bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth of 2‐methyl‐4‐nitroaniline (MNA) crystals by the bridgman method
Authors: Fukuda T. , Sano T. , Hosoya S. , Yoon D. H. 
Published: January 2007

AbstractOrganic single crystals of 2‐methyl‐4‐nitroaniline (MNA) up to 3 mm in diameter and 20 mm in length have been successfully grown by the Bridgman method using the purified reagent by sublimation. The crystals are transparent and yellow in colour by controlling the growth conditions. In the spectra of yellow coloured crystals no absorption peak is observed until about 450 nm. Also, the crystals of MNA have the two cleavage planes (311) and (010).
Frequency resolved photoconductivity of bulk CdS single crystals
Authors: Belal A. E. , El‐Mongy A. Abd , El Dosoky N. 
Published: January 2007

AbstractPhotoconductivity measurements in CdS single crystal showed that a.c. photoconductivity decays as ω−s, with s value ‐ {1 + α} for ω > 1/τ and ‐ {1–α} for ω < 1/τ. At low frequency values, recombination might be controlled by monomolecular behaviour. As the frequency increases bimolecular behaviour, in shallow states, dominates. Direct recombination is found to be weak dependent on both the intensity and applied voltage. However when band tail recombination is dominant (at higher frequencies), strong dependence is observed.
Enhanced diffusion of phosphorus at grain boundaries in multicrystalline silicon
Authors: Schimpf K. , Palm J. , Alexander H. 
Published: January 2007

AbstractTwo different methods were applied to examine the diffusion of phosphorus at grain boundaries in silicon. Five solar‐cells processed on multicrystalline silicon were investigated. These cells are distinguished by different materials, diffusion‐temperature, and further preparation. Enhanced diffusion at grain boundaries was observed in two of these cells with both methods. One solar cell also showed enhanced diffusion at dislocations. A correlation of the phosphorus diffusion and an enhanced recombination activity of the grain boundaries of these cells is found.
Structure and optical properties of multilayer X‐ray mirrors for long wave part (3.1–4.4 nm) of “water window”
Authors: Fedorenko A. I. , Kondratenko V. V. , Pershin Yu. P. , Poltseva O. V. , Zubarev E. N. , Balakireva L. L. , Didyk V. V. , Burtsev V. V. 
Published: January 2007

AbstractStructure and optical properties (at λ ‐ 0.154 nm and λ ‐ 3.16 nm) of WTi, WTiN, WSc, and CrSc multilayer X‐ray mirrors for long wave part of “water window”' wavelength range (3.1–4.4 nm) were studied by methods of X‐ray diffractometry and cross‐sectional electron microscopy. The reflectivities at λ ‐ 0.154 nm are increased going from WTiN, CrSc, WTi to WSc multilayers. CrSc mirrors have highest reflectivity and resolution at λ ‐ 3.16 nm. Influence of the ambient atmosphere on optical properties of multilayer mirrors is shown.
EINSTEIN model and modern methods in the statistical theory of crystals
Authors: Zubov V. I. 
Published: January 2007

AbstractA connection between various methods of the atomic theory of crystals and the EINSTEIN model is analyzed. It is pointed out that despite the oversimplified choice of a unique mode of vibrations for all atoms, in many cases it provides better results than the DEBYE model does. What is more, a number of methods of the theory of strongly anharmonic crystals can be considered as extensions of the EINSTEIN model which in its turn, is their limiting case when the anharmonic terms and interatomic correlations are neglected. A comparison between some peculiarities and results of such methods is drawn.
Growth of the organic nonlinear optical material mnba‐Et (4′‐nitrobenzylidene‐3‐ethylcarbonylamino‐4‐methoxyaniline) crystals by the czochralski method
Authors: Yoon D. H. , Hashimoto M. , Fukuda T. 
Published: January 2007

