bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of point defect parameters of solids on the basis of a defect formation model of melting (I)
Authors: Uvarov N. F. , Hairetdinov E. F. , Bollmann W. 
Published: January 2007

AbstractIt is proposed that the melting process is governed by the creation of lattice defects followed by a relaxation of the lattice in the vicinity of the defects. At the melting point Tm the mole fraction xL of defects within the melt is given by xL = L/ho (L heat of fusion; ho formation enthalpy of defects within the solid).
Estimation of point defect parameters of solids on the basis of a defect formation model of melting (II). Vacancy formation enthalpy in relation to the heat of fusion and the increase of volume due to melting
Authors: Bollmann W. , Uvarov N. F. , Hairetdinov E. F. 
Published: January 2007

AbstractThe mole fraction of vacancies within melts at their melting points is found to be xL = = 0.125 in the case of elements (with exception of inert gases), alkali halides, binary oxides and organic compounds. As to inert gases it is xL = 0.194. The formation enthalpy of vacancies (Schottky defects) is given by hS = L/xL (L heat of fusion) in every case. The increase of volume due to melting can be explained well by the vacancy model of melting: ΔV = VSxL (VS formation volume of Schottky defects).
Lattice parameter determination of superlattices
Authors: Berger H. , Rosner B. , Schikora D. 
Published: January 2007

AbstractA method for determination of absolute lattice parameters of superlattices is described‐which does not use any relations to substrate reflections. For superlattices having tetragonal or trigonal symmetry, three parameters are to be determined. For this purpose, the diffraction angles of two reflections are measured, the third angle is obtained from the incidence angle difference of two single reflections of a “reflection group”. The peak shift caused by partial superposition of the single reflections, which occurs at larger superlattice periods, is corrected by means of simulation calculations. As an example, the results obtained on a PbTe/(Pb, Sn)Te superlattice are given and discussed.
Oxide‐free etching of (100) InP surfaces
Authors: Knauer A. , Hirsch D. , Staske R. , Zeimer U. 
Published: January 2007

AbstractWe report several combinations of chemical preparation procedures for selective cleaning of InP (100) surfaces in connection with storage procedures. A complex of analytical methods was used to get information about the surface state, the morphology, and the perfection of the surface. Using a standard etch procedure developed by KURTH et al. a post‐deoxidation by small concentrated HF or HNO3 is sufficient to get oxide‐free, clean InP (100) surfaces even after a storage in methanol for some hours.
Dielectric investigations on a binary system showing a “filled” SA Phase
Authors: Stettin H. , Kresse H. 
Published: January 2007

AbstractA binary system of a double swallow‐tailed compound and a substance with a strong polar terminal group shows a pronounced induced SA phase. Investigations of the static dielectric anisotropy indicated a deviation from the simple mixing rule which was empirically introduced. We derived a better approximation taking into account the different molecular volumes of the substances. An unexpected increasing mobility of the strong polar molecules could be detected by relaxation measurements. This may be connected with a change in the short range order of the strong polar compound which is caused by the repulsive forces of the molecules.
The current understanding of epitaxial CVD silicon layer doping in the light of modeling and theory development (IX).Verification of the Multi‐wafer Autodoping Model
Authors: Kühne H. , Malze W. , Schröder K.‐W. 
Published: January 2007

AbstractThe multi‐wafer problem of lateral autodoping has been investigated in a rectangular, horizontally arranged epitaxy reactor by arranging on the top‐side As‐diffused source wafers and smaller high‐resistivity, p‐type sensor wafers which were for indicating lateral autodoping dose after a short‐lasting intrinsic layer deposition. Wafers were evaluated by sheet resistance measurements, IR‐determination of layer thickness and spreading resistance profiling. A linear increase of lateral autodoping dose along the susceptor has been proved and a linearly increasing parasitic dopant partial pressure deduced. These findings give evidence for the validity of the multi‐wafer model of lateral autodoping previously developed by the authors.
Study of the influence of additives on some parameters of batches for the synthesis of a light permeable polycrystal of yttrium oxide
Authors: Chomakov Iv. , Bogdanov B. I. , Petrov Sr. , Iliev J. 
Published: January 2007

