bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of Formation of Cadmium Oxalate Liesegang Rings
Authors: Arora S. K. , Abraham Tomy , Godebole R. S. 
Published: January 2007

AbstractQualitative and semiquantitative study of the Liesegang rings formed by the reaction of oxalic acid and cadmium chloride in the acidic range of pH in silica hydrogel is made. The behaviour of Jablczynski's space constant and Morce‐Pierce's time constant at various temperatures, pH and concentration of outer electrolyte is studied. The possible mechanisms for the above observed behaviour are suggested. The deviations from Isemura's general obserations are interprerted by considering two particular aspects, viz., comparatively larger crystals constituting the rings and the irreversibility of inner and outer electrolytes.
A thick window pAl0.7Ga0.3As‐pGaAs‐nGaAs concentrator Solar Cell
Authors: Díaz P. , Hernández L. , Rodríguez J. A. , Romero R. 
Published: January 2007

AbstractThick window pAl0.7Ga0.3As‐pGaAs‐nGaAs solar cells are reported being grown by forced cooling LPE. Device evaluation shows an 18% maximum conversion efficiency at room temperature.A method for calculating cell conversion efficiency upon knowledge of internal collection efficiency, open circuit voltage and short circuit current is also devised.
The monoclinic modification of Lead Phthalocyanine – a Quasi‐one‐dimensional Metal with characteristic order of molecular dipoles
Authors: Przyborowski F. , Hamann C. 
Published: January 2007

AbstractLead phthalocyanine (PbPc) crystallizes in a monoclinic modification with characteristic order of molecular dipoles. Japanese data on unit cell and space group were not to be confirmed by X‐ray and electron diffraction investigations.A group‐theoretical classification of energy levels of the molecule may result from the C4v symmetry of the shuttlecock‐like molecule. The space group P 21/b of the crystalline solid leads to the state of an antiferroelectric molecular crystal. In addition to earlier given microscopical explanation of the switching phenomenon a phenomenological solid state model of switching between semiconduction and metallic quasi‐one‐dimensional behaviour of PbPc is given.
A model study of the growth of crystals consisting of a small number of metal atoms by the Hückel molecular orbital method (I). Addition of One atom to small crystals
Authors: Delineshev S. P. , Bliznakov G. M. 
Published: January 2007

AbstractThe paper deals 1) with the regularities of the formation of (N + 1)‐atomic clusters during the growth of N‐atomic one‐, two‐, and three‐dimensional crystals and 2) with the distribution with respect to stability of the (N + 1)‐atomic clusters. The N‐atomic crystals have the structure of a hypothetical metal with a simple cubic lattice and a small number of one‐electron atoms. The binding energy (BE) of the clusters calculated by the Hückel molecular orbital method was assumed to be a measure of their stability. Interactions between nearest‐neighbours only were taken into account.The most stable (N + 1)‐atomic cluster formed from a one‐dimensional crystal is that in which the N + 1‐st atom is bonded to the end atom of the N‐atomic one‐dimensional crystal.For two‐dimensional crystals, the N + 1st atom forms the strongest bond with an atom from the diagonal of the square.With three‐dimensional crystals, the N + 1st atom is most strongly bonded to a corner atom of the small crystal.The inhomogeneity in the bond energy of the N + 1st atom to a surface atom of the small N‐atomic crystal decreases with increasing N.According to earlier studies of ours, the BE per atom increases, whereas the mean energy of a nearest‐neighbour bond decreases with increasing N.
Temperature profile and homogeneity of the growth rate of CVD Silicon from SiH4‐HCl‐H2 mixtures
Authors: Kühne H. , Morgenstern Th , Kühne Ch. 
Published: January 2007

AbstractWith the aid of the methods of the statistical design of experiments for each wafer site (x) on the graphite susceptor an empiric polynomial was obtained for CVD epitaxial silicon from SiH4–HCl–H2 mixtures, linking the growth rate vepi to the process parameters p0, p0HCl, and T(x). By means of the statistical model optimum temperatur characteristics along the susceptor were selected and discussed for specific deposition conditions.
Intergrowth and stacking faults in the Sm5Co19 Phase
Authors: Takeda S. , Komura Y. 
Published: January 2007

