bluuebunny/crossref_metadata_2025 huggingface dataset:
On the influence of impurity additions and quenching temperature on the course of the microhardness (HV) during a two‐step ageing treatment of an Al‐2.0 at.%Zn‐1.3 at.%Mg Alloy
Authors: Gerlach R. , Löffler H.
Published: January 2007

A pure as well as the analogous technical alloy were directly quenched from Tq = 400 °C or 490 °C to Ta, preaged at Ta (ranging between 50 °C and 160 °C) various times (ta), and subsequently postaged at R.T. up to tpost = 42 d.

— Ageing the samples below the upper limit temperature of the homogeneous formation of G.P. zones (Thn) no essential difference in the course of the HV‐number attained after one‐ as well as two‐step ageing in dependence on the addition of impurity atoms and Tq could be found.

— Contrary to this behaviour after pre‐ageing at Ta > Thn and postageing at R.T. a variation of both Tq and the content of impurity atoms shows a considerable effect. The reason is the difference in the density of nucleation sites for heterogeneous formation of precipitates of the η′‐ and/or η‐phase in dependence of Tq and impurity content.
”︁Four‐fold„ refringence in quartz
Authors: Semenchenko † V. K. , Bodnar I. T. , Isupov V. A.
Published: January 2007

An attempt is made to interprete the simultaneous existence of four refractive indexes (two ordinary and two extraordinary) near the α—β phase transition in quartz from the optical point of view. The theory of thermodynamical stability predicts the appearance of fluctuation areas of the α‐ and β‐phases in the vicinity of the α—β transition. On the basis of this theory the formation of infinite clusters, consisting of the merged fluctuation ranges, is assumed.
Crystal destruction of zeolite NaA during ion exchange with magnesium and calcium ions
Authors: Lutz W. , Fahlke B. , Lohse U. , Bülow M. , Richter‐Mendau J.
Published: January 2007

Extreme conditions of ion exchange like, for instance, highly concentrated solution, high temperature and a long time of exchange can cause destructions of crystals. Zeolites NaMgA are structurally degraded much more than zeolites NaCaA. Reason for the reduced stability of crystals in presence of alkaline earth ions is the proton concentration increased beyond the dissociation equilibrium of water owing to the formation of weakly dissociated alkaline earth ion hydroxides. The zeolite lattice is destroyed hydrolytically by the influence of protons.
Studies on induced smectic phases (III). Fourier transform infrared and laser‐raman spectral differences between isotropic and induced smectic phase of binary mixtures of nematogens with contrasting dielectric anisotropies
Authors: Szabon J. , Pilz W. , Koswig H. D.
Published: January 2007

The SE, SB, SA induced phase sequence was detected in binary mixtures of two nematogens, 4,4′‐di‐n‐heptyl azobenzene (7AB) with 4‐n‐pentyl‐4′‐cyano biphenyl (5CB). The mixtures as well as the single components were studied by Fourier transform IR and laser‐Raman spectroscopy at different temperatures. Charge redistribution of 5CB is demonstrated by the spectral differences found by the ratio‐recorded IR spectra and also by integrating the intensities of some Raman lines. The spectra of the different phases of the 7AB—5CB mixture, built up from components of different length, indicate a population increase of the gauche conformers of 7AB in the smectic A phase.
The precipitation of alkaline‐earth metal polymetaphosphate hydrate powders from aqueous solution. Nucleation and crystal growth processes, final precipitate compositions and crystal sizes
Authors: Packter A. , Doherty W. O. S.
Published: January 2007

The precipitation of barium, strontium, calcium and magnesium polymetaphosphate hydrates was studied from aqueous solutions of initial metal salt concentrations from 0.001 to 3 M at 20 °C; equivalent sodium polymetaphosphate solutions were added to the alkaline‐earth metal chloride solutions. Precipitate compositions were determined by chemical analysis, paper chromatography, potentiometric analysis, thermogravimetric and differential thermal analysis and infra‐red spectrophotometry; final crystallite morphologies and sizes were studied by scanning electron microscopy and X‐ray powder diffraction.

Nucleation rates and nucleus numbers (at the end of the induction periods) were very high; crystal numbers varied from 1014 to 1015 at the critical concentrations to above 1017 per 1. solution.

Crystal growth rates were also very high and varied as the fourth power of the initial metal salt concentration. High molecular‐weight metal polymetaphosphate hydrates were precipitated from the more dilute solutions (0.001 to 0.025 M) while increasing amounts of the more soluble intermediate and low molecular‐weight products were precipitated from the more concentrated solutions. Washing with cold water removed the tri‐ and tetralinear and cyclic phosphate products. The magnesium salts were not precipitated even from 3 M aqueous solutions.

The precipitates from aqueous (NaPO3(I))n (n = 12) solutions had the compositions (BaP2O6 · 2.5 H2O)6, (SrP2O6 · 3 H2O)n and (CaP2O6 · 4 H2O)n while the magnesium salt precipitate from 20 percent aqueous acetone solution had the composition (MgP2O6 · 4 H2O)n, the precipitate n values varied from 19 to 13. The precipitates from aqueous (NaPO3(II))n (n = 20) solutions contained 0.5n to n additional adsorbed water molecules; these precipitate n values varied in turn from 40 to 26.