AbstractFor obtaining light permeable ceramic of yttrium oxide, the initial batch should be highly sinterable. The influence of additives of ZrO2, ThO2, BeO, Gd2O3, Ga2O3, La2O3 and ThO2 + Nd2O3 on the particle‐size of the batch and the occurrence of defects in the unit cell of Y2O3 is studied. It has been found that the additives influence the particle‐size of the batch and increase the specific surface 4 times. The dependence of the unit cell parameter of Y2O3 on the ion radius of the additive is determined by means of X‐ray analysis. The measured density of sintered samples of the batches obtained is 99.9–99.96% of the X‐ray one and the light permeability at λ = 0.3–10 μm is from 60 to 92%.
VPE growth of InGaAS/InP structures using the hydride system
Authors: Diegner B. , Eberle T. , Jacobs K. 
Published: January 2007

AbstractSome results on the VPE growth of InGaAs/InP structures in the hydride system using a single chamber horizontal reactor are described. The effect of partial pressures of the reactant gases and bypass‐HCl on epitaxial growth of InGaAs is discussed. The GaCl partial pressure was found to be the deciding growth parameter.
Formation of α‐Al2O3 by thermal decomposition of basic aluminium chlorides at low temperatures
Authors: Brand P. , Troschke R. , Weigelt H. 
Published: January 2007

AbstractBasic aluminium chloride gels and the crystalline salt AlCl3 · 2 Al(OH)3 · 6 H2O are thermally decomposed to an amorphous product in a first step at low temperatures. If the reaction gas is rapidly removed the amorphous decomposition product directly transforms to corundum at increased temperature. Starting from gels the α‐Al2O3 formation begins at 420 °C, transformation of the crystalline salt at 530 °C. Structural similarities of precursor compounds and corundum are discussed as a reason for this behaviour. High contents of HCl and H2O in the atmosphere surrounding the specimen result in decomposition to transition aluminas at increasing temperature, which are transformed into α‐Al2O3 above 1000 °C.
Characteristic of the photoconductivity of thallium monoselenide
Authors: Hussein S. A. , Nagat A. T. , Mohamed N. M. 
Published: January 2007

AbstractSystematic investigations on thallium monoselenide single crystal photoconductivity were reported at 300 K as a function of excitation intensity, side illumination, and wavelength. The samples were prepared using Bridgman technique. The photoconductivity as a function of the modulation frequency of the incident light was plotted at different values of light intensity. The effect of light intensity on the photocarrier lifetime was studied. The relation between the photocurrent and applied voltage at different values of light intensity was represented graphically. Side illumination effect in all these relations was checked. The spectral distribution of the photoconductivity of TlSe in the spectral region 1.24 ev to 1.77 ev was measured, and the energy gap was evaluated. All results were discussed and analyzed. Studies for such samples are very important and necessary in order to understand their use as photoconductor.
Study of calcium phosphate precipitation at 37 °C
Authors: Kibalczyc W. 
Published: January 2007

AbstractThe nature of the calcium phosphate formed when equal volumes of 20 mM CaCl2 and 15 mM or 12 mM K2HPO4 with pH 7.4 are rapidly mixed at 37 °C has been investigated by following the pH of the suspension as a function of time, by calorimetric and light scattering methods, chemical analysis and TEM. It is found that in the early stages of this process, there appears a spherular amorphous form of calcium phosphate, called ACP1, which transforms into a floccular amorphous form, called ACP2. We suggest that this transformation is solution‐mediated. ACP2 has not previously been clearly described as a separate phase and has not before been shown to be amorphous.
On the stereochemistry of 7‐[1(2‐carbomethoxyanilino)‐1‐(pyridyl)‐methyl]‐quinolin‐8‐ol (CMAP‐oxine)
Authors: Rericha A. , Seidel I. , Röbisch G. 
Published: January 2007

AbstractC23H19N3O3, P1, a = 11,683(3), b = 7.740(2), c = 14.445(3) Å, α = 131.02(8), β = 95.43(8), γ = 95.02(8)°, Dx = 1.328 Mg · m−3, V = 0.9614 · 10−27 m3, Final R = 0.059 for 2905 symmetrically independent reflections (|F0| ≧ 3σ(F0)). The intensities were measured with an automatic diffractometer. There are two molecules in the unit cell. The substance is not tridentat in potentially coordination behaviour; coordination takes place (twodentat) on the oxine group.
A surface‐near stress resulting from Tamm's surface states
Authors: Gräfe W. 
Published: January 2007