AbstractAn electron microscope observation was made on the binary Sm‐Co alloy. One‐dimensional lattice images of Sm5Co19 taken with the incident beam parallel to the [010] and [110] directions of the hexagonal axis showed many stacking faults.The intergrowth with the Sm2Co7 phase was observed in the matrix of the Sm5Co19 phase, the analysis being based on the thickness of blockj layers estimated by the distance of lattice fringes.
Surface Roughness and Kinetics of Spontaneous Transformation of Negative Crystals
Authors: Nenow D. , Trayanov A. , Pavlovska A. 
Published: January 2007

AbstractSpontaneous isothermal transformation of negative crystals (vapcur inclusions) at temperatures close to the melting point is experimentally studied. Linear dependence of the transformation rate on supersaturation is established. This result shows that the evaporating crystal surfaces of the inclusions are moleculary‐rough. Surface self‐diffusion has no appreciable contribution to the transformation process of the molecularly‐rough surfaces of diphenyl.
Growing Single Crystal Corundum Tubes by Verneuil Technique in Stable Conditions
Authors: Borodin V. A. , Brener E. A. , Steriopolo T. A. , Tatarchenko V. A. , Chernishova L. I. 
Published: January 2007

AbstractThe authors analyze the process of corundum tube growth by modified Verneuil's method from the viewpoint of its stability. The article shows that the process is stable in the case of thin‐walled tubes and becomes unstable when the tube wall thickness exceeds a certain critical value which is known to be below the capillary constant. The critical thickness of the tube wall grows with a decrease of the heat flux density differential from the burner along the furnace muffle and with an increase of the tube's outer radius.As a result of a process of crystal growth under preset conditions constant cross‐section single crystaal corundum tubes have been obtained.
Kinetics of the Incorporation of Dopants into Epitaxial CVD Silicon
Authors: Kühne H. 
Published: January 2007

AbstractStarting from the gas‐phase‐transport‐controlled and reaction‐controlled incorporation mechanisms and the equilibrium incorporation of the dopants a critical study of the adsorption model is carried through, as a result of which a model of adsorption is proposed. This modified model reflects the incorporation concentration of the dopants as a function of the layer growth rate and contains the equilibrium incorporation of dopants as a border‐line case for a layer growth rate of zero.
Influence of Quenching on Microhardness and Dislocation Mobility of Doped NaCl Crystals
Authors: Boyarskaya Yu. S. , Zhitaru R. P. , Linte M. A. 
Published: January 2007

AbstractThe effect of quenching on microhardness and dislocation mobility of NaCl:Ca and NaCl:Pb single crystals was studied. Both the decrease and increase of these parameters in quenching occurred depending on the type and concentration of impurity and quenching temperature. The absence of correlation between the changes of microhardness and those of dislocation ensemble mobility which resulted from the quenching, has been found first. The conditions of the observation of this phenomenon were revealed and the interpretation of the experimental facts was proposed.
The Influence of the Frequency on the Electrooptic Behaviour of Liquid Crystalline 4,4′‐Bis‐n‐pentyl‐azoxybenzene
Authors: Kresse H. , Keil M. , Deresch S. , Spott G. , Demus D. 
Published: January 2007

AbstractThe threshold voltage and the rise time of planar, homeotropic and twisted nematic layers were investigated in dependence of the frequency and the temperature. A strong increase of threshold voltage and rise time could be observed in the region of the dielectric relaxation frequencies between 0.1 and 1 MHz. The results were compared with those of the dielectric measurements.
An analysis of the behaviour of the sead crystals in batch crystallization
Authors: Baumann Karl‐Heinrich 
Published: January 2007

AbstractThe population density function of seed crystals, well defined at the beginning of batch crystallization experiments undergoes a strong deformation in the course of the process. A mathematical model, developed on the base of the generally accepted equations of the kinetics of crystallization and the population balance as a function of the crystal size and the process time is not suitable to describe such a behaviour.
Incorporation of dopants into epitaxial CVD‐Silicon layers and incorporation equilibrium
Authors: Kühne H. 
Published: January 2007

AbstractBased on the temperature dependence of the layer growth rate influence on the incorporation of dopants into epitaxial silicon the range of validity of an incorporation equilibrium between dopants in the gas phase and in the layer is discussed. Additional to the borderline case of an infinitely low layer growth rate the incorporation equilibrium is equally important to high layer deposition temperature. For this region deducing the incorporation enthalpy from the temperature dependence of the incorporation of dopants proves adequate.
Proposal for general principles for the construction of fully descriptive polytype Symbols
Authors: Dornberger‐Schiff K. , Ďurovič S. , Zvyagin B. B. 
Published: January 2007