The final precipitate powders consisted of ‘spherules’ of highly microcrystalline or amorphous polymer glass; the spherule diameters were about 0.2 μm at the critical concentrations and decreased to below 0.05 μm with increasing solution concentrations.
Structural phase transitions in the LaMnO3+λ system
Authors: Bogush A. K. , Pavlov V. I. , Balyko L. V.
Published: January 2007

Structural phase transitions in the LaMnO3+λ system are studied at various temperatures and with different Mn4+ ion concentrations. Two structural phase transitions are established. The O′‐orthorhombic – O‐orthorhombic transition (O′O transition) is due to removing the cooperative Jahn‐Teller distortions and occurs in the Mn4+ concentration range from 10 to 14% at room temperature. The temperature of this transition varies from 710 K for the stoichiometric LaMnO3 to room temperature for LaMnO3.07. The O‐orthorhombic – rhombohedral transition (OR transition) is due to the change of the rotation axis of the undistorted MnO6 octahedra from [100] and [110] to [111]. The temperature of this transition varies from 1010 K for LaMnO3 to 230 K for LaMnO3.135. The structural phase diagram of temperature vs composition is plotted, indicating the existence of regions of the phase with different structures.
Crack temperature rise due to crack propagation in visco‐plastic materials
Authors: Michel B. , Gründemann H.
Published: January 2007

An attempt is made to simulate the temperature field connected with a propagating crack in a visco‐plastic material. The authors apply modern continuum thermodynamics of strain‐rate sensitive work‐hardening materials to describe heat dissipation, convection, and conduction phenomena connected with the temperature development in the near‐crack region. The powerful finite element technique has been used to solve the coupled thermomechanical system of field equations being highly non‐linear. The results are in a better agreement with experiments than those obtained by the classic uncoupled methods.
Temperature dependence of the tetragonal distortion in I–III–VI2 compounds
Authors: Neumann H.
Published: January 2007

On the basis of free energy considerations with anharmonic contributions included a model is developed for the temperature dependence of the tetragonal distortion Δ of the I–III–VI2 compounds. Agreement with experimental data can be only achieved if compounds with Δ < 0.05 and Δ > 0.05 are considered separately. It is suggested that this result is related to the structural order‐disorder behaviour of the I–III–VI2 compounds.
Thermoluminescence studies in KBrxI1–x mixed crystals
Authors: Veeresham P. , Rao U. V. Subba , Babu V. Hari
Published: January 2007

Thermoluminescence (TL) studies have been carried out in KBr, KI, and in different compositions of KBrxI1–x mixed crystals as a function of X‐irradiation time. The TL glow peaks have been analysed and the trap depths and frequency factors have been calculated for different compositions. The complex TL peaks observed in these crystals were isolated by using thermal cleaning technique. The various glow peaks observed in these crystals were attributed to native impurities, first stage and second stage colour centers and the results have been discussed.
Industrial purification of caprolactam by means of crystallization from aqueous solution
Authors: Synowiec J. , Synowiec P.
Published: January 2007

A course of investigations and the adopted method of caprolactam crystallization process on industrial scale have been discussed. The product characteristics as well as economic indices of the process were mentioned. The presented method gives new possibilities in technology of the product purification.
Metallurgically grown Schottky junction in directionally solidified eutectic Ag–Si alloys
Authors: Arnold Michael , Frühauf Joachim , Schneider Helmut Günther
Published: January 2007

Metallurgically grown M(metal)–S(semiconductor) phase boundaries in directionally solidified AgSi alloys were investigated relative to their behaviour as Schottky junctions. By the aid of point contacts I/V characteristics have been measured which correspond to these ones of Schottky diodes. The Si crystallites were proved to be n‐doped. Reverse breakdown voltages of 8 … 24 V are not incompatible with the purity of the used materials. In forward direction the value of diode factor n = 1.1 … 5 shows the existence of several current flow mechanisms. In order to be able to interpret the characteristics it is necessary to have exact information on the specific resistivity of the Si crystallites and on the content of grain boundaries and dislocations in silicon. Beyond that the complicated shape of Si crystallites prevents the necessary determination of the interface size.
AlxGa1–xAs/GaAs thin window concentrator solar cells by LPE plus vapour phase diffusion
Authors: Romero R. , Sulima O. V.
Published: January 2007

Zinc diffusion from the vapour phase on a previously grown LPE nAlxGa1–xAs/nGaAs sample is discussed for thin window concentrator solar cell manufacture. A high cell shunt resistance and a low series resistance are achieved together with improved optical parameters via an impressed electric field in the emitter. Dark current components are rather low and 21.8% conversion efficiency is measured at AM 1.3. When the photogenerated short circuit current density is 8 A · cm−2, the fill factor is 0.77 and open circuit voltage is 1140 mv.
Preparation and characterization of strontium formate dihydrate
Authors: Prieto A. C. , Gonzalez A. , Hernandez E. , Rull F. , de Saja J. A.
Published: January 2007

Large single crystals of strontium formate dihidrate of high opticalquality have been grown from aqueous solutions by slow cooling from 50 °C to 20 °C. A thermogravimetric study is carried out in order to study the kinetic parameters and associated mechanism of the dehydration process. Raman vibrational assignments and a qualitative description of the normal modes are proposed. Two non‐equivalent formate and water arrangements with different degrees of vibrational distortion are established.
Growth and dissolution of BaFCl crystals
Authors: Somaiah K.
Published: January 2007