AbstractFrom the energy band approximation of KRONIG and PENNEY and TAMM'S model of surface states a contribution of the electrons localized at the surface to the surface tension of a solid has been deduced. The results illustrate the difference between the surface tension and the surface energy in the case of a solid. It has been explained how the above mentioned contribution to the surface tension is connected with the existence of a surplus surface‐near lokal stress.
Infrared optical characterization of epitaxial layer – substrate systems (II). Experimental results for AlxGa1−xAs/GaAS
Authors: Riede V. , Sobotta H. , Neumann H. , Gregora I. , Kamba S. , Vorliček V. 
Published: January 2007

AbstractInfrared reflectance and transmittance spectra and Raman scattering spectra of the epitaxial layer‐substrate system AlxGa1−xAs/GaAs with compositions in the range x = = 0.08–0.49 are measured in the wavenumber range from 40 to 4000 cm−1. In analysing the spectra in terms of the respective theoretical relations for an optical two‐layer system the thickness of the layers, the optical mode characteristics and the free carrier parameters are determined. From a comparison with existing literature data for AlxGa1−xAs it is concluded that infrared optical measurements on epitaxial layer‐substrate systems can be successfully employed to evaluate the material parameters of epitaxial layers with thicknesses down to a few micrometers.
Characteristics of GaAsAlGaAs (SCH) lasers grown by low‐temperature LPE technique
Authors: Diaz P. , Prutskij T. A. , Sanchez M. , Larionov V. R. , Khvostikov V. P. 
Published: January 2007

AbstractIn this paper we report the performance and study of GaAsAlGaAs (SCH) laser. The structures were grown by a new variant of the LPE‐technique with temperatures regimes lower than 600 °C. The Low Temperature LPE‐technique, recently propoused by ANDREEV and coworkers at the IOFFE‐Physico‐Technical Institute exhibit growth rates of the growing layers as low as that corresponding to MBE or MOCVD techniques. In this way, it is possible to obtain and control layer thicknesses in the structure of the order of tens to hundreds of Ångströms. Laser heterostructures with active layer thickness of 30 nm, were performed and the lowest threshold current density of 437 A/cm2 for a cavity length of 1.33 mm were obtained. A typical growth process is described and a SEM structure microphotograph is shown. The dependences of the threshold current density Jth and the differential quantum efficiency ηd with the cavity length L are reported. From these data, other laser parameters are evaluated such as internal optical losses α1, internal quantum efficiency ηi and the dependence of the maximum of the gain factor against the nominal current density Jnom at threshold. This dependence was compared with the theoretical predictions and a good agreement was found.
On the morphological instability of the growing crystals (IV). The effect of supersaturation inhomogeneity upon the morphological stability of KDP single crystals
Authors: Staynova M. , Nanev Chr. 
Published: January 2007

AbstractThe diffusion‐induced inhomogeneity in the supersaturation on close packed faces of KDP crystals, growing from aqueous solutions has been investigated. The interferometrically found values of the concentration difference on the crystal edge and in the centre of the most closely packed face {100} were compared with the theoretically expected concentration nonhomogeneities calculated by means of CHERNOV's formula. The comparison has been performed especially for the moment when the KDP crystals lose the stability of their polyhedral shape and gradually acquire a skeletal form. A fairly good coincidence was found.
Mechanism of the oxygen‐stimulated deactivation of RuyTi1−y‐oxide overlayers on Ti studied by XPS, SEM and electrochemical techniques
Authors: Wagner N. , Kühnemund L. 
Published: January 2007

AbstractBy means of wet oxygen exposure the stability of RTO anodes has been observed. The deactivation is due to ruthenium loss via unstable higher surface oxides in a long time regime. As follows after uneffective subsurface annealing procedure the catalytic durability is reduced drastically by erosion stimulated increasing ruthenium loss of inhomogeneous active layer surfaces.
Ultrasonic relaxation studies in the liquid crystal 80CB
Authors: Venkatacharyulu P. , Gupta A. V. N. , Prasad N. V. L. N. , Rao J. V. 
Published: January 2007

AbstractThe variation of the ultrasonic velocity with temperature in the liquid crystal 4′‐n‐octyloxy‐4‐cyanobiphenyl (80CB) at four different fixed ultrasonic frequencies is studied. From these studies various relaxation parameters like the adiabatic relaxation time, velocity at zero frequency, in the vicinity of isotropic‐nematic phase transition and velocity at infinite frequency are estimated. From these parameters the relaxation mechanism in the vicinity of isotropic‐nematic phase transition is studied and the results are discussed.
The investigations on the synthesis of zeolite ZSM‐5 (I)
Authors: Wilkosz J. , Stobiecka E. , Dudek B. 
Published: January 2007