AbstractExperience with polytype families of layered structures and the theory of OD structures consisting of layers made it possible to elaborate generally applicable principles for a full description of polytypes by symbols. According to these principles, the exact stacking sequence of building layers (BLs) in any given polytype may be described by a symbol which, in general, has the form
The Behaviour of Zinc in GaP Synthesis by the SSD Technique
Authors: Koi H. , Buhrig E. , Hein K. , Geidel B. 
Published: January 2007

AbstractIn this paper the principle of GaP synthesis by the SSD technique is described followed by a discussion of the results obtained in studying the transfer of an impurity such as the highly volatile zinc from the phosphorus source or gallium melt into GaP crystals. The radionuclide Zn65 was used as a tracer to determine the concentrations of zinc in the phases involved in the process of synthesis. The results of these studies are compared with calculated values.
Facet Formation on Near (111) Silicon Surfaces and the Desorption Energy of SiCl2 Adatoms
Authors: Van Der Putte P. , Giling L. J. , Bloem J. 
Published: January 2007

AbstractSilicon wafers which have a small misorientation from (111) become facetted, when they are etched beyond a critical HCl concentration. This facetting can be explained by the action of a second etch mechanism which directly attacks the surface between the steps. In this way enough new steps are generated to give a proper response to the desired etchrate. In BCF language: the spiral dissolution around a dislocation containing a screw component can become dominant over the etching process which occurs by a set of parallel steps, when beyond a critical HCl concentration the density of steps inside the shallow pit exceeds the density of the parallel steps due to the original misorientation. From the slope of the shallow pits at the critical HCl concentration a desorption energy for SiCl2 adatoms of around 60 kcal/mole could be calculated.
The Influence of High Temperature Predeformation on Ductility of LiF and BaF2 Single Crystals
Authors: Berezhkova G. V. , Skvortzova N. P. , Chormonov T. H. 
Published: January 2007

AbstractThe effect of high temperature predeformation on deformation characteristics of ductile LiF and brittle BaF2 crystals was investigated. The same predeformation, as has been shown previously, leads to the increasing of the limited plastic deformation of MgO crystals by one order of magnitude. It was found that in both investigated crystals, as in the case of MgO crystals, at the test temperature T2 ≅ 0.1 Tm limited plastic deformation before fracture obviously increases if the specimen was prestrained up to εp ≦ 1% at T1 = 0.5 Tm. This increase is as higher as the plasticity of crystal is lower. In BaF2 crystals it reaches a factor of 20 and more. The effect is connected with the creation of mobile dislocations during the high temperature predeformation and dislocaton sources for subsequent deformation at lower temperatures and with the homogeneity of the process of plastic deformation. These conditions prevent the appearance of dangerous places in which the fracture can begin.
Stress relaxation in the intermetallic phase V3Si at elevated temperatures
Authors: Bertram M. , Paufler P. 
Published: January 2007

AbstractThe plastic deformation behaviour of the intermetallic phase V3Si (Cr3Si‐type) was investigated in stress relaxation experiments. The experiments revealed that V3Si shows stress relaxation after dynamic deformation above 1550 K. The characteristic parameters of stress relaxation depend strongly on temperature, chemical composition (within the range of homogeneity) and deformation rate. The decrease of stress is governed by dislocation climb processes.
Amorphousness of metalloid ion implanted metals as a function of irradiation dose
Authors: Rauschenbach Bernd 
Published: January 2007

AbstractIon implantation into crystalline metals at room temperature an at lower temperatures can result in the formation of amorphous phases. The effect of dependence of amorphization on the implantation dose due to the impact of metalloid ions into metals is described by a model based upon the theory of critical energy density. Comparison is made to experimental results.
Effect of plastic deformation of the thermoluminescence of γ‐irradiated NaCl and KCl Crystals
Authors: Chandra B. P. , Elyas M. , Kathuria S. P. 
Published: January 2007

AbstractThe overall thermoluminescence (TL) intensity of γ‐irradiated NaCl crystals initially increases and then decreases with the number of newly‐created dislocations. However, the overall TL intensity of γ‐irradiated KCl crystals increases with the increasing number of newly created dislocations. The TL spectra are recorded for different plastic deformations at different temperatures. It is found that the plastic deformation has no considerable effect on the TL spectra of γ‐irradiated NaCl and KCl crystals. Trap destruction model and trap competition model are discussed for the decrease in the TL intensity with deformation of the crystals. The physical ideas behind the increases in the relative intensity of glow peaks and the appearance of new glow peaks are explored.
The role of iron ions in YAG and YAP
Authors: Kvapil Josef , Kvapil Jiři , Kubelka J. , Autrata R. 
Published: January 2007

