bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of growth rate dispersion in industrial crystallizers–A classical approach
Authors: Dey Avijit , Gupta Bhaskar Sen 
Published: January 2007

AbstractThe present work concerns itself with the study of the effects of Growth Rate Dispersion (GRD) in industrial crystallizers. The GRD in crystallizers is described by a model similar to the one describes axial dispersion in near plug flow reactors. From it differential and cumulative equations are developed for crystal population, crystal length, crystal area, and crystal mass. The model results have been compared with the available experimental data of sucrose crystallizer.
Thermal cycling, DLTS, and PEC studies on LEC gallium arsenide
Authors: Santhanaraghavan P. , Sankaranarayanan K. , Arokiaraj J. , Anbukumar S. , Kumar J. , Ramasamy P. 
Published: January 2007

AbstractThis paper discusses the growth of gallium arsenide single crystals using the LEC technique. The Semi‐insulating gallium arsenide was studied. The defect investigations were made by DLTS and etching studies. The variation of deep level concentration along the wafer was estimated using DLTS. The fabrication and efficiency of the PEC Solar cells are also reported.
Mass transport effect within the boundary layers in solution crystal growth: Holographic study of KTP and KDP crystal growth
Authors: Xiling Yu , Youchen Liu , Xuefeng Yue , Yi Sun 
Published: January 2007

AbstractUsing holographic phase‐contrast interferometric microphotography, we have carried out real‐time investigations of the mass transport processes taking place during the high temperature solution growth of KTiOPO4 (KTP) crystal and low‐temperature solution growth of KH2PO4 (KDP) crystal. Our experiments demonstrate that a mere diffusion boundary layer is not existing. The mass transport process within the boundary layers is a result of the coupled effect of diffusion and convection actions, no matter whether it is high‐temperature or low‐temperature solution growth. Under free convection state, the influence of bulk supersaturation on the thickness of solute boundary layer exists in the two different regions. The solute concentration distribution within the layer is an exponential function of the position.
Thermoelectric properties of indium sesquiselenide single crystals
Authors: Nassary M. M. , Nagat A. T. , Hussein S. A. 
Published: January 2007

AbstractSingle crystals of δ‐In2Se3 were prepared in the solid state laboratory at Qena‐Egypt, by means of Bridgman technique. The temperature dependence of the thermal e.m.f. α in the temperature range from 205 K up to 360 K of In2Se3 was studied. The δ‐phase In2Se3 sample appeared to be n‐type. The ratio of the electron and hole mobilities are found to be μn/μp = 1.378. The effective masses of charge carriers are m = 1.3 × 10−30, m = 8.27 × 10−31 kg for holes and electrons, respectively. The diffusion coefficient was estimated to be Dn = 3.37 cm2/s and Dp = 2.45 cm2/s for both electrons and holes, respectively. The mean free time between collision can be deduced to be τn = 70 × 10−16 s and τp = 8 × 10−14 s for both electrons and holes. The diffusion length of the electrons and holes are found to be Ln = 1.5 × 10−7 cm and Lp = 4.4 × 10−7 cm.
Phase diagrams and mixing enthalpies of binary liquid‐crystalline systems exhibiting a semectic A phase
Authors: Ernst S. , Churjusova T. , Sokolova E. , Wiegeleben A. , Hauser A. , Demus D. 
Published: January 2007

AbstractThe induced smectic A phase which appears in binary liquid crystalline systems has been investigated. Phase diagrams, clearing enthalpies, heat capacities and mixing enthalpies of two binary mixtures of a terminal polar component and of a weakly polar one are presented. The influence of the alkyl chain length, steric and EDA‐type interactions on the formation of induced smectic A phase are discussed.
Second neighbours velocities and size of faces in crystal habit
Authors: Prywer Jolanta 
Published: January 2007

AbstractInfluence of growth velocities of first and second neighbours on the presence and size of the face in the crystal habit has been studied. It was established and confirmed that the consecutive neighbour affects the face size only after the disappearance of the previous neighbour. The formula for critical growth velocity governing disappearance of faces has been discussed.
A model for the calculation of the purification efficiency of a solid layer melt crystallization process
Authors: Wangnick K. , Ulrich J. 
Published: January 2007

AbstractMelt crystallization processes are in use as suspension or as solid layer processes. The purification efficiency of such melt crystallization processes can be improved by further purification steps such as sweating and washing. Here a mathematical description of experimental results which come from a solid layer type of crystallization process is considered. The experimental results of the purification efficiencies of each step are described by dimensionless numbers which result from a dimension analysis of the influencing parameters.
Stacking fault formation in NiZn f.c.c. alloys
Authors: Vladkova E. D. , Vassilev G. P. 
Published: January 2007