Single crystals of BaFCl have been growth by flux technique using BaF2 and BaCl2. Etching with formic acid revealed dislocation etch pits on (001) cleavage faces of the crystals, at room temperature. The influence of etching parameters such as undersaturation, temperature and concentration of poison in the etchant is studied. Decreasing the undersaturation of formic acid by reducing the percentage of water and increasing the temperature of the etchant were found not to have any effect on the morphology of etch pits. However, as the CdCl2 poison concentration is gradually increased, the orientation of the pits change from 〈100〉 to 〈110〉 at high concentration.
Growth and selective etching studies on NaBrO3 crystals
Authors: Rao K. Kishan , Sirdeshmukh D. B.
Published: January 2007

Surface studies on (111) faces of sodium bromate crystals grown from aqueous solution show the presence of growth steps. A new etchant consisting of a mixture of 8 parts of glacial acetic acid and 2 parts of formic acid, to which 3 mg/cc of cupric nitrate is added, reveals the dislocation sites on (111) faces of these crystals. The etching action on (111) and (111) faces is different. Different microhardness values are recorded on (111) and (111) faces of these crystals. The difference in etching action as well as in microhardness values on (111) and (111) faces is discussed.
Mechanical behaviour of magnesium oxide single crystals at temperatures from 196 to 2400 °C
Authors: Berezhkova G. V. , Perstnev P. P. , Turaeva N. R. , Batrakov N. A.
Published: January 2007

The stress — strain characteristics of MgO single crystals in compression are investigated in the temperature range from –196 °C to 2400 °C on samples of the same shape and size. It is shown that the stress — strain curves may be subdivided into three basic types, each of them corresponding to the definite temperature range. The work hardening rate at stage I is temperature independent and at stage II lineary decreases with temperature increase in overall temperature range where work hardening is observed. The high temperature maximum in the temperature dependence on the proportional limit is found which is not due to the effects of impurities. The effect of geometrical form of specimens on stress‐strain parameters and the local true strain distribution in compressed specimens have been studied.
Dendritic structures in gel grown Gypsum
Authors: Raju K. S.
Published: January 2007

Sparingly water soluble Calcium Sulphate dihydrate (Gypsum) single crystals are grown by gel method, derived from the highly soluble reactants, Calcium Chloride and ammonium sulphate. By the diffusion of 1M Calcium Chloride solution into Sodium metasilicate gel (Sp.gr: 1.06 gm Cm–3, pH ∼ 7.5), imbedded before setting, with varied amounts of weak acid (acetic acid) and 20 ml of 1M ammonium sulphate solution, dendritic structures are commonly observed in the gel at the interface, at a particular concentration of the acid. The needle shaped tabular crystals are also observed to grow at the greater depths in the gel.

Dendrites are studied by optical, X‐ray diffraction and Infra‐red studies. It has been established that the dendrites are Calcium Sulphate dihydrate crystals formed probably due to the influence of soluble impurities (like calcium acetate, in the present case), when the rate of diffusion is fairly high and the twinning mechanism favoured. The implications are discussed.
Investigations on the HCl gas‐phase etching of differently doped and oriented gaas crystals
Authors: Dorshchand S. , Däweritz L. , Berger H.
Published: January 2007

The influence of the orientation and dopant on the dissolution of GaAs surfaces in H2–HCl gas mixtures has been investigated. For this purpose the etch rates, temperature regions of different etching behaviour and the corresponding activation energies were determined for temperatures ranging from 540 °C to 945 °C. The etch rate anisotropy is correlated with the three existing temperature regions of different dissolution mechanisms. The orientation‐dependent transition temperatures are influenced by the dopant and can be related to the thermodynamic data of the dopant.
Analysis of stress distribution in semiconductor substrates with film edges
Authors: Fischer A.
Published: January 2007

Assuming a relaxing film stress in the edge region and a resulting superposition of partial surface stresses, the respective stress distribution in the crystal is calculated. For practical estimates of the stress values an approximate solution is given. The results are discussed with respect to the generation of defects at film edges.
Radiation hardening studies in KBr‐KI mixed crystals
Authors: Rao U. V. Subba , Veeresham P. , Babu V. Hari
Published: January 2007

Radiation hardening studies have been made in KBr, KI and in different compositions of KBr‐KI mixed crystals, grown from melt by Kyropoulos technique. The irradiation hardness in mixed crystals is found to vary non‐linearly with composition, attaining a minimum value at intermediate compositions. Dislocation density measurements have shown a high concentration of dislocations and grain boundaries in mixed crystals as compared to end crystals. The results obtained on radiation hardening of mixed crystals were explained in terms of dislocations present in them.
Thermoluminescence and optical absorption studies of KBr crystals doped with ca2+
Authors: Veeresham P. , Reddy K. Narasimha , Rao U. V. Subba , Babu V. Hari
Published: January 2007