AbstractSpectroscopic properties of YAG and YAP doped with Fe were compared. YAG :Fe crystals grown under reducing atmosphere showed strong colouration whereas similar colouration in YAP :Fe was found after oxygen treatment. Nd3+ luminescence was effectively quenched by Fe ions in YAP, whereas Ce3+ luminescence was quenched by Fe ions in both the materials.
Effect of grinding on the low temperature photoluminescence of certain inorganic crystals
Authors: Chandra B. P. , Majumdar B. 
Published: January 2007

AbstractThe broadening as well as shift in the photoluminescence spectra of K2[Pt(CN)4] · 3 H2O, Ba[Pt(CN)4] · 4 H2O, CdS:Te and Ru(C15H11N3)2I2 · H2O crystals take place with their grinding. The original vibronic peaks at 632 and 628 nm of CdS:Te and Ru(C15H11N3)2I2 · H2O crystals, respectively, disappear with the grinding. A new vibronic peak at 650 nm appears with grinding of Ru(C15H11N3)2I2 · H2O crystals. It is concluded that the change in the photoluminescence spectra is attributed to the creation of dislocations during the process of grinding.
On the computer simulation of many‐beam electron microscopical images of phyllo‐silicates
Authors: Heydenreich J. , Hillebrand R. , Werner P. 
Published: January 2007

AbstractThe polytypism of pyrophyllite as a special phyllo‐silicate is investigated by means of high resolution electron microscopy (HREM), supported by computer simulation. Electron micrographs of appropriate specimen orientations provide crystal structure images, which reveal the actual stacking sequence of the silicate layers. Two crystallographic models (2M1‐ and 1Tc‐type) are applied for the numerical simulation of the image contrast. The process of the electron scattering in the crystal as well as the influence of the imaging parameters are described by means of multi‐slice image calculations. The strong effect of through‐focusing to the image contrast of the silicate structure is pointed out.
Modification of the smectic B phase by the aid of dielectric relaxation
Authors: Kresse H. , Gajewska B. 
Published: January 2007

AbstractThe analysis of the dielectric relaxation data in the liquid crystalline SB phase allow to classify the substances into two groups: SB phases which are similar to the low or high temperature modifications. The experimental results are correlated to the recently discussed „heaxtic”︁ and „solid like”︁ SB modifications.
Influence of gravitation on the processes of heat and mass transfer in solution crystal growth by the travelling heater method (THM) (III)
Authors: Cherepanova T. A. , Apanovich Y. V. 
Published: January 2007

AbstractThe effect of the natural and thermocapillary convection on the vortex configuration in solution during growth of PbTe crystal by the travelling heater method is considered. The estimation of the parameters of growth process (i. e. axial temperature gradients, gravitational acceleration, degree of the solution's surface contact with ampoule), when the vortex configuration undergoes qualitative variation, is given. In terms of the one‐dimensional thermodiffusive problem solution the effect produced by the convective stirring on the position of growing and dissolving interfaces is described.
Dislocation etching of tin iodide single crystals
Authors: Desai C. C. , Rai J. L. 
Published: January 2007

AbstractSingle crystals of tin‐iodide (SnI2) have been grown using the controlled reaction between SnCl2 and KI by diffusion process in gel medium. As grown (010) surfaces of the crystals have been optically studied. Characteristic etch pits have been observed on them. This suggests that SnI2 crystals might go into dissolution in the acid‐set gel. By successively etching (010) surfaces in a mixture of ammonia, acetic acid, and CdCl2 solution, it is established that the pits indicate the site of dislocations in the crystals. This is further confirmed by comparing the etch patterns before and after chemically polishing (010) surfaces. The average dislocation density in the crystals have been evaluated and found to be 3.2 × 103 cm−2 and the implications are discussed.
On the estimation of X‐ray extinction changes due to randomly distributed dislocations in crystals
Authors: Klimanek P. , Hanisch K.‐H. 
Published: January 2007

AbstractA procedure proposed by Ivanov, Klimanek and Skakov for the quantitative estimation of X‐ray extinction in crystals containing randomly distributed dislocations is established without restriction concerning the defect density on the basis of stochastic geometry. The dependence of the extinction coefficient of a X‐ray diffraction peak obtained in this way agrees very well with experimental observations.
Plastic bend in a growing crystal
Authors: Eidelman L. G. 
Published: January 2007