AbstractThe effect of the composition of reacting mixtures on the crystallinity of zeolite ZSM‐5 was investigated. The mixture of ethanol and ammonia was used as a templating agent. The quantitative determination of the phase composition of the obtained preparations was made on the ground of X‐ray diffraction. The ZSM‐5 zeolite of ab.90% phase purity, contaminated with mordenite, quartz and amorphous material, was obtained.
X‐ray diffraction studies of interdiffusion in InPGaP powder blends
Authors: Voland U. , Černý R. , Deus P. , Bergner D. , Fenninger G. 
Published: January 2007

AbstractInterdiffusion in the InPGaP solid solution system is investigated by means of X‐ray diffraction of annealed powder blends. An activation energy of Q = (3.15 ± 0.3) eV for the interdiffusion process in the temperature interval 650… 725 °C was found. Diffusion parameters obtained by means of this method for InPGaP and InAsGaAs are discussed on the basis of lattice and atomic characteristics.
Macrosegregation of alumina in LiNbO3 single crystals
Authors: Erdei S. , Szaller Zs. , Raksányi K. 
Published: January 2007

AbstractThe macrosegregation of Al impurities has been studied in Czochralski grown LiNbO3 single crystals. Macrosegregation profiles determined by neutron activation analysis are presented and compared to predictions to the solutions of the neglect of parallel motion (NPM) model. A brief description of this model is given and a new formula is suggested for the interface segregation coefficient, k*, which accounts for different mechanisms of impurity incorporation due to the onset of criticalities. Optimization of model parameters led to fairly good agreement between observed and calculated profiles. Thus we have been able to give an upper estimate for the equilibrium distribution coefficient (k0) of Al. A numerical procedure was developed to assess the errors of the optimized model parameters.
Properties of some perovskites synthesized under pressure
Authors: Troyanchuk I. O. , Ges A. P. , Pastushonok S. N. , Pavlov V. I. , Balyko L. V. , Shipilo V. B. 
Published: January 2007

AbstractInterstitial solid solutions with the perovskite – like structure were synthesized by solid phase reactions at high pressure and temperature. The synthesis conditions of single phased samples, their stability on heating in air were determined. The magnetic and electrical properties were measured.
Mass spectrometric analysis of gaseous crystallization medium, growing, and some properties of α‐Al218O3 crystals
Authors: Arzumanyan G. A. , Bagdasarov Kh. S. , Ryadnov S. N. , Garnikyan A. V. 
Published: January 2007

AbstractSome gas phase processes during the vacuum vertical directed crystallization of α‐Al2 18O3 are studied in this paper. An effect of these processes on the H, C, N concentrations in the crystals is discussed. The detected pulsations of partial H2 and C18O pressures are a result of bubble destruction at the melt‐gas interface. The C18O bubbles are formed because of chemical interaction between the melt and carbon‐containing phases of container material. Besides the container wall, the H2 bubbles can be generated also at the crystallization front supersaturated by H2. The perfect α‐Al2O3 and α‐Al2 18O3 crystals grown under the same conditions have noticeable differences of their density, microhardness and lattice parameters. This is explained by an isotopic substitution effect.
Investigation of amorphous to crystalline transitions in InSe thin films
Authors: Rao S. Ramchandar , Nagabhooshanam M. , Babu V. Hari 
Published: January 2007

AbstractThe amorphous to crystalline transitions in InSe films have been investigated by different techniques. InSe compound was prepared from non‐stoichiometric amounts of indium and selenium in vacuum. The electrical conductivity and thermoelectric power measurements were made in films of different thicknesses and annealed for different times. TEP studies revealed that the films are p‐type. The conductivity studies have shown transition from amorphous to crystalline. The transition temperature is found to decrease with increase in (i) the thickness of the film, (ii) the time of annealing. Electronmicrographs and selected area diffraction patterns on as‐grown and annealed films have been taken and correlated with the conductivity results. The mechanism involved in the amorphous to crystalline transitions has been discussed.
Effect of pH on the electrical conductance of saturated aqueous solutions of KH2PO4 and its solubility
Authors: Sangwal K. , Olczyk E. 
Published: January 2007

AbstractThe specific conductivity of saturated aqueous solutions of KH2PO4 and its solubility are investigated in the pH range between 2.5 and 6.3. It is found that the values of specific conductivity and solubility show minima at pH of about 3.5 and 4, respectively. These observations are discussed in terms of the presence of a variety of species of different concentrations in saturated solutions of different pH. The conductivity data reveal that the solutions are highly associated. The presence of species other than H2PO4− and K+ explains the experimentally observed deterioration in the quality of KDP crystals from solutions of pH deviating from the natural value.
Microhardness of Hg1−xCdxTe and Hg1−xZnxTe
Authors: Fissel A. , Schenk M. 
Published: January 2007