Thermoluminescence studies of KBr crystals doped with 0.5 mole % of Ca2+ both in the ‘as‐grown’ state and after quenching them from various elevated temperatures indicate that the position of the glow peak which has been assigned to F‐centers is found to depend upon the state of dispersion of impurity. Bleaching of the X‐irradiated samples result in an additional peak and this has been attributed to Z1‐centers. Optical absorption measurements also confirm the formation of Z1‐centers in Ca2+ doped KBr crystals.
Effect of change of state of aggregation of impurity on tl and microhardness of KClxBr1–x mixed crystals doped with Ca2+
Authors: Rao U. V. Subba , Veeresham P. , Reddy K. Narasimha , Babu V. Hari
Published: January 2007

Microhardness and Thermoluminescence (TL) measurements have been made in KClxBr1–x mixed crystals doped with Ca2+ impurity. The variation of hardness in undoped and Ca2+ doped KClxBr1–x crystals with quenching temperature is investigated. TL studied of KClxBr1–x crystals doped with Ca2+, both in as‐grown state and after quenching them from various elevated temperatures indicate that the positions of the glow peak which has been attributed to F‐centers is found to depend upon the state of dispersion of impurity.
Doping process control in silicon epitaxy (II). Calculation of optimum control
Authors: Valkó P. , Kósza G. , Richter F.
Published: January 2007

A procedure is developed to obtain desired dopant profile in epitaxial layer growth. Based an the results of system identification, linear‐quadratic optimal control theory is used to determine the optimal input PH3 concentration as a function of time. In the performance index an auxiliary weighting coefficient must be incorporated. It is discussed how to select this weighting coefficient.
Effect of oxygen impurities on recombination luminiscence in some alkali halide crystals
Authors: Cywińaski R. , Damm J. Z.
Published: January 2007

The low‐energy emission spectra of nominally pure NaCl, KCl, KBr, and KI crystals are examined at different electron beam densities and at temperatures between 80 and 300 K. The results obtained for the crystals of the same chemical formula but with different OH− contents, or subjected to the action of the air atmosphere, show that the emission bands considered are related with the presence of oxygen ions formed during radiolysis of such impurities like OH− or H2O. The decay of pertinent emission observed at higher radiation doses is explained by the transformation of simple oxygen ions into the neutral, inactive O2‐molecules.
Structure and properties of ANOF Layers
Authors: Dittrich K.‐H. , Krysmann W. , Kurze P. , Schneider H. G.
Published: January 2007

Oxide layers produced by ANOF technique show other structures and properties than such ones anodized as usual. Some characteristic mechanical, electrical and chemical properties are described. Their dependence on structure is discussed.
Crystal growth of potassium bichromate at the boiling point
Authors: Sokolowski W. , Wojciechowski K. , Sangwal K. , Rodriguez‐Clemente R.
Published: January 2007

The results of an investigation of the growth of potassium bichromate crystals at the boiling point, and their habit and surface micromorphology are reported.
Low temperature TL glow curves in KBrxI1‐x mixed crystals
Authors: Veeresham P. , Subba Rao U. V. , Hari Babu V.
Published: January 2007

Thermoluminescence (TL) glow curves were recorded in KBr, KI and in different compositions of KBrxI1‐x mixed crystals at LNT. For this a cryostat has been designed and fabricated. The glow peaks observed in these crystals have been attributed to differnent colour centers.
Low‐temperature anomalies in the plastic response of crystalline materials
Authors: Feltham P. , Butt M. Z.
Published: January 2007

The non‐uniform, wavy, temperature‐dependence of the yield‐stress and of the rate of logarithmic creep frequently observed in metals, alloys and non‐metallic crystalline solids at low temperature, is shown to be largely a consequence of the progressive inhibition of dynamic recovery processes as T → 0 K. Plastic deformation becomes increasingly localised, resulting in high stress‐concentrations. On allowing for this increase in the usual equations of the deformation kineties, the anomalies are very well accounted for.
Concentration dependence of the critical resolved shear stress of Cd‐Zn single crystals in the temperature interval 1.5 K—50 K
Authors: Navrátil V. , Hamerský M.
Published: January 2007

Cd—Zn single crystals were deformed in creep at temperatures between 1.5 K and 50 K. The from the creep experiments established critical resolved shear stress (CRSS) increases with cn where c is the atomic concentration of zinc as solute. The exponent n was found to be close to 2/3, i.e. the concentration dependence of the CRSS can be explained according to the theory of LABUSCH.
A new Iodide method for the preparation of II‐VI and IV‐VI compounds
Authors: Karagiozov L. , Trifonova E. P.
Published: January 2007

A low‐temperature method for II‐VI and IV‐VI chalcogenides is proposed, based on the reaction of the iodide of group IIB or IVA element with the element of group VIA, in a flow reactor. The dependence of the electrical parameters of PbTe on technology conditions is investigated.
Study of the vibrational spectra of Natural Skolecite
Authors: Pechar F.
Published: January 2007

The vibrational spectra of the natural zeolite skolecite (locality Teigarhorn, Island) were measured in the infrared (200–4000 cm−1) and the far‐infrared (40–400 cm−1) regions; the infrared reflectance (200–1400 cm−1) and Raman scattering (50–4000 cm−1) spectra of the polycrystalline material were also measured. The KKK‐1 program (KROUPA, PELZELT) was used to calculate the dispersion curves of the optical constants. The bands in the spectra can be assigned to the vibrations of the individual bonds and structural groups of the skolecite on the basis of the literature data.
Peculiarities of X‐ray diffraction in quartz monocrystals
Authors: Bezirganyan P. H. , Zargaryan Y. G. , Aslanian V. G.
Published: January 2007