AbstractIn case of nonlinear axial temperature distribution the relaxation of thermoelastic stresses results in the plastic bend of the growing crystal, i. e. in the generation of a residual lattice curvature equal to ϱ b. Based on results from Billig and from Indenbom the author presents estimations of dislocation densities (ϱ) (i. e. residual lattice curvature) taking into account an elastic limit differing from zero. It is shown that sign and value of the residual lattice curvature may be effectively used as criteria pointing out how thermal conditions should be changed for abtaining more perfect crystals. This approach application allowed to grow larger KCl single crystals (300 mm in diameter more than 100 kg by weight) with better structure perfection (specific subboundaries surface 2—3 cm2/cm3, mean subgrain dimension 0.6—1 cm, mean mutual disorientation of subgrains of not more than 6′).
Doping mechanism and properties of Zn‐doped GaN‐epitaxial layers
Authors: Andreev V. M. , Petrov M. N. , Pichugin I. G. 
Published: January 2007

AbstractThe role of oxygen in the process of doping GaN by Zn is established. It is shown theoretically and experimentally that Zn is dissolved in GaN in the form of complexes ZnO when oxygen or water vapour is present in the ambient of the growth reactor. Most of the complexes are neutral. Only the small part of Zn introduced is situated in electrically active positions. This fact can explain the enormously high Zn concentration which is necessary to obtain the compensation of GaN native donors.The electrical and luminescence properties of GaN epitaxial layers doped by Zn are given and the relation of these properties to the growth and doping conditions are considered.
Iso‐epitaxial growth of n‐octacosane crystals
Authors: Prasad P. B. V. , Raju I. V. K. Bhagavan 
Published: January 2007

AbstractIso‐epitaxial(epilayer)growth of n‐octacosane crystals is reported. The morphology of the epilayers is in the form of triangular growth islands with or without truncature. Epilayer growth precedes spiral growth mechanism which occurs at medium and low supersaturations, respectively. The occurrence of triangular and truncated rhombic platelets is found to be a manifestation of growth at medium supersaturations.
Investigations on binary p‐nitrophenol and trichloroacetic acid eutectic system
Authors: Sharma B. L. , Sharma N. K. , Bassi P. S. 
Published: January 2007

Abstractp‐Nitrophenol and trichloroacetic acid eutectic system has been investigated using phase‐diagram, undercooling, linear velocity of crystallization and viscosity measurement methods. Microstructure of the eutectic indicates that it possesses faceted‐faceted (f/f) morphology. Phase equilibrium data have been subjected to thermodynamic analysis, and GE and SE values for each mixture as a function of composition and temperature have been determined. Thermodynamic analysis shows that the system is non‐ideal.
Electrical properties of AgGaSe2 epitaxial layers
Authors: Neumann H. , Nowak E. , Schumann B. , Kühn G. 
Published: January 2007

AbstractEpitaxial layers of AgGaSe2 with thicknesses in the range from 50 to 70 nm were deposited onto (111)A‐oriented semi‐insulating GaAs substrates by flash‐evaporation in the substrate temperature range TS = 825 … 900 K. Films grown at TS ≦ 850 K are n‐type conducting whereas p‐type conductivity was observed at TS ≧ 875 K. In the p‐type samples two acceptor states with ionization energies of 60 and 410 meV were found from an analysis of the electrical measurements.
The effect of temperature on the kinetics of scale growth
Authors: Veverka František , Söhnel Otakar , Hlaváč Michal 
Published: January 2007

AbstractThe temperature dependence of the kinetics of incrustations growth on heat‐exchange surfaces from solutions of NH4NO3 was examined. With increasing temperature the formal kinetic exponent of growth is decreasing and the kinetic constant of growth is increasing. The linear rate of growth of NH4NO3 incrustations is increasing with rising temperature within the whole range of measured supersaturations.
Dielectric investigations in liquid crystalline substances with elongated lateral groups
Authors: Kresse H. , Keil M. , Weissflog W. 
Published: January 2007

AbstractBy the aid of dielectric measurements (dipole moments, static dielectric constants, dielectric absorption) the influence of the chemical structure of a lateral group on the dielectric behaviour has been investigated. From the experimental data can be deduced that the lateral group rotates independently.