseppe , Ota Kenichi
Published: July 2010

A systematic study of the effect of small additions of fluorine impurity on the relaxation and creep behavior of Si3N4 ceramics was conducted. A model polycrystal, consisting of equiaxed grains and containing only pure (glassy) SiO2 at the grain boundary, was selected for this investigation. The boundary SiO2‐glass film, completely surrounding the grains, was doped with increased amounts of the glass‐network modifier fluorine to systematically lower its bulk viscosity. The addition of the fluorine made both the grain‐boundary relaxation peak and the background of internal friction notably shift toward lower temperatures; the scaling was in accordance with the lowered viscosity of the bulk fluorine‐doped SiO2 glass. Invoking basic viscoelasticity principles, the grain‐boundary relaxation phenomenon could be rationalized and the internal friction data consistently related to the macroscopic (torsional) creep behavior of the polycrystal.
The α–β Transformation in Silicon Nitride Single Crystals
Authors: Suematsu Hisayuki , Mitomo Mamoru , Mitchell Terence E. , Petrovic John J. , Fukunaga Osamu , Ohashi Naoki
Published: July 2010

Single crystals of α‐Si3N4 were annealed at 2000°–2150°C. The β phase was detected after annealing at 2150°C only when the crystals were surrounded by MgO·3Al2O3 or Y2O3 powders. On the other hand, no evidence of the α–β transformation was found when the crystals were annealed without additives. The solution–precipitation mechanism was concluded to be the dominant factor in the α–β transformation of Si3N4.