AbstractX‐ray diffraction study of the fault formation in NiZn alloys is carried out. Approximative analyses are performed in order to distinguish the influences of the dispersity and the microdeformations. Correlation between the X‐ray diffraction data and the free molar Gibbs energy is looked for.
Effect of plasma hydrogenation on the defect properties of CuInSe2single crystals
Authors: Yakushev M. V. , Zegadi A. , Neumann H. , Jones P. A. , Hill A. E. , Pilkington R. D. , Slifkin M. A. , Tomlinson R. D. 
Published: January 2007

AbstractThe defect properties of p‐type CuInSe2single crystals hydrogenated by diffusion from a plasma source are investigated using the Rutherford backscattering/channeling technique and photoacoustic spectroscopy. Plasma hydrogenation is found to produce severe lattice damage, to affect the intrinsic defect equilibrium in the near surface region of the crystals and to create an additional donor. A defect formation model including both defect passivation by hydrogen and damage induced defect creation is proposed to explain the experimental data. The thermal stability of the property modifications is limited to temperatures below about 100 °C.
Extention of the “three partial rates” model to layer growth and composition of the ternary Si1–(x+y)GexBy system
Authors: Kühne H. 
Published: January 2007

AbstractThe previously published “three‐partial rates” model of Si1–xGex layer growth (Kühne 1992) has been extended for describing Si1–(x+y)GexBy ternary systems by taking additionally into account a partial rate of boron and a partial rate of boron‐originated silicon deposition. Silicon deposition from a silane‐germane‐diborane‐helium gas mixture at T = 500°C and Ptotal = 0.2 Torr is clearly enhanced by the presence of germane though to a low degree only, but not by diborane. Germanium partial rate as well as boron partial rate depends linearly on the partial pressure of the respective source gas. For illustration the data published by Murase have been used.
Tribologic properties and crystallization behaviour of filled poly(tetrafluoroethylene) resins
Authors: Dobreva A. , Kopchev P. , Veleva M. 
Published: January 2007

AbstractThe coefficient of friction and wear rate of poly(tetrafluoroethylene) filled with molybdenum disulphide, graphite, lead oxide, and basalt are determined. It is found that basalt decreases the wear rate 2000 times. The degree of crystallinity and other nucleation characteristics are also studied. It is estimated that the nucleation activity of basalt is 0.9. The specific surface energy at the melt/crystal interface is found to be 9 · 10−3 J/m2 and the adhesion energy between poly(tetrafluoroethylene) and basalt is 2 · 103 J/m2.
Zn1−xCdx polytype single crystals with various degree of order
Authors: Gosk J. , Kozielski M. J. 
Published: January 2007

AbstractThe results of X‐ray investigations of the polytype structures formed in solid solutions of Zn1–xCdxSe are presented. For compositions of 0.22 < x < 0.35 polytypes 8H, 6H, 4H, and DS (disordered structure) are present. The Zn1–xCdxS single crystals of 0 ≦ x ≦ 0 were obtained by Bridgman's method under high protective argon pressure from the melt. The structures are characterised by FARKASZ‐JAHNKE statistical parameters π(m,p), and by parameters PLH of the polytype unit cell formation probability.
Study of the evaporation mechanism in silicon carbide crystals growth from vapour phase
Authors: Lilov S. K. 
Published: January 2007

AbstractInvestigation of the thermal etching (evaporation) of the source material in the process of silicon carbide crystal growth from the vapour phase by the sublimation method has been carried out. It has been established that silicon carbide etching in the temperature interval (2200–2600) °C takes place with the formation of whiskers of evaporation. The mechanism of their formation has been examined and the character of the whisker distribution in the charge of the source silicon carbide has been studied.
Remarks on the separation of a solid solution transported by evaporation‐condensation at a small temperature difference
Authors: Szczerbakow Andrzej 
Published: January 2007

AbstractThe nearly congruent transport of a solid solution by incongruent solid‐vapour and vapour‐solid phase transitions in a closed, almost isothermal system is considered–in particular referring to the crystal growth of pseudobinary AIVBVI solid solutions. The fact is interpreted that the small temperature difference required for the creation of the mass driving force of the process causes composition variations smaller than often assumed.
Thermal expansion in the AgGa(S1−xSex)2solid solutions from X‐ray diffraction data
Authors: Orlova N. S. , Kochkarik O. E. , Bodnar I. V. 
Published: January 2007

