bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gross Dissolution of Natural Rhombohedral‐shaped Calcite in Glacial Acetic Acid
Authors: Sidpara G. R. , Mehta B. J. 
Published: January 2007

AbstractGross dissolution of natural rhombohedral‐shaped calcite crystals in different concentrations of glacial acetic (0.3 to 3.4 M) diluted by distilled water is studied. Activation energy of reaction between calcite crystal and acetic acid is calculated and found constant. The preexponential factor is not constant with different concentrations. Weight loss per unit surface area versus concentration of acetic acid is plotted at various temperatures (30 to 55 °C). It is found that the maximum weight loss per unit surface area occurs with 2.5 M of glacial acetic acid for the above temperature range. The value of the pre‐exponential factor is also maximum at 2.5 M of acetic acid. The maximum weight loss per unit surface area is explained with the help of ionic conductivity and viscosity of the etchant.
Crystal and Molecular Structure of mer‐Co(4‐CH3C5H4N)3(N3)3
Authors: Mautner F. A. 
Published: January 2007

AbstractThe crystal structure of mer‐Co(4‐CH3C5H4N)3(N3)3has been determined by single crystal X‐ray methods at 300 K. The compound crystallizes in the monoclinic space group C 2/c, a = 19.087(6), b = 16.769(4), c = 15.845(4) Å, β = 119.04(2)°, V = 4434(2) Å3, Mr = 464.42. Z = 8, Dx = 1.391 Mgm−3, F(000) = 1920, λ (MoKα) = 0.71069 Å, μ = 0.802 mm−1. The cobalt(III) ions are octahedrally coordinated to three azide groups and to three 4‐methyl‐pyridine molecules to form isolated coordination polyhedra.
The Crystal and Molecular Structure of a Gibberellin A3 Pyrazoline Ester
Authors: Kutschabsky L. , Voigt B. , Adam G. 
Published: January 2007

AbstractThe three‐dimensional structure of the gibberellin A3 pyrazoline ester 1 has been established by X‐ray analysis. The compound crystallizes from acetone/hexane in the orthorhombic space group P 212121 with four molecules in the unit cell of dimensions a = 8.853, b = 9.642, c = 23.307 Å. The final R‐value is 0.038 for 1957 reflections.
Al–SnSe2 Schottky Barrier
Authors: Patel S. S. 
Published: January 2007

AbstractShottky barrier diodes are fabricated on SnSe2 crystal grown by direct vapour transport method. The barrier is produced by thermal evaporation of aluminium on as grown single crystal of SnSe2. The barrier height of Schottky diodes are estimated using current‐voltage characteristics, and activation energy measurement. The barrier height is estimated about 0.49 eV. The implications are discussed.
Rapid Thermal Diffusion of Zinc in GaAs
Authors: Nowak E. , Kühn G. , Morgenstern T. , Schumann B. 
Published: January 2007

AbstractRapid thermal diffusion of zinc into semi‐insulating GaAs from spin‐on silica films was investigated for various temperatures and heating rates with halogen lamps as the heat source. Dependent on the heating rate two types of SIMS profiles were observed. The degree of electrical activation of zinc was different as measured by the Hall effect. In some cases at high zinc concentrations, a ZnGa2O4 film on the GaAs surface was formed.
Lattice Vibrations and Interatomic Forces in AIIB2IIIC4VI Defect‐Chalcopyrite Compounds (I) Keating Model Considerations
Authors: Neumann H. 
Published: January 2007

AbstractThe lattice vibrations of the AIIBIII2CVI4 semiconductors with defect‐chalcopyrite structure are treated in a simplified version of the Keating model considering only interaction with nearest neighbours and assuming that all anions occupy their ideal lattice sites. It is found that in this model the frequencies of the nonpolar and polar modes with highest energy are determined by the properties of the BIII–CVI sublattice alone. The frequencies of all the other optical modes depend not only on the AII–CVI and BIII–CVI interactions but are also influenced by the presence of the ordered array of vacancies. The results obtained are compared with previous model considerations.
Annealing Effects on Photoconductivity Spectra of CuInSe2 Single Crystals
Authors: Slifkin M. A. , Al‐Rahmani A. , Imanieh M. , Tomlinson R. D. , Neumann H. 
Published: January 2007