The scattering of X‐rays in quartz monocrystals has been investigated. It has been shown, that, even in thick quartz monocrystals, kinematic scattering takes place and pendular bands appear. It has been demonstrated experimentally that only a diffraction pattern of clearance is obtained in bicrystal quartz interferometers, whereas in tricrystal interferometers moiré patterns are not produced. The beam reflected from one part of the crystal is no longer reflected from the other parts of the same crystal.
Dislocations in CdTe
Authors: Nagabhooshanam M. , Hari Babu V.
Published: January 2007

Two different etchants were developed to get boat‐ and triangular type etch pits on CdTe crystals. The subboundaries are shown to be symmetrical tilt boundaries. Dislocation density and microhardness measurements were made on three CdTe crystals grown by Bridgman, Travelling heater and vapour phase technique and were correlated.
Plasticity of high purity iron single crystals (II) surface observations
Authors: Novák V. , Šesták B. , Zárubová N.
Published: January 2007

Slip traces were studied on high purity iron single crystals after deformation in tension in the temperature range from 4.2 to 473 K (the same crystals were used for the work‐hardening study described in Part I of this paper). By evaluation of Nomarski interference contrast and by method of repolishing of the surface before incremental loading detailed quantitative information was obtained about slip line pattern in various work‐hardening stages. An improved model of slip processes in stage III of the work‐hardening curve is presented.
Electrons, dislocations, and low‐temperature plastic deformation
Authors: Galligan J. M.
Published: January 2007

The influence of electron drag processes on the plasticity of normal state metals is demonstrated in the case of zinc crystals. These results show that dislocations move as underdamped oscillators at low temperature and that dislocations flutters as they move. This flutter motion, in contrast to kink motion which is expected to have no long range stress, is the dominant drag process at temperatures below ≈ 4.2 K.
Sub‐boundaries on (002) cleavages of Li2CO3 single crystals
Authors: Raju K. S. , Palaniswamy M. , Ramasamy P. , Laddha G. S.
Published: January 2007

Linear arrays of dislocations (straight, terminating and curved) are observed on etching with 2% citric acid (002) cleavages of lithium carbonate (Li2CO3) single crystals, grown by zone melting technique. As the dislocations are non‐uniformly spaced and disappear on successive etching, they may not be revealing low‐angle grain boundary, nor slip traces as they are terminating and curved meaning crystallographically non‐oriented. On the observation of experiments on successive etching and etching of matched pairs, it is concluded that the arrays of etch pits reveal dislocation walls (dislocation density 1.1 × 106 — 1.5 × 107 pits cm−2) probably created due to the localized thermal stresses released as a result of high temperature annealing of the crystal during growth. The implications are discussed.
Metallographic and electron microscopical analysis of microdefects in Fz‐silicon crystals
Authors: Hoffmann K. , Pasemann M. , Sevcik S.
Published: January 2007

In dislocation‐free floating‐zone silicon crystals two types of microdefects were observed and analyzed by means of optical and electron‐microscopical methods. Microdefects of type I occur in swirl‐type arrangements throughout the whole wafer and appear as etch hillocks below which one can find second phase particles. Due to the chemical‐mechanical polishing near the wafer surface microdefects of type II are generated which also occur in spiral arrangements. These defects could be identified to be plate‐like vacancy agglomerates on {111} planes.
Chemical and microscopical investigations on Ti‐ and Mg‐doped LiNbO3 single crystals
Authors: Malicskó L. , Cravero I. , Krajewski Th.
Published: January 2007

In lithium niobate single crystals grown by the Czochralski‐technique from Mg‐ and Ti‐doped melts the concentration distributions of the dopants and the microinhomogeneities were investigated using chemical analysis, optical microscopy and scanning electron microscopy in connection with (energy dispersive) X‐ray microanalysis. It was found that Mg dopants, if present in the melt simultaneously with Ti, increase the effective distribution coefficient of the titanium dopants. This results in a higher quality of the crystals because of a probably improved stability of the crystallization front.
A curved‐crystal spectrometer for soft X‐ray emission studies of metals and metallic alloys
Authors: Zschech E. , Wehner B. , Kleinstück K. , Blau W. , Dick M. , Förster E.
Published: January 2007

Quantitative comparisons between obtained X‐ray emission spectra of 3d‐transition metal elements and their alloys as well as band structure calculations demand an energetic resolution of the order of E ≈ 1 eV. A highly resolving focussing X‐ray spectrometer is described which allows very high quality X‐ray emission spectra to be obtained. The spectrometer utilizes a spherically bent Si(111)‐crystal operated on the Rowland circle. The selection, fabrication and testing of the crystal are described. A comparison between own measurements of line‐width of Co‐Kα1,2‐ and Cu‐Kα1,2‐emission lines as well as literature values is given. The required energetic resolution can be obtained in the upper range of the Bragg angle δ with the described X‐ray spectrometer and a spherically bent crystal.
Variation of low temperature internal friction at microplastic deformation of high purity molybdenum single crystals
Authors: Pal‐Val P. P. , Kaufmann H.‐J.
Published: January 2007

Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle‐ or dislocation oscillations, respectively, dislocation‐point defect interactions as well as defect generation at microplastic deformation.
Correlation of the basic parameters of unidirectional solidification of the Pb‐Sn eutectic
Authors: Wolsczyński W. , Ciach R.
Published: January 2007