AbstractThe microhardness of Hg1−xCdxTe and Hg1−xZnxTe has been measured on monocrystalline samples of Bridgman and THM crystals as a function of composition x by means of Vickers indentation measurements at room temperature. The curves show maxima of about 830 MPa at x ≈︁ 0.75 for Hg1−xCdxTe and of about 1700 MPa in the range 0.65 ≦ x ≦ 0.8 for Hg1−xZnxTe. The hardness‐relaxation behaviour has been measured on {111} samples in order to obtain the internal stress level and to investigate the stress‐relaxation behaviour. The theoretical hardening rate dH/d(x)0.5 was compared with experimental values.
Synthesis of AgIAgClCuI solid solutions for ice nucleation studies
Authors: Sivanesan S. , Gobinathan R. 
Published: January 2007

AbstractLattice parameter calculation and the nucleation temperature of AgIAgClCuI system are reported in this study. By vacuum fusion three samples of different molar compositions were prepared. The formation of the cubic solid solution of the above system was confirmed by X‐ray analysis. It is found that the 50:25:25 mole% composition of AgIAgClCuI has the highest nucleation temperature of −1.0 °C, which is far greater than −2.53 °C, −4.02 °C and −2.26 °C for pure AgI, AgCl, and CuI, respectively.
Questioning klinowski's concept of isomorphous substitution of silicon by aluminium in the framework of silicates
Authors: Lutz W. , Grossmann A. , Bülow M. , Gross Th. 
Published: January 2007

AbstractSilicalite was treated in an alkaline solution of aluminate following Klinowski's instruction for ‘fine tuning’ of zeolitic catalysts. Instead of an isomorphous substitution of framework silicon by aluminium, a partial phase transformation of the silicate into an Al‐rich aluminosilicate gel was observed. A surface re‐alumination of residual crystals takes place.
Doping of PbTe and Pb1−xSnxTe with gallium and indium
Authors: Duguzhev Sh. M. , Makhin A. V. , Moshnikov V. A. , Shelykh A. I. 
Published: January 2007

AbstractPrecipitations in Indium and Gallium‐doped PbTe, SnTe and Pb1−xSnxTe are investigated. The compositions of the precipitated phases are PbGa6Te10 SnGa6Te10 and PbIn6Te10 for binary compounds. For Pb1−xSnxTe the precipitated phase composition corresponds to the continuous solid solutions Pb1−zSnzGa6Te10. Basic properties of the new compounds are determined. Their resistivity being of 5 ÷ 6 orders higher than that for Pb(Sn)Te, the anomalous transfer phenomena, observed in highly Ga(In)‐doped samples can be explained on the basis of the barrier model.
Theoretical approach to the mechanoluminescence excitation in solids
Authors: Chandra B. P. , Rahangdale Yuvraj 
Published: January 2007

AbstractThe present paper reports the results of some theoretical approach made to the studies of Mechanoluminescence (ML) of solids. It is found that the ML intensity depends on three major factors, the ML efficiency, damping factor, and elastic complience. It is concluded that the non‐viscous solids with high elastic compliance possessing luminescence centres with appropriate efficiency may exhibit intense ML. It is shown that the ML emission should take place only during the time at which there will be a change of applied pressure with time. There should be a phase difference between the applied pressure and the emitted ML signal.
Kinetic investigations within the transition region from polyhedral to skeletal growth mode (I). Growth kinetics of the basal face of zinc single crystals under diffusion conditions
Authors: Iwanov D. 
Published: January 2007

AbstractThe effect of diffusion in the vapour phase on the kinetics of growth of zinc single crystals in the presence of argon has been studied. The shift of the basal face in normal direction as a function of the time has been measured at constant temperature and supersaturation and argon pressures varying within the range 5–250 Torr as well as in vacuum 1 × 10−6 Torr. It has been established that the crystal size R changes with the time t following a linear and a parabolic law in the kinetic and the diffusion regimes, respectively. The kinetic critical size Rk for the transition from a kinetic to a diffusion regime has been experimentally obtained. A relatively good agreement is found between the experimentally established and theoretically calculated values of the critical size. The problems related to the transition of the basal faces of zinc single crystals from a kinetic to a diffusion growth mode is discussed.