AbstractPhotoconductivity spectra of as‐grown n‐type and p‐type CuInSe2 single crystals and of crystals annealed under maximum and minimum selenium pressure are measured in the photon energy range hv = 0.75 – 3.0 eV and as a function of temperature in the range T = 80 – 320 K. A model with trapping of minority carriers is used to explain the temperature dependence of the photoconductivity. The trap energies present in the samples depend on their preparation conditions.
On Chemical Kinetics of Silicon Deposition from Silane (VI). The Effect of Wafer Diameter
Authors: Kühne H. , Harnisch H. , Puk P. 
Published: January 2007

AbstractChanging substrate diameter, when depositing poly silicon by decomposition of silane in a hot‐wall tube reactor under LPCVD‐conditions, alters total substrate surface area as well as the distance between wafer periphery and tube wall. From a theoretical point of view both quantities are expected to take an influence on the steepness of axial layer growth decay. Relovant experimental results confirm the theoretical considerations, if an additional effect of flow resistance will be taken into account.
Lattice Constant of AlAs
Authors: Leszczynski M. , Micovic M. , Mendonca C. A. C. , Ciepielewska A. , Ciepielewski P. 
Published: January 2007

AbstractThe value of AlAs lattice constant was established in two ways. First, by extrapolating the results for AlxGa1−xAs LPE (aAlAs = 5.6608 Å) and MBE grown epitaxial layers (aAlAs = 5.6620 ± 0.0001 Å). Second, for AlAs MBE‐grown epitaxial layer (aAlAs = 5.6620 ± 0.0001 Å). The measurements were performed with a high accuracy X‐ray diffractometer and compared with results of photoluminescence measurements.
The Influence of the X‐ray Wavelength on the Behaviour of Polar Kossel Reflections
Authors: Geist V. , Nolze G. 
Published: January 2007

AbstractThe Kossel effect permits a determination of polar directions in non‐centrosymmetrical structures. To identify polar reflections unambiguously, differences — as large as possible — in their fine structures are necessary. These differences considerably depend on both the diffraction geometry and the characteristic X‐ray wavelength applied. The reasons of such behaviour are deliberated upon hereinafter and a good harmony achieved of theoretical predictions and experimental findings.
Electron Spin Resonance of Mn2+ in Hemimorphite
Authors: Vassilikou‐Dova A. B. , Eftaxias K. 
Published: January 2007

AbstractThe Electron Spin Resonance of Mn2+ in natural crystals of hemimorphite was studied at RT, X‐band. No fine structure other than the central M = | + 1/2 〉 ⇆ | −1/2 > transition with allowed (Δm = 0) and forbidden (Δm = ±1) hyperfine transitions were observed.The spectrum was fitted with the spin Hamiltonian parameters g = 2.001, A = −84.6 × 10−4 cm−1. The crystal field parameter D was estimated equal to (8 ± 2) × 10−3 cm−1. The most striking result is the size of the hyperfine splitting constant favoring occupancy of sixfold coordinated sites.
Experimental Determination of f″ for Ga and In From Bijvoet Ratio
Authors: Saravanan R. , Mohanlal S. K. , Chandrasekaran K. S. 
Published: January 2007

AbstractThe imaginary components of the anomalous dispersion correction terms for the heavy atoms gallium and indium, evcaluated from a systematic and precise experimetal measurement of the Bijvoet ratios for the spherically ground single crystals of GaP and InP, are reported. The procedure used is based on the work of Engel and Sturm who refined the crystal structures involving light atoms using anomalous scattering and employed the measured structure factors to evaluate the f″ values of the heavy atoms. In the present work, instead of refining the crystal structure, the structure factors are obtained using a refinement program. The experimentally evaluated f″ values are in very close agreement with the reported theoretical values.
Structure Characterization of EDTA Transition Metal Complexes (II) Study on Ba[Co(HEDTA)H2O]2 · 4H2O
Authors: Yugeng Zhang , Jianmin Li , Jifa Fan 
Published: January 2007