AbstractThe lattice parametersaandcas well as the axial thermal expansion coefficients in the AgGa(S1‐xSex)2solid solutions with chalcopyrite‐type structure were determined as a function of temperature in the range from 80 to 700 K and compositionxusing an X‐ray powder diffractometry technique. It is found that the thermal expansion coefficients were anisotropic and for all the solid solutions the thermal expansion coefficients along the tetragonalc‐axis were negative whereas those along thea‐axis and the volume coefficients were positive. The directions in which the crystal thickness does not change as temperature varies, were found. The composition dependences of these coefficients were non‐linear.
Physical properties of single crystals of KTiPO4, KxRb1−xTiOPO4 (x = 0.85; 0.75), KGeOPO4 and KTiOAsO4
Authors: Haussühl S. , Luping Shi , Baolin Wang , Jiyang Wang , Liebertz J. , Wostrack A. , Fink Ch. 
Published: January 2007

AbstractSingle crystals of the title compounds of optical quality and dimensions up to 30 × 25 × 25 mm were grown by the flux method. During the growth process the formation of twins consisting of bicrystals was observed, even in the case of single‐crystalline seeds.The twinning boundaries could be detected by etching with hot KOH solutions.The following physical properties were investigated: refractive indices, dielectric constants, thermal expansion, piezoelectric, and electrooptic effects, elastic and thermoelastic constants. The crystals exhibit a quite similar behaviour. The anisotropy of all properties is quasi‐tetragonal.In respect to polar properties only small differences within the mixed crystals KxRb1–xTiOPO4 are found. Replacement of P by As does only slightly affect the polar properties, whereas the replacement of Ti by Ge leads to a drastic reduction of polar effects.
Growth of large doped Bi12SiO20 crystals
Authors: Gospodinov M. , Doshkova D. 
Published: January 2007

AbstractThe conditions for growing Cr‐, Mn‐, Fe‐, Co‐, Ni‐, and Cr + Al‐doped BSO crystals from a stoichiometric melt by the Czochralski method have been the subject of research. A decrease of the absorption coefficient along the growth axis was observed in undoped crystals of 50 mm diameter and 150 mm long, which is indicative of melt stoichiometry change in the course of the growth run. The transmission and reflection spectra of different crystals were measured and the absorption coefficients was determined in the range 0.38–0.70 μm. When Fe dopant concentration exceeds a limit value, the absorption spectrum is blue‐shifted relative to the undoped case and the absorption coefficient decreases. Co, Cr, Mn, and Cr + Al dopants produce a red shift and increase the absorption coefficient. Combined Cr + Al doping shift the absorption spectrum to the blue region as compared to Cr‐only doping with the same Cr concentration.
Aerosol particles from bubblers in metalorganic vapor phase epitaxy
Authors: Deppert K. , Wiedensohler A. 
Published: January 2007

AbstractWe report on aerosol particles generated by bubblers in metalorganic vapour phase epitaxy (MOVPE). A triethylgallium bubbler was investigated in a MOVPE set‐up regarding the generation of aerosol. Our measurements show that aerosol particles are produced, and the production depends on the carrier gas flow bubbling through. The distribution of the particle diameters was measured and was found to range from 10 to 600 nm, with the maximum at about 200 nm. While the number of particles is not negligible the precursor is almost only transported as gas molecules. However, particles could possibly reach the substrate and create defects on the surface.
Investigations of phase relations in the system CaONa2OK2OP2O5
Authors: Schneider M. , Gildenhaar R. , Berger G. 
Published: January 2007

AbstractThe lattice constants of the compound Ca2NaK(PO4)2 have been studied at room temperature using an X‐ray powder diffractometer and also in the temperature range from 20 up to 1000 °C by Guinier‐Lenné‐technology. A hexagonal lattice with the parameters a0 = 5.4367 Å and c0 = 7.3125 Å and a cell volume of 187.18 Å3 has been determined for the high temperature phase, existing from 670 °C upward. At temperatures below 670 °C a superlattice structure is formed by tripling the axis a, a′, and c so that it results in a hexagonal superlattice structure cell with the lattice constants of a0 = 16.311 Å and c0 = 21.939 Å and a cell volume of 5054 Å3.
Some peculiarities of the formation of thallium‐containing phases with perovskite‐like structures
Authors: Kuz'micheva G. M. , Khlybov E. P. , Kochetkov V. N. , Palewski T. , Warchulska J. 
Published: January 2007