General conditions of the unidirectional solidification are used to control the process of Pb‐Sn eutectic solidification as well as to predict the desirable values of λ deciding about the physical properties of a final product.
Influence of gel inclusions on the mechanical behaviour of Gypsum
Authors: Raju K. S. , Godehardt R. , Hopfe J. , Pippel E.
Published: January 2007

In a single test tube system, gypsum crystals grown in alcoholic gel comprise of interpenetration twinned crystals at the interface towards the gel, whereas untwinned tabular crystals are observed at greater depths inside the gel. By indentation of the crystals with a microhardness tool and recording the indentation impressions by means of a scanning electron microscope (SEM) and a transmission electron microscope (TEM) it is found that the hardness of the tabular crystals is of the same order of magnitude as those of natural crystals of gypsum, whereas interpenetration twinned crystals show a remarkable increase in hardness. On studying the morphology of cleavage faces and on carrying out energy dispersive X‐ray analysis (EDXA), it is concluded that the increase in hardness of interpenetration twinned crystals with respect to tabular and natural crystals may be due to the role of the inclusion of gel particles during the growth. The implications are discussed.
Activity coefficient and incorporation of Phosphorus into epitaxial CVD Silicon
Authors: Kühne H.
Published: January 2007

The present paper is concerned with the dopant incorporation behaviour at high doping concentrations, at which the conditions for diluted solutions are commonly considered no longer fulfilled. The first part contains a brief discussion of the theoretical aspects of ideal, ideally diluted and real solutions, and Raoult's law as well as Henry's law are reduced to the general solution equilibrium, applied to dopant incorporation. The second part considers the dopant ionization equilibrium according to the conception of REISS, additionally taking into account the high deposition temperatures. It had been concluded that at high doping concentrations both the ionization equilibrium and the solution equilibrium of dopants behave analogous to real solutions, and both equilibria need a correction by special activity coefficients.
Dielectric and electrical studies on Samarium Oxide thin film capacitors
Authors: Chandra Shekab M. , Siva Kumar J. , Subba Rao U. V. , Hari Babu V.
Published: January 2007

Sm2O3 films were prepared by thermal evaporation using tantalum boats. Current‐voltage characteristics were drawn for different film thicknesses. The breakdown voltage and dielectric strengths were calcualted for different film thicknesses and the applicability of Forlani‐Minnaja relation was discussed. The effect of dc voltage on capacitance and tan δ was studied. The results were explained on the basis of Schottky barriers existing at metalinsulator interface which are due to the presence of oxygen vacancies. The presence of oxygen vacancies were established from thermoluminescence studies. The effect of ac voltage on capacitance and tan δ were also studied and the results were discussed.
Dielectric and electrical studies on as‐grown CeO2 films
Authors: Chandra Shekar M. , Hari Babu V.
Published: January 2007

Thin film capacitors of CeO2 were fabricated by thermal evaporation. The dielectric properties of these films were studied in the frequency range 0.05–16 KHz at various temperatures, starting from liquid nitrogen temperature to 390 K. The effect of annealing on capacitance and tan δ were studied for different frequencies. The behaviour was explained on the basis of relief in strain energy. The plot between current density and temperature was drawn, and from the slope of the plot the activation energy was calculated and found to be 0.52 ev. The results were discussed.
Hydrated metal halide structures and the HSAB concept
Authors: Balarew Ch R. , Duhlev R. , Spassov D.
Published: January 2007

A review of ligand coordinatio in the structures of hydrates of the bivalent Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn and Cd halide salts is made. Differences in the type of environment around the Me2+ are satisfactorily explained using the HSAB (Hard and Soft Acids and Bases) concept: in all structures the tendency for a preferable combination hard cation — hard ligand and soft cation — soft ligand is proved. The paper demonstrates the possibilities of the HSAB concept to solve crystallochemical problems of the type of ligand coordination in the structures.
Influence of low‐temperature thermocycling on anisotropy of the structural state of commercial purity Beryllium
Authors: Verkin B. I. , Lavrentev F. F. , Braude I. S. , Salita O. P.
Published: January 2007

The influence of low‐temperature cycling (300 ← 77 K) on the anisotropy of commerical purity beryllium structural state, obtained by uniaxial hot extrusion has been studied by means of X‐ray method. In initial samples the anisotropy of structural state is shown by the preferential orientation of grains relative to extraction axis.

Two types of experiments were carried out

Two types of samples were investigated the samples cut out along and across the extrusion axis. It was shown that cycling in the samples oriented across the extrusion axis led to essential change in initial structural state due to intense twinning. Considerable changes in structures of the samples oriented along the extrusion axis were not observed. The effects are intensified by load application.

Thermocycling leads to considerable decrease in grain size (form about 50 μm in initial state to about 30 μm after cycling) and decrease in structural state anisotropy.