AbstractThe d‐d transition spectrum of Ba[Co(HEDTA)H2O]2 · 4H2O crystal was measured at room temperature and experimental results are explained quantitativley by using the ligand field theory and the radial wave function of non‐free Co(II) ion. The crystal structures and the electronic structures of M/Co‐EDTA (M=Ba, Sr, Ca, Mg) complexes are also discussed.
Stress, Strain, and Symmetry of Pseudomorphically Grown Epitaxial Layers
Authors: Tempel A. , Mäder M. 
Published: January 2007

AbstractThe complete stress and strain tensors and the point symmetry of pseudomorphically grown epitaxial layers are calculated from the epitaxial relationship and the elastic constants of the deposit material. The angle misalignment of crystallographic directions in the deposit due to the strain is also calculated and results are given for the epitaxial systems CaF2/Si(100) and CaF2/Si(111).
Growth and Morphology of Hollow Bi2Te3 Whiskers by Physical Vapour Deposition Method
Authors: Kunjomana A. G. , Mathai Elizabeth 
Published: January 2007

AbstractHollow crystals of bismuth telluride have been grown by the physical vapour deposition (PVD) method. Whisker crystals as long as 10 mm have been grown and were identified by X‐ray analysis. The possible mechanism for the growth of hollow whiskers has also been suggested.
The Distribution Coefficient of Isomorphous Admixtures for KCIKBrH2O, K2SO4(NH4)2SO4H2O and KNO3NH4 NO3H2O Systems at 298 K
Authors: Dejewska B. 
Published: January 2007

AbstractFor the systems KCIKBrH2O, K2SO44‐(NH4)2H2O and KNO3NH4NO3H2 O equilibrium investigations have been performed and the distribution coefficients of isomorphous admixtures have been determined. For each solid solution the changes of the distribution coefficient D, the dependencies between the values of the real and ideal distribution coefficients and the directions of energetic changes in these systems during the co‐crystallization of isomorphous and isodimorphous admixtures have been discussed.
On the Presence of Faces in the Habit of Growing Crystals
Authors: Szurgot M. 
Published: January 2007

AbstractPresence and size of a face in the habit are conditioned by the value of relative growth velocity RA/Rcrit A with respect to the critical growth velocity. It has been established that during the growth of crystals only certain values of relative growth velocities RA/Rcrit A occur. Faces of KBC crystals realize values of RA/Rcrit A between 0 and 2. Unity is the demarcation level below which appearance and above which disappearance of faces takes place. Edges and corners of crystals are places where new faces appear during changes in growth conditions.
The Hydrothermal Synthesis of Petalite Mineral Phases and their Morphological Changing by Increasing of Temperature
Authors: Ghobarkar Habib 
Published: January 2007

AbstractIn this investigation the Petalite minerals were synthesized hydrothermally at different temperatures from a glass with the composition Li2CO3:Al2O3: SiO2 and the relation 1: 1: 8. On that occasion the following mineral phases arised:
at low temperatures (410°C) α‐petalite (unit cell å = 11.737 Å/b̊ = 5.17 Å/c̊ = 7.63 Å, space group P2/a);
At 490 °C α‐petalite was splitted to quartz and an orthorhombic β1‐petalite (unit cell å = 18.24 Å/c̊ = 10.54 Å/c̊ = 10.57 Å, space group PmCn). β1‐petalite could be observated until 1000 °C.
at 560 °C tetragonal β2‐petalite (unit cell å = 7.50 Å/c̊ = 9.07 Å, space group P 43212) in parallel with β1‐petalite;
Behind 750 °C β2‐petalite was not observed.
Behind 900 °C a pseudohexagonal mineral phase developed from β1‐petalite. May be it is possible to indicate this phase as hexagonal (unit cell å = 5.217 Å/c̊ = 5.464 Å, space group P 6222 or P 6422). The author suggests to denote this phase as β3‐petalite.
The Effect of Water on Precipitation from Organic System
Authors: Liszi Dr. I. , Bodor B. 
Published: January 2007