AbstractFor the first time melt growth of the nonlinear optical organic material 4′‐nitrobenzylidene‐3‐ethylcarbonylamino‐4‐methoxyaniline (MNBA‐Et) by the Czochralski (CZ) method has been carried out to achieve single crystals with large diameter. [100] oriented boules having a diameter of 15 mm and maximum height of 15 mm have been prepared. The structural quality of the CZ crystals is comparable to those from solution growth. The colour of the melt and the grown crystal changes from transparent to opaque as a result of using the same melt for multiple growing cycles deteriorating considerably the optical transmittance.
Growth and characterization of photorefractive Bi12TiO20 single crystals
Authors: Prokofiev V. V. , Carvalho J. F. , Andreeta J. P. , Gallo N. J. H. , Hernandes A. C. , Frejlich J. , Freschi A. A. , Garcia P. M. , Maracaiba J. , Kamshilin A. A. , Jaaskelainen T. 
Published: January 2007

AbstractPhotorefractive Bi12TiO20 single crystals of high optical quality were grown in a resistive heating furnace from high temperature nonstoichiometric (10:1) solutions of Bi2O3 and TiO2 at pulling rates 0.3–0.8 mm/h at rotation 20–30 rpm along the <001> and <011> axis. Powder X‐ray analysis, Laue method, and electron‐probe microanalysis were used for characterization. BTO crystals have the bcc structure of sillenite type with a0 = 10.178(8) Å. The chemical composition of the crystals can be written down as Bi12.1 ± 0.2Tio0.96 ± 0.09O20.1. Natural optical activity ρ of BTO crystals is 6.3 ± 0.2 deg/mm at λ = 0.633 μm and 11.9 ± 0.2 deg/mm at λ = 0.5145 μm, optical absorption coefficient α = 0.42 ± 0.04 cm−1 at λ = 0.633 μm and linear electro‐optic coefficient r41 = r52 = r63 = 5.3 pm/V. Fanning effect in the “fiber‐like” BTO sample was studied and double phase conjugation with conversion efficiency up to 8% was observed in a wide range of incidence angles of the pump at λ = 0.633 μm for 2 × 3 mW input light power.
Crystallization of copper sulphate
Authors: Giulietti M. , Derenzo S. , Nývlt J. , Ishida L. K. 
Published: January 2007

AbstractResults of the studies of copper sulphate pentahydrate batch crystallization in the temperature range from 70 down to 30 °C are presented. In some of the experiments, free sulphuric acid has been added. The metastable zone width, nucleation and growth kinetic parameters, as well as the system kinetic constant were determined and compared with the data published in the literature.
Growth of bubble‐free Ti‐doped Al2O3 single crystal by the czochralski method
Authors: Fukuda T. , Okano Y. , Kodama N. , Yamada F. , Hara S. , Yoon D. H. 
Published: January 2007

AbstractThe behaviour of bubble entrapment in Ti‐doped Al2O3 single crystals grown by the Czochralski method was studied from the view point of crystal growth conditions such as the crystal rotation rate and kinds of growth atmosphere. The entrapment of bubbles was not correlated with the shape of solid‐liquid interface dependent on crystal rotation rate. We found that the use fo He atmosphere, instead of the conventional atmosphere such as Ar, suppresses the formation of bubbles.
Analysis of the diameteral response of a czochralski crystal II. The melt temperature — furnace temperature relation
Authors: Sveshtarov P. , Gospodinov M. 
Published: January 2007

AbstractThe paper is the second in a series which presentes results on the small‐signal diametral response of a Czochralski crystal grown in a resistively heated furnace to variations in heater temperature and pull rate. Here it is shown that the small‐signal bulk melt temperature variation is related to the small‐signal furnace temperature variation via a first order linear differential equation.
Anisotropic properties of two nematogenic compounds
Authors: Murthy Dr.T. V. S. Arun , Murthy Prof. Dr. V. R. 
Published: January 2007

AbstractThe diamagnetic susceptibilities and optical polarizabilities of two materials that exhibit nematic liquid crystralline phases in the vicinity of room temperature are reported using a molecular vibration approach and a modified Lippincott δ function potential model. The diamagnetic susceptibilities calculated from polarizabilities are also reported.
Effect of Boron Doping in Bi‐based 2223 Superconductors
Authors: Chandra Sekhar M. , Gopalakrishna B. , Kumar M. M. , Suryanarayana S. V. 
Published: January 2007