Nature of the phenomena found is discussed.
Structure sensitivity of relaxation phenomena in NaCl and KCl crystals doped with some divalent impurities (II) effect of plastic deformation
Authors: Suszyńaska M. , Capelletti R.
Published: January 2007

By studying: 1/the role of dislocations in the origin of the C‐ITC‐peak in undeformed crystals, 2/ the effect of plastic deformation upon the behaviour of this peak, and 3/ the recovery of the deformation‐induced changes of the basic characteristics of this peak (HC, TMC) it has been confirmed that dislocation lines surrounded by the Cottrell‐like atmospheres can be considered as polarizable entities related with the high‐temperature dielectrical response of as cleaved NaCl and KCl crystals doped with divalent impurities. The Maxwell/Wagner model of polarization effects in heterogeneous dielectrics satisfactory accounts for the majority of the experimental data. The quantitative analysis of the results obtained yields some additional informations concerning the interaction‐ and motion‐parameters of the defects considered.
Influence of solidification of binary eutectic lamellar systems on surface tension driven convection in zero gravity conditions
Authors: Demo P. , Farkas L. , Kratochvil J.
Published: January 2007

The effect of solidification of the lamellar binary eutectic system on the onset of surface tension driven convection (so‐called Marangoni instability) is studied in a zero gravity environment. Some main general conclusions concerning the possibility for onset of the Marangoni convection within the melt can be drawn from the analysis, viz., the curvature of the free surface has a destabilizing effect on the onset of the flow; the increased perturbed heat transfer rate from the system stabilizes the melt; the onset of the solutal Marangoni convection closely depends on the ratio of the lamellae half‐widths and the solutal Marangoni instability is more sensitive against the perturbations than the temperature Marangoni one.
Role of Z1 centres in radiation hardening of NaCl:Ba2+ crystals
Authors: Narasimha Reddy K. , Lakshmipathi Rao M.
Published: January 2007

Radiation hardening studies of undoped NaCl and NaCl crystals doped with barium have been carried out both in the as‐grown state and after quenching them from 650°C. It is observed that the radiation hardening is more in doped crystals and the results are explained taking into consideration the role of Z1‐centres.
DC breakdown studies on CeO2 films
Authors: Chandra Shekar M. , Hari Babu V.
Published: January 2007

The electrical breakdown studies were made on Al—CeO2—Al thin film capacitors using dc voltage. The optical photomicrographs of the breakdown patterns were obtained at several stages of breakdown using universal optical microscope. Breakdown patterns seems to be originated at some inhomogeneity which may cause to form single‐hole breakdown and is followed by propagating mechanism. The results were discussed.
Thermoluminescence and optical absorption studies of NaCl: Gd2+ crystals
Authors: Narasimha Reddy K. , Subba Rao U. V. , Lakshmipathi Rao M.
Published: January 2007

Thermal annealing of X‐irradiated point defects in gadolinium doped NaCl crystal is investigated by Thermoluminescence (TL) and optical absorption methods. The results of the influence of pre‐heat treatment and optical bleaching on glow curves and the production of Z1‐centres are discussed.
Effect of AC and DC voltage on dielectric properties of CeO2 films
Authors: Chandra Shekar M. , Hari Babu V.
Published: January 2007

The capacitance‐voltage characteristics have been studied for both AC and DC fields of Al/Cerium Oxide/Al thin film capacitor structures. Compared to DC fields, these structures can withstand higher AC fields. Capacitance increases with increase in AC and DC fields. The former behaviour is explained on the basis of presence of oxygen vacancies and the latter one is attributed for the Joule heating phenomena. The presence of oxygen vacancies were confirmed from the thermoluminescence studies on these films.
A simple method to determine the real composition of LiNbO3 crystals
Authors: Földvári I. , Polgár K. , Voszka R. , Balasanyan R. N.
Published: January 2007

The shift of the UV‐absorption edge was applied to determine the real LiNbO3 crystal composition. The accuracy of the method is about 10−2 mole% using a simple commercial UV‐spectrophotometer. The effect of various impurities and other error sources are discussed.
Changes of the growth morphology in insb crystals pulled under the presence of ultrasonic vibrations
Authors: Hayakawa Y. , Kumagawa M.
Published: January 2007

In the Czochralski method, the effect of ultrasonic vibrations on the growth of InSb single crystals was investigated by observing the growth morphology. Remarkable changes which ultrasonic vibrations brought about were: (1) the crystal diameter, (2) the width of the facet region and (3) the inclined angle of non‐facet interfaces near the facet region for the (111) plane. After introducing vibrations, the crystal diameter decreased smoothly with growth time. However, both the facet width and the inclined angle reached each minimum value after 5 to 7 min regardless of the magnitude of vibrational output powers from 30 to 90 W, and they were in roughly proportional relation with each other. The change rates of crystal diameter and of facet width increased with vibrational powers. The decrease of crystal diameter was known to result from the rise of the melt temperature, which was brought by both the mixture of the melt and the thermal energy transformation due to ultrasonic vibrations. The change of facet width depended upon the melt flow itself in addition to the temperature rise.
The energy distribution in the two‐mode X‐radiation field inside perfect crystals
Authors: Bezirganyan A. P. , Bezirganyan S. E.
Published: January 2007

The intensity distribution of a two‐mode X‐radiation field on simultaneous interference of all four waves inside the perfect crystal in dependence on the absorption and availability of the symmetry center in crystal, as well as one the state of polarization and the angle of incidence of the primary beam is studied.
Calculation of the shear stresses in (111)‐ and (001) semiconductor substrates with film edges
Authors: Fischer A.
Published: January 2007