AbstractAn organic compound [(5‐propylthio)‐lH‐(benzimidazol)‐2‐yl‐(carbamic acid‐methyl ester)] was dissolved by conc. HCl in water‐acetone mixtures. The solution was precipitated by NH3‐solution which was diluted with pure water, acetone‐water mixtures and pure acetone, respectively. Acetonewater ratio (weight‐fraction) was the same in the solution‐, and precipitating material when the diluting material was acetone‐water mixture. The NIELSEN homogeneous nucleation theory was applied to determine the interfacial tension, σ, the value of which decreased with increasing the water content in the system. This result agrees well with literature data on the wetting behaviour of organic solid compounds in organic solvent‐water systems.
The Back‐Side Morphology of LPE‐Grown AlGaAs/GaAs/AlGaAs Heterostructures after the Complete Removal of the GaAs Substrate by Selective Etching
Authors: Bolkhovityanov Dr. Yu. B. , Hairi E. H. , Yudaev V. I. 
Published: January 2007

AbstractAs‐grown surfaces of AlGaAs/GaAs/AlGaAs heterostructures were stuck down the glass disks and after that the GaAs substrates were removed completely by selective chemical etching. As a result the back‐surface of the heterostructures became open to light. The influence of different factors on the back‐surface planarity and on the density of such specific defects as holes in the GaAs layer have been investigated. It is shown that the density of holes can be decreased to a value less than 1 hole/cm2 if a glove‐box maintained under a pure N2 atmosphere and connected with LPE installation is used.
Effect of Sintering Temperature on Thermoelectric Power of Mixed LithiumZinc Ferrites
Authors: Ravinder D. 
Published: January 2007

AbstractThermoelectric power of polycrystalline lithium‐zinc ferrites having the compositional formula Li0.5−x/2ZnxFe2.0−x/2O4 (where × = 0.2, 0.4, 0.6, 0.8, and 1.0), sintered at 1200, 1250 and, 1300°C has been investigated over the temperature range 300 to 450 K by the probe method. The Seebeck coefficient (Q) is found to decrease with increasing sintering temperature, whereas the carrier concentration (n) and the charge carrier mobility (μ) are found to increase with increasing sintering temperature. Among all the mixed lithium‐zinc ferrites, the one having a zinc content of 0.6 mole has a minimum value of Seebeck coefficient and maximum value of charge carrier concentration.
Material Characterization of Chemically Deposited Photoconducting CdS Films
Authors: Bhushan S. , Sharma S. K. 
Published: January 2007

AbstractResults of SEM, XRD and absorption measurements were obtained to characterize the chemically deposited undoped and rare earth doped CdS films. SEM studies present the crystalline nature of undoped CdS. In Presence of NaF layered growth takes place which finally results in cabbage type growth. In presence of rare earths cabbage and crystalline growth are observed. XRD studies of undoped CdS show combination of cubic as well as hexagonal phases. Presence of impurities results in change in itensity of peaks along with appearance of some new peaks. The absorption coefficient studies show a band gap of 2.41 eV for undoped CdS.
Lattice Variation and Stability of NaClKCI Mixed Crystals Grown from Aqueous Solutions
Authors: Shajan X. Sahaya , Sivaraman K. , Mahadevan C. , Sekharam D. Chandra 
Published: January 2007

AbstractAn attempt to improve the stability of NaClKCl mixed system was made by adding KBr to it. Crystals were grown by the slow evaporation method and characterized by X‐ray diffraction measurements. A large improvement in stability was observed with crystals grown from (NaCl)x (KCl)0.9−x(KBr)0.1 than from NaxK1−xCl solutions.
Carry‐over ‐ A Fundamental Problem in the MOVPE Growth of Heterostructures
Authors: Keller B. P. , Brühl H. G. , Seifert W. 
Published: January 2007