AbstractThe authors systematize and analyse their own and described in literature experimental data on the composition and structure of high‐temperature superconductors with thallium‐containing phases. Some peculiarities of the isomorphic replacement and formation of thallium phases having single‐ and double‐layered‐type structure were found. Principles of crystallochemical formation of some phases, and chemical and thermal treatment allowing for their formation are described.
Comparative optical absorption and photoreflectance study of n‐type CuInSe2 single crystals
Authors: Neumann H. , Hörig W. , Jones P. A. , Lippold G. , Sobotta H. , Tomlinson R. D. , Yakushev M. V. 
Published: January 2007

AbstractOptical absorption spectra in the photon energy range from 0.4 to 1.2 eV and photoreflectance spectra in the range of the fundamental edge are measured on n‐type CuInSe2 single crystals. Photoreflectance spectroscopy yields the true gap energy while the near‐edge absorption spectra are dominated by acceptor–to–conduction band transitions, the acceptor ionisation energy being about 80 meV. Based on intrinsic defect chemistry considerations this acceptor is ascribed to copper vacencies.
Application of the selected‐area channelling pattern technique to gypsum
Authors: Girlich I. 
Published: January 2007

AbstractThe applicability of the selected‐area channelling pattern (SACP) technique to gypsum single crystals and to polycrystalline gypsum samples is investigated. Suitable specimen preparation and choice of microscope parameters are proposed. In the case of gypsum single crystals it is observed that after some minutes of prolonged electron irradiation the structure is destroyed, and the pattern can no longer be detected. From a series of SACPs a monoclinic standard map for gypsum covering the pole triangles [100‐101‐311] and [010‐111‐210] is constructed and indexed. Practical problems of the technique occurring in polycrystalline samples are analysed.
Stabilization and destabilization of the SA phase in mixtures of 4‐nitrobenzyl‐2,5‐bis(4‐n‐alkyloxybenzoyloxy)benzoates
Authors: Haddawi S. , Diele S. , Kresse H. , Pelzl G. , Weissflog W. 
Published: January 2007

Abstract4‐Nitrobenzyl‐2,5‐bis(4‐n‐alkyloxybenzoyloxy)benzoates exhibit SA phases which are characterized by an antiparallel packing of the molecules and a partial intercalation of the terminal alkyl chains. In binary systems of selected rod‐like components the SA mixed phase can be stabilized or destabilized depending on the molecular length of the rod‐like molecules. This unusual behaviour is mainly due to steric interaction and can be interpreted by a simple packing model.
The radial selectivity of in‐situ core‐doped crystal rods grown by the double die EFG method
Authors: Rudolph P. , Shimamura K. , Fukuda T. 
Published: January 2007

AbstractThe radial selectivity of in‐situ core‐doped Cr, Nd: LiNbO3 crystal rods, grown by the double die EFG (edge‐defined film fed growth) method, has been investigated. Two crucibles are combined with an outer and inner die for ascending of different doped melts. The critical growth parameters affected by the diffusion depended spreading effect of the dopant within the melt meniscus have been estimated. The first experimental tests show a good agreement with the theoretical prediction. Single crystalline LiNbO3 rods with a length of about 100 mm and an outer diameter of 5 mm consisting of sharp separated inner Cr‐ or Nd‐doped core region with diameters between 1.5 and 4 mm were grown successfully.
Study of the mechanism of low‐temperature DyBa2Cu3O7–x synthesis
Authors: Sokolowski J. , Lasocha W. , Hodorowicz S. 
Published: January 2007

AbstractThe formation of superconducting DyBa2Cu3O7–x was investigated by powder X‐ray method. It was found that when oxides and barium carbonate, or precursors were applied the temperature of formation of the ‘123’ phase is the same, only the reaction rates are different.
Growth studies of YVO4 crystals (II). Changes in YVO‐stoichiometry
Authors: Erdei S. , Johnson G. G. , Ainger F. W. 
Published: January 2007