Assuming a film‐edge induced stress distribution in an isotropic crystal, the shear stresses in the glide systems of a diamond‐type semiconductor substrate are calculated. Quantitative information on magnitude and position of the respective shear stress maxima is obtained in dependence on crystal orientation and technologically relevant film configurations.
Automated growing of large single crystals controlled by melt level sensor
Authors: Eidelman L. G. , Goriletsky V. I. , Nemenov V. A. , Protsenko V. G. , Radkevich A. V.
Published: January 2007

The process of single crystal pulling is considered with simultaneous starting material make‐up into the melt and heater temperature control in response to a signal generated by the electronic contact melt level sensor, viz.: (i) conditions ensuring the radial broadening steadiness; (ii) effect of melt level displacement, melt temperature changes, changes of solid/liquid interface shape, melt evaporation on the growing crystal diameter; (iii) conditions of crystal purification from impurities and uniform distribution of dopant.
Diffuse X‐ray scattering study of the temperature variation of elastic constants in indium arsenide
Authors: Orlova N. S.
Published: January 2007

The elastic constants of indium arsenide have been determined in the temperature range from 80 to 750 K on n‐type samples with a carrier concentration of about 8 · 1017 cm−3 by Wooster's method from the measurements of the thermal X‐ray diffuse scattering intensities. An average decrease in the elastic constants with increasing temperature over the above mentioned temperature range is found to be about 8%.
A decomposition study of a eutectoid CuAl alloy
Authors: Terziev L.
Published: January 2007

A study of the eutectoid decomposition of a Cu‐11.8wt.%Al alloy was carried out by means of differential scanning calorimeter and an electron microscope. The activation energies of eutectoid and peritectoid reactions were determined.
A complex method for structural investigation of GaAs1−xPx epitaxial layers grown on GaAs substrates
Authors: Petrov Sr. , Popov A. , Atanasova R. , Ivanov Iv.
Published: January 2007

A universal X‐ray diffractometer is used for the structural complex investigation of GaAs1−xPx epitaxial layers, grown on the (100) face of GaAs substrate. Information is obtained from the analyses of diffraction patterns for some qualities of the epitaxial layers: crystallographical orientation, composition, thickness, as well as structure of the transition region. The suggested complex method has important advantages against the standard Laue method. It is far easier express and convenient for serial investigations.
The reversion of smoky quartz coloration in crystals with induced growth striations
Authors: Bernhardt H.‐J.
Published: January 2007

Induced growth striations in quartz crystals grown from Al‐containing material have been investigated after X‐raying them. Earlier results (Bernhardt, Alter) showed that the stripes may occur as strong colored ones on a light background or as light stripes on high coloration background. This behaviour depends on the growth region regarded, and the applied X‐ray dose. The position of the stripes may become displaced in dependence of the X‐ray dose. The present paper developes a model which may describe this effect only using the diffusion law, the smoky quartz centre model according O'Brien and the Al3+/Na+‐distribution in the crystal. Our results must be taken into account when interpreting the growth striations.
On the influence of various pre‐ageing treatments on the structure changes taking place at elevated temperatures in alloys of the type AlZn5Mg1
Authors: Korngiebel E.
Published: January 2007

Investigated were two alloys of Type Al‐5 wt% Zn‐1 wt% Mg, one of them contained additionally 0.2 wt% of Mn, Cr, Fe as well as Si (technical alloy), be means of hardness and TEM investigations.
Effect of high oxygen doping on the minority carrier lifetime in heat‐treated silicon crystals
Authors: Glinchuk K. D. , Litovchenko N. M. , Salnic Z. A. , Skryl S. I.
Published: January 2007

Effect of high oxygen doping on thermally induced changes in the minority carrier lifetime τ in 800 °C heat‐treated silicon crystals is studied and analyzed. Deteriorated τ values in prolongly annealed highly oxygen‐enriched Si crystals compared with those found in annealed oxygen‐poor crystals, are observed. This is explained by an appearance in prolongly annealed highly oxygen‐enriched silicon crystals of oxygen‐induced microdefects which are effective in the minority carrier recombination.
Melting temperature and debye temperature of ternary chalcopyrite semiconductors
Authors: Samanta L. K. , Ghosh D. K. , Bhar G. C.
Published: January 2007

Band state concept has been used for the first time to explain the Melting temperature and Debye temperature of ternary chalcopyrite semiconductors. The experimental results agree quite well with those evaluated from this model. Finally we derive a correlation between the two termperatures.
Possibilities of the quantitative characterization of intermetallic phases in the cast structure of aluminium alloys
Authors: Griger Á. , Lendvai A. , Stefániay V. , Turmezey T. , Hidvégi É.
Published: January 2007

The quality and quantity of intermetallic compounds in a commercial aluminium alloy based on 99.5% Al purity are responsible for the final properties of products. Compositional and spatial distribution of intermetallics in the matrix are determined besides the chemical composition by the circumstances of solidification fixed with casting conditions. Therefore in order to get a cast structure, corresponding to the quality favourable in further processing, the casting process should be controlled in accordance with the formation of intermetallic compounds.

The main and unavoidable impurities in aluminium alloys are iron and silicon. Quality demand requires, however, iron and silicon to be considered as alloying elements. Methods used in the investigations of AlFe and AlFeSi phases in function of crystallization are reported in this paper.