AbstractWe have investigated the MOVPE growth of GaAs, GaP, and InP using TMGa‐TMN (trimethylgallium‐trimethylamine), TMIn‐TMN (trimethylindium‐trimethylamine) and the hydrides arsine and phosphine in reactor cells covered with products of preceding deposition processes. By measurements of the misfit Δa/a we find that besides arsenic also gallium and at higher growth temperatures even indium can be transferred from the predepositions into the epilayer. The mobilization of gallium is possible due to alkyl exchange reactions with indium‐methyl‐species. Indium is most probably mobilized due to its high vapour pressure at high growth temperatures. The extent of carry‐over is limited within a range of a few percent impurity concentration.
Formation Volume of Schottky Defects (Vacancies) in Inorganic and Organic Compounds and the Defect Formation Mechanism of Melting
Authors: Bollmann W. 
Published: January 2007

AbstractThe formation volumeVsof Schottky defects is given byVs= (hs/L) ΔVfwithhs= 8L(formation enthalpyhsof Schottky defects and heatLof fusion given in same units; ΔVf= change of volume due to melting). If there are phase transitions within the solid,Land ΔVfmust be replaced by (L+ ΔHt) and by (ΔVf+ ΔVt), respectively (Dr.Htand ΔVtrefer to the heat(s) of transition(s) and to the volume change(s) due to transition(s), resp.). The pressure dependence of the melting point isdTm/dp= (TmVs)/hs. Independent on the sign ofVsany increase of the Schottky defect (vacancy) concentration above the maximum concentration possible within the solid decreases the melting point thus resulting in the observed surface melting. The melting point is fixed by the characteristics of Schottky defect formation (hs,ss,Vs) and by the bulk modulus of the solid (ss= formation entropy of Schottky defects).
Effects of Group III Cation Substitution in the Raman Spectra of Some Defective Chalcopyrites
Authors: Attolini G. , Bini S. , Lottici P. P. , Razzetti C. 
Published: January 2007

AbstractWe report on the Raman spectra of CdIn2Se4 and ZnIn2Se4 obtained in a transparency region. These spectra have a disordered‐like appearance at high frequencies. A comparison is made with the Raman and IR spectra of the similar compounds CdGa2Se4 and ZnGa2Se4. The overall vibrational behaviour is mainly determined by the anion and a correspondence may be observed between the frequencies of some high energy polar modes. A strong non‐polar breathing mode is observed at nearly the same frequency in all these compounds. The observed similarities between the spectra are discussed within the frame of the existing simplified models.
Study on the Phase equilibrium in the Systems Sodium Selenate — Cadmium Selenate — Water and Sodium Selenate — Manganese Selenate — Water at 25 °C
Authors: Oykova T. , Mihov D. 
Published: January 2007

AbstractThe phase equilibrium in the systems Na2SeO4CdSeO4H2O and Na2SeO4MnSeO4H2O were studied and it was established that new phases were obtained — double salts with a composition: Na2Cd(SeO4)2 · 2 H2O and Na2Mn(SeO4)2 · 2 H2O. The fields of phase equilibrium of the double salts in the triple systems were determined. The composition of the new phases and the number of the water molecules of crystallization were investigated, respectively by the Schreinemackers' method of physico‐chemical analysis and thermogravimetrical analysis. An X‐ray diffraction analysis of the new phases obtained was done.
Catalyzed Nucleation of Poly (Vinyl Chloride)
Authors: Dobreva A. , Gantcheva T. , Gutzow I. 
Published: January 2007

AbstractMicroscopically visible crystallization in a typical non‐crystallizing organic polymer ‐ poly(vinyl chloride) (PVC) is achieved by dissoloving it in an appropriate solvent (cyclohexanone) and inducing the nucleation by introducing various insolube crystallization cores ‐ microcrystals of noble metals (Au, Pd, Pt, Rh, Ir, Ru, Os). It is established that the higher the melting temperature of the metal the higher its activity as a crystallization core in the heterogeneous nucleation of PVC.The reverse process‐oriented crystallization of a foreign substance ‐ NaCl crystals on PVC films is also demonstrated. This result gives an indication of precrystalline structures in seemingly amorphous PVC films.
Study on the Course of Crystallization of Gallosilicate with MFI Structure
Authors: Tuan V. A. , Fricke R. , Jänchen J. , Kosslick H. 
Published: January 2007