AbstractSamples with the stoichiometric composition Bi2−xPbxSr2Ca2Cu3−yByOz (x = 0.3, y = 0.2, 0.25, 0.3, 0.4) ceramics were prepared by a solid state reaction method. The samples were annealed at 850 °C for 100 hours (treatment A), and the other at 850 °C for 200 hours (treatment B). From the X‐ray diffraction data of a ceramic sample it is revealed that all the samples were mixed phases of 2212 and 2223. The variation of the lattice parameters with the dopant level are represented. From the D.C. four‐probe electrical resistivity data it was found that for the samples subjected to treatment B the Tc(0) values were higher than those with treatment A. The A.C. susceptibility data were collected by change in the inductance method. The effect of boron doping on the phase formation and Tc(0) is presented and the volume fraction of the phases estimated from the X‐ray data. The presence of boron in the samples was confirmed by the inductive coupled plasma method. The microstructure of the samples was studied by scanning electron microscopy.
Designing Crystal Morphology by a Simple Approach
Authors: Niehörster S. , Ulrich J. 
Published: January 2007

AbstractIn separation processes containing solids, mostly crystals, the interest in shape modifications of the solids has increased. The idea in it is the necessity to save energy, to achieve specific product requirements, e.g. purities, or to provide downstream processes with better feed material. For an organic crystal a simple way to select a growth inhibitor is presented here, in contrast to the concept of “tailor‐made additives”. The additive selected is structurally different from the host molecule and modifies the habit in a desired manner. The procedure of additive selection involves the analysis of the molecular structure of the crystal to be modified and the orientation of the molecules at the surfaces of the morphological most important faces. Furthermore the problem is discussed if the chosen additive is incorporated into the crystal or not. Results are shown for the system caprolactam/ethanol.
Photoacoustic Spectroscopy of Defect States in Etched and Air‐annealed CuInSe2Single Crystals
Authors: Zegadi A. , Yakushev M. V. , Neumann H. , Slifkin M. A. , Tomlinson R. D. 
Published: January 2007

AbstractPhotoacoustic spectra of cleaved, polished and etched, and air‐annealed n‐type CuInSe2single crystals are measured at different frequencies between 30 and 312 Hz. The spectra related to the bulk of the crystals exhibit five structures due to defects that are also present in p‐type crystals. Polishing and etching as well as subsequent air annealing at 100, 200 and 300 °C reveal rather complex changes of the defect equilibrium in the near‐surface region of the crystals which include both relative concentration changes of existing defects and creation of new defects. The results for polished and etched crystals correspond to trends expected from etching induced local modifications of the composition and structure as revealed by electron spectroscopies and ion channeling. Air annealing is found to affect all existing defects and to create up to five new defects which cannot be explained in terms of the related point defect model proposed by CAHEN and NOUFI.
X‐ray Diffraction Study on MgSeO4. 6 H2O at Elevated Temperatures
Authors: Stoilova D. , Koleva V. 
Published: January 2007