AbstractIncongruent vanadium oxide vaporization of yttrium orthovanadate (YVO4) melt generates changes in both oxygen and yttrium‐vanadium (YV) stoichiometry. Slightly modified YVO4 or YVO4 + Y8V2O17 phases are formed from continuously changing melt systems depending on their starting compositions. The occurrence of Y8V2O17 in yttrium orthovanadate crystal fibers grown by laser heated pedestal growth (LHPC) technique can be simply eliminated by utilization of suitable V2O5‐excess starting compositions. In contrast, the oxygen‐deficient YVO4–x black phase is an inherently oxygen deficient phase with limited solid solution in the YVO4YVO3 subsystem of Y2O3V2O5V2O3 complex ternary phase diagram close to the congruent YVO4 composition (49.3 mol% V2O5–50.7 mol% Y2O3). The greater oxygen deficiency YVO4–x specimens have smaller lattice parameters as determined from detailed XRD data. Ceramic feed rod and fiber crystal grown from the feed rod with slight yttrium oxide excess starting composition were characterized by electron microprobe analysis. Changes in both YV and oxygen stoichiometry were observed along the fiber, due to double limited solid solution system of three dimensional ternary phase diagram. Consequently, both the presence of Y8V2O17 phase and change of YV stoichiometry over oxygen deficiency cause difficulties for YVO4 crystal growth from yttrium oxide excess melt.
X‐ray study of debye‐waller factors and debye characteristic temperatures in AgGa(S1−xSex)2 solid solutions
Authors: Orlova N. S. , Kochkarik O. E. , Bodnar I. V. 
Published: January 2007

AbstractThe Debye‐Waller factors and Debye characteristic temperatures for two principal crystallographic directions in the AgGaS2–AgGaSe2 solid solutions with chalcopyrite structure were determined by an X‐ray powder diffractometry technique as a function of composition and temperature in the range from 80 to 700 K. The anisotropy of both the dynamical characteristics is shown to exist and the character of anisotropy changes with composition. The composition dependences of the Debye‐Waller factors and Debye temperatures are non‐linear. From the experimental data some thermodynamic properties were calculated and the variation of all investigated dynamical characteristics during anion substitution was analyzed.
Electrical and photoelectrical properties of chalcopyrite n‐AgInS2 crystals
Authors: Opanowicz A. , Kościelniak‐Mucha B. , Vassilev V. 
Published: January 2007

AbstractThe chalcopyrite n‐type crystals have been grown from AgInS2 material having stoichiomtric Ag excess. The temperature dependence of the Hall effect in these crystals have been studied. The ionization energies of donors have been determined. The dependence of the photoconduction on the photon energy, the light intensity and the temperature in the n‐AgInS2 crystals have been measured. The recombination model of photoconductor with one class of recombination centres has been proposed for explanation of the photoelectrical results.
Design of agitated crystallizers
Authors: Nýlvlt Jaroslav 
Published: January 2007

AbstractThe evaluation and/or design method for crystallization, based on the system constant BN, has been applied on crystallization data of various substances published in the literature. A correlation of the BN values with the relative kinetic exponent of crystallization, n/g, demonstrates that the applicability of the method is independent of the size of equipment, mode of crystallization and mode of supersaturation creation.
Porous solids and their characterization methods of investigation and application
Authors: Meyer K. , Lorenz P. , Böhl‐Kuhn B. , Klobes P. 
Published: January 2007

AbstractPorous and finely divided solids are distinguished by a large surface to volume ratio. As a result, they have specific properties, such as enhanced reactivity, a high adsorption capacity, and a lowered sinter temperature.This contribution gives a survey over selected aspects of porous solids, with the main emphasis on methods of characterization and their applications. We treat porous solids with a regular pore network (zeolites) and irregular pore structure (sintered compacts, rocks). After a short review of the possibilities of characterization, we will describe the methods of gas adsorption and Hg intrusion in detail. Furthermore, we will give a critical assessment of the measurement of typical characterization parameters, such as the specific surface area, the pore volume and the pore volume distribution. The fractal character of large‐surface and porous solids and the related uncertainty of the outcomes of measurements result in the necessity of standardization of experimental procedures and in the need for reference materials.The section on applications treats examples of porous solids from different areas: densification of ceramic materials, porous ceramic carriers for flue gas desulfurization, technical catalysts (zeolite/binder), zeolites for the separation of substances, sedimentary and crystalline rocks.
Investigations on triallylthiourea mercury bromide (ATMB) crystal growth
Authors: Hou Wen‐Bo , Xu Dong , Yuan Duo‐Rong , Liu Ming‐Guo , Zhang Nan , Tao Xu‐Tang , Sun Suo‐Ying , Jiang Min‐Hua 
Published: January 2007

AbstractThis paper presents the growth process of a new organometallic nonlinear optical (NLO) crystal triallylthiourea mercury bromide (ATMB). The growth conditions are analyzed in terms of the pH value of solution, and also crack of the crystal is interpreted according to anisotropy of thermal expansion coefficients.