AbstractThe kinetics of nucleation and crystallization of zeolite Ga‐ZSM‐5 crystallized in the system 15 Na2O * xGa2O3 * 100 SiO2 * 13 TPABr * 4400 H2O is investigated. The course of crystallization is followed by different methods: XRD, MIR, TG‐DTA, n‐hexane adsorption. NH3‐TPD and pH‐measurement.The low apparent activation energies of nucleation En = 42.5 KJ/mole and crystallization Ec = 20.4 KJ/mole show that the incorporation of gallium into the framework of the zeolite is not as difficult as expected from the disruptive nature of this process. Other synthesis parameters, e.g. temperature, alkalinity and gel composition have a major influence on the crystallization process. Here the nucleation is pronounced influenced whereas the crystal growth is only marginally influenced.The physico‐chemical characterization proves the formation of „reactive”︁ and catalytic active gallosilicate species already in the gel, which are assumed to take part directly in the crystal growth process.
Infrared Lattice Vibrations of TI3AsS4
Authors: Neumann H. , Sobotta H. , Riede V. , Kamba S. , Syrbu N. N. , Golovei M. I. 
Published: January 2007

AbstractInfrared reflectivity spectra of TI3AsS4 single crystals are measured at room temperature in the wavenumber range from 30 to 4000 cm−1 for the polarization directions E‖ c and E ‖ a. An analysis of the spectra with the Kramers‐Kronig method reveals 10 infrared active modes for each of the polarization directions. On the basis of theoretical estimates the modes due to TI‐S and As–S bond vibrations are identified.
Influence of Enhanced Gravitation on the Growth of Ammonium Oxalate Monohydrate Crystals from Aqueous Solutions
Authors: Mielniczek E. , Jakubczyk M. , Sangwal K. 
Published: January 2007

AbstractThe growth behaviour of ammonium oxalate monohydrate crystals on seeds from aqueous solutions under terrestrial and enhanced gravity conditions has been investigated. It was found that all types of faces on the crystals revealed growth layers on them. The faces of the crystals obtained under both terrestrial and enhanced gravity conditions on seeds hung on nylon threads show cracks, trapped inclusions and macrospirals, while the faces of the crystals grown on seeds in fixed holders under enhanced gravity conditions are devoid of cracks, inclusions and macrospirals.
Deformation Induced Micro‐Twins in CdTe?
Authors: Wwinkler M. , Schenk M. , Hähnert I. 
Published: January 2007

AbstractRoom‐ and high‐temperature micro‐indentation experiments have been performed to answer the question if, concerning a material with very low stacking‐fault energy like CdTe, deformation induced twinning occurs in these substances during or shortly after growth.Micro‐twins appear in consequence of room‐temperature deformation only, whereas microindentation at 565°C does not produce any twins, but leads to widely expanded dislocation glide‐figures, due to dislocation climbing and/or cross‐gliding.
A Study of Diffusion by High‐temperature Electron Probe Microanalysis
Authors: Gorfu P. , Blasek G. , Däbritz S. 
Published: January 2007

AbstractThe diffusion between a thin layer and an underlying substrate, with the formation of an intermetallic phase, was studied by electron probe microanalysis (EPMA) measurements with a simultaneous heating of the sample (High‐temperature EPMA ≡ HT‐EPMA). A thin‐film EPMA model calculating the thicknesses and compositions of two thin layers on a substrate (WALDO) was used. A new method with some necessary assumptions has been developed for determining the phase growth coefficients of intermetallic phases from HT‐EPMA measurements by iteratively comparing the measured and calculated X‐ray intensities. Results from the binary system of CuSn are in good agreement with others achieved by different methods reported in the literature. Differences in the case of the binary system of CuIn are discussed.