AbstractThe dehydration of MgSeO4. 6 H2O has been studied using an X‐ray powder diffraction method at elevated temperatures. Five different solid phases have been identified in the temperature interval of 20–450 °C: MgSeO4. 6 H2O; MgSeO4. 5 H2O (with a small amount of MgSeO4. 4 H2O), MgSeO4. 2 H2O, amorphous MgSeO4 and crystalline MgSeO4. MgSeO4. 5 H2O crystallizes in the triclinic system with the lattice parameters: a = 6.403(2) Å, b = 10.576(5) Å, c = 6.196(3) Å, α = 98.63(2)°, β = 110.36(2)°, γ = 75.25(3)°, SG P1. MgSeO4. 2 H2O forms orthorhombic crystals with lattice parameters: a = 10.304(1) Å, b = 10.351(9) Å, c = 9.138(9) Å. The crystalline anhydrous magnesium selenate crystallizes in the orthorhombic system with the lattice parameters: a = 4.925(2) Å, b = 9.026(5) Å, c = 6.816(6) Å. Additionally MgSeO4. 4 H2O has been prepared and studied roentgenographically: monoclinic system with the lattice constants: a = 6.064(4) Å, b = 13.773(7) Å, c = 8.062(6) Å, β = 91.82(7)°, SG P21/n. According to expectation the magnesium selenate hydrates are isomorphous with the corresponding magnesium sulphate hydrates.
Thermal Oxidation of ZnS Modifications Sphalerite and Wurtzite
Authors: Schultze D. , Steinike U. , Kussin J. , Kretzschmar U. 
Published: January 2007

AbstractThe oxidation of phase pure ZnS in the wurtzite and sphalerite modification upon heating in an air flow has been studied by simultaneous thermogravimetry‐differential thermal analysis and in‐situ X‐ray diffraction at high temperature (high temperature camera and electron synchrotron).The oxidation of wurtzite starts at higher temperature, ZnO is formed without any detectable side or intermediate products. Sphalerite oxidation starts at lower temperature, ZnSO4 and Zn3O(SO4)2 are formed intermediately in side reactions yielding finally ZnO.
Infrared Spectroscopic, Thermal and Electromagnetic Studies of Zinc Tartrate Single Crystals Grown by the Silica‐Gel Technique
Authors: Lopez T. , Stockel J. , Peraza J. , Torres M. E. , Yanes A. C. 
Published: January 2007

AbstractThe paper reports on the growth of single crystals of zinc tartrate, by reaction of aqueous solutions of tartaric acid (L +) and zinc chloride in silica gels. The grown crystals have been characterized by X‐ray, infrared spectroscopy, qualitative elemental analysis, thermoanalytical techniques, and electromagnetic studies.
Growth and Characterization of LiNbO3: Mg + Ti Monocrystalline Fibers
Authors: Li Heping , Feng Ziliang , Wang Xiu , Wang Liangshen , Jiao Zhifeng , Xu Xiaofei 
Published: January 2007

AbstractLiNbO3 : Mg + Ti monocrystalline fibers with a diameter of 200 – 1000 μm have been successfully grown by the laser‐heated pedestal growth method. The lattice parameters, the dopant Mg‐ and Ti concentrations, and the ferroelectric domain structure of the fibers were determined. The results are compared with those in the large crystals grown by the Czochralski method.
Directional Solidification of AlZn Eutectic in Microgravity Conditions
Authors: Pražák M. , Holeček S. 
Published: January 2007

AbstractThe directional solidification of an AlZn eutectic based on the Bridgman method has been carried out on the Earth and in orbit on the Russian orbital station in microgravity conditions on a ČSK‐1 apparatus developed at the Institute of Physics, Czech Academy of Sciences in Prague.From the conditions of growth — furnace rate 0.1 mm/min, axial temperature gradient in the melt approx. 5 K/cm — the study of the microstructure and the measurements of interlamellar spacing, lamellae thickness α1, hardness HK and the anisotropy of linear thermal expansion it follows, that the microstructure of the specimens prepared in outer space shows an overall lower degree of directionality compared with specimens prepared in analogous terrestrial conditions.
Solid Solutions in the FeNbO4TiO2 System
Authors: Balzer B. , Langbein H. 
Published: January 2007

AbstractThermal decomposition of freeze‐dried complex oxalate precursors allows the synthesis of crystalline phases in the FeNbO4TiO2 system at relatively low temperature. This system shows not only a rutiletype, but also a wolframite‐type solid solution (ss), which exists at lower temperatures. The temperature of the reversible transformation wolframite‐rutile decreases with increasing TiO2 content.
The Crystal and Molecular Structure of an Antidepressant Drug (Isocarboxazid)
Authors: İde S. , Topaçli A. , Bayari S. 
Published: January 2007

AbstractThe crystal arid molecular structure of 5‐methyl‐3‐isoxazole carboxylic acid 2‐benzylhydrazine (isocarboxazid, C12H13N3O2), an antidepressant drug, has been determined by X‐ray diffraction method and IR analysis. The compound crystallizes in the monoclinic space group P21/c, with a = 6.376(1), b = 14.131(1), c = 13.256(1) Å, β = 99.75(1)°. The structure has been solved by using SIR program and refined to R = 0.048. The benzene and isoxazoles rings are not coplanar and have a dihedral angle of 167.7(5)° between their respective planes. Some of the bond lengths and angles found in the molecule are distorted due to π‐electron delocalization and strain. The infrared spectrum of isocarboxazid has been also reported and assignments have been suggested for some characteristic bands. These assignments were confirmed by X‐ray analysis.
Crystallization and Thermoelectric Power of Tl2Te3 Single Crystals
Authors: Gamal G. A. , Nassary M. M. 
Published: January 2007

AbstractThermoelectric power (TEP) of Tl2Te3 was measured in the temperature range from 150 to 480 K. The crystal was found to have a p‐type conductivity throughout the whole range of temperature. The effective masses of holes and electrons were determined at room temperature and found to be m = 1.1 × 10−34 kg and m = 1.72 × 10−35 kg, respectively. Also at the same temperature the mobility μp was found to be 1737.8 cm2/V.s and μn was 3962.2 cm2/V.s. The hole and electron diffusion coefficients were obtained as 44.84 cm2/s, and 102.23 cm2/s. The relaxation times for holes and electrons were calculated and yielded the values τp = 1.19 × 1012 s and τn = 4.25 × 1013 s, respectively.
Effects of Rare‐Earth Ions on the Quality of a Li–Zn Ferrite
Authors: Rezlescu E. , Rezlescu N. , Pasnicu C. , Craus M. L. , Popa P. D. 
Published: January 2007

AbstractEffects of the rare‐earth ions on some properties of a lithium‐zinc ferrite used in high frequency are described. A set of seven compounds with formula Li0.3Zn0.4Fe1.96R0.04O4 where R  Yb, Er, Dy, Tb, Gd, Sm and Ce, were prepared by the classical method. The obtained results reveal that, by introducing a relatively small amount of R2O3 instead of Fe2O3, an important modification of both the structure and the properties can be obtained. Curie point, magnetization, electrical resistivity, density, hardness are affected by these substitutions. The effects of rare‐earth ions were explained both by their partial diffusion in the spinel lattice and by the formation of the crystalline secondary phases on the grain boundaries. Densification of the ceramic is attributable predominantly to the relative shrinkage during sintering.Le travail montre les effets des ions de terre rare sur quelques paramètres d'nne ferrite de LiZn utilisé dans la haute fréquence. Une série des sept compositions avec la formule chimique Li0.3Zn0.4Fe1.96R0.04O4 (R  Yb, Er, Dy, Tb, Gd, Sm et Ce) a été preparée par la méthode classique. Les résultants obtenus montrent que par l'introduction des petites quantités de R2O3 dans le lieu de Fe2O3 une important modification tant de la structure que des propriétés on peut obtenir. La temperature de Curie, l'aimantation, la résistance électrique et densité sont affectés. L'influence des ions de terre rare este expliqué tant par leur partiel diffusion dans la réseau spinel que par leur ségrégation à la surface des cristaux comme phases secondaires. La densification du ferrite est atribué en principal à une relative contraction pendant le frittage.
Spectroscopic and Transport Properties of (NH4)2CuCl4 · 2 H2O Single Crystal
Authors: Narsimlu N. , Sivakumar K. , Sastry G. S. 
Published: January 2007

AbstractElectron paramagnetic resonance (EPR), Optical absorption and Transport properties of (NH4)2CuCl4 2 H2O single crystals have been studied. An anisotropic g tensor was observed with gl = 2.241 and g∥ = 2.081 by EPR method. The spin orbit coupling constant is found to be 540 cm−1. The optical absorption in UV region are characterized by charge transfer band, in the visible and near infrared region at 13,333, 4,480, 4,336, and 3,998 cm−1 attributed to the transitions between the (d‐d) stark energy levels of the copper (II) ion in an extended octahedral crystal field. Dc electrical conductivity measurements with temperature reveal an anisotropic characteristic of a two‐dimensional layered structure, and exhibits two first order structural phase transitions at about 383 K and 413 K. These transitions are attributed to loss of the two water inolecules of hydration and free rotation of NH+4 ion from a state of torsional oscillation.
Lithium Intercalation into the Tetradymite‐type Selenides Sulfides Bi2Se3‐xSx
Authors: Bludská J. , Jakubec I. , Bezdićka P. , Karamazov S. , Lošťák P. 
Published: January 2007

AbstractThe reaction rate of Li intercalation into Bi2Se3−xSx single crystals (x = 0, 0.025 and 0.05) increases with an increasing sulfur content in the crystals. This effect has been explained qualitatively by a change in the bond polarity in the Bi2Se3 due to the substitution of selenium atoms by sulfur atoms. This substitution results in a change in the electron density distribution and thus also in the width of the van der Waals gap between the structural layers, responsible for the course of intercalation. This explanation is supported by a quantum‐chemical calculation of the charges on the atoms of the Bi2Se3−xSx lattice manifesting and increase in the negative charge on Se atoms with an increasing value of x.
A Novel Coordination Structure of Dichromates Bonding to Copper (II): [Cu(bipy)2(Cr2O7)] · 2 H2O
Authors: Jianmin Li , Yanxiong Ke , Quanming Wang , Xintao Wu 
Published: January 2007

AbstractDark‐green multimetal compound crystal [Cu(bipy)2(Cr2O7)]· 2 H2O was obtained from aqueous solution of Cu(NO3)2, K2Cr2O7 and bipyridine. The crystal structure was determined by X‐ray crystallography: triclinic P1, a = 7.716(3) Å, b = 9.656(3) Å, c = 15.517(5)Å, α = 77.41(3)°, β = 81.04(3)°, γ = 82.33(3)°, Z = 2. In this compound, two chromium atoms and a copper atom are linked by two oxo bridges (Cu(II)OCr(VI)OCr(VI)). The copper coordination polyhedron corresponds to a five‐coordinated distorted trigonal bipyramid.
A Structural Study of Aluminate Sodalite Ca8[Al12O24](CrO4)2(CACr)
Authors: Melzer R. , Depmeier W. 
Published: January 2007

AbstractThe structure of the cubic high temperature phase of Ca8[Al12O24] (CrO4)2, CACr, has been determined at 700 K by Rietveld analysis of neutron powder diffraction data. The structure is discussed with respect of those of its homologues. The phase transitions of the title compound have been investigated by means of synchrotron x‐ray powder diffraction and differential thermo analysis. High precision lattice parameters have been determined in the temperature range between 350 and 750 K. Three phase transitions occurring at 610 K, 453 K, and 432 K could be verified. Observed anomalies in the lattice parameters versus temperature might indicate a yet unknown phase transition at about 555 K. This is supported by results of differential thermo analysis.
3D Damage Analysis of Laser‐irradiated Materials inside a Scanning Electron Microscope Using Ion Beam Slope Cutting Technique
Authors: Menzel S. , Hauffe W. , Kadner J. , Wetzig K. 
Published: January 2007

AbstractIn practical use of high temperature materials extreme thermal loads at materials surfaces often occur which can effect a non‐reversible material damage or material failure consequently. These generated damages can be studied using an SEM which is coupled with a pulsed Nd:YAG high power laser. The ion beam slope cutting technique is a very suitable method to produce a highly localized cross section in laser irradiated material. By this the three‐dimensional electron microscopic analysis of the damaged bulk material was possible. For the experiments a combination of ion beam slope cutting and conventional ion etching was used. It enables the high quality of microstructure characterization.