bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational Studies of Bis(thiourea) Cadmium Chloride and Tris(thiourea) Zinc Sulphate Semiorganic Non‐linear Optical Crystals
Authors: Selvasekarapandian S. , Vivekanandan K. , Kolandaivel P. , Gundurao T. K. 
Published: January 2007

AbstractSingle crystals of Bis(thiourea) cadmium chloride (BTCC), and Tris(thiourea) zinc sulphate (TZnS) have been grown from saturated aqueous solution by slow evaporation method at room temperature. The laser Raman and FT‐IR spectra on these crystals are recorded in the frequency range 50–4000 cm−1. The spectral data of BTCC and TZnS are interpreted on the basis of thiourea crystal vibrational data. The vibrational frequencies in the FT‐IR and Raman spectra of BTCC and TZnS establish that ZnSO4 and CdCl2 metal complex are coordinated with thiourea by the metal to sulfur bonds. The effect of the metal complexation on thiourea molecule and nature of bands due to different vibrational modes have been discussed. The lattice vibrational frequencies changes have also been observed and analyzed.
Growth, Characterization and Non‐Critical Phase‐Matching of Niobium‐Doped KTP Crystals
Authors: Jiyang Wang , Yaogang Liu , Jingqian Wei , Minghua Jiang , Zongshu Shao , Wenjun Liu , Shusheng Jiang 
Published: January 2007

AbstractA series of niobium doped KTP (Nb: KTP) crystals has been grown. XRD and DTA experiments show that the Nb: KTP crystal structures do not differ from that of KTP (within experimental error) and that the melting points of the crystals increase with increasing Nb content. Synchrotron radiation topography revealed that the main defects of the crystals were growth sector boundaries, growth striations, inclusions and dislocations. Second harmonic generation experiments were performed using a 12.2% Nb:KTP and the d15 and d24 values of csystal were determined to be (3.7 ± 0.4) and (8.3 ± 0.8) × 10−9 esu, respectively. The relationship between phase‐matching angle and Nb content for a 1.064 μm laser was determined and in the case of a 4.0% Nb:KTP crystal, non‐critical phase matching was realized.
X‐ray Lang Topography and Infrared Spectroscopy in Quartz Crystals Grown Hydrothermally with Intermittent Runs
Authors: Guha A. K. , Annamalai N. , Kar T. , Sengupta S. P. 
Published: January 2007

AbstractGrowth defects in Y‐plates obtained from Y‐bar synthetic quartz crystals, grown hydrothermally with intermittent runs, have been studied for the first time by X‐ray Lang topography and infrared spectroscopy. To study the effect of interfaces on dislocation structures, the growth runs have been discontinued several (6 to 7) times by switching off the autoclaves from 30 min to 1 h. The dislocations were observed to change their directions at the generated interfaces, sometimes they stop at the in terfaces or move straight through the interfaces depending on the angles of the interfaces which are presumably low‐angle grain boundaries. The percentage transmission of infrared beam has also been measured as a function of the distance traversed in the crystal. The inverse anelastic loss (Q) decreases at the interface which is due to the greater accumulation of chemical impurities and H bonded OH− ions at these interfaces. The effect of in‐situ electric field on the topographic contrast has also been studied which reveal some interesting results on account of space charge polarization.
Ti‐adsorption on Se‐prereacted GaAs (110) surfaces studied by SXPS
Authors: Eckardt I. , Schröter T. , Tiedtke K. , Wagner N. 
Published: January 2007

AbstractThis study is embedded in the broader context of reactive metal overlayers and passivation on GaAs. High resolution synchrotron‐radiation photoemission experiments for Ti coverages on Se‐reacted GaAs (110) surfaces show that, contrary to clean Ti‐reacted GaAs (110) interface, there is no initial disruption (submonolayer reaction) of the surface involving both Ga and As atoms during early stage of interface formation. However, a delayed Ti involved reaction appears at a trigger coverage of about 1 ML involving only As atoms from the prereacted AsSe interface configuration continued by Stranski‐Krastanov growth mode. A second reacted phase starts to form two GaTi involved configurations replacing GaSe bonds near a Ti coverage of 4 ML. The preferential chemical trapping of Ti by Se atoms is associated with a smaller interface thickness very likely <10 ML instead of 50 ML in the case of clean Ti/GaAs (110) interface caused by mobile As atoms.
Effect of Neutron Irradiation and Annealing on the Intensity of the Copper Related 1.01 eV Emission Band in n‐type GaAs
Authors: Glinchuk K. D. , Prokhorovich A. V. 
Published: January 2007

AbstractEffect of neutron irradiation (E = 2 MeV, ϕ ≤ 1015 n/cm2) and subsequent annealing (T ≤ 700 °C, t = 30 min) on the intensity of the copper‐related peaked at hvm =1.01 eV emission band in n‐type GaAs (n0 = 2 × 1018 cm−3) is studied. A strong irradiation‐induced increase of the above emission intensity was observed testifying about the irradiation‐stimulated growth in the concentration of copper‐related 1.01 eV radiative centres (CuGaVAs pairs). A model is presented to explain this effect.
Crystal Data, Electrical Resisitivity and Mobility in Cu3In5Se9 and Cu3In5Te9 Single Crystals
Authors: Parlak M. , Erçeleb Ç. , Günal İ. , Özkan H. , Gasanly N. M. , Çulfaz A. 
Published: January 2007

AbstractX‐ray powder diffraction data were obtained for Cu3In5Se9 and Cu3Te9, which were found to crystallize in orthorhombic and tetragonal systems, respectively. The electrical resistivities and Hall mobilities of these compounds were investigated in the temperature range 35–475 K. Cu3In5Se9, was identified to be n‐type with a room temperature resistivity of 3 × 103 Ω·cm which decreases with increasing temperature. For T < 65 K impurity activation energy of 0.03 eV and for T > 350 K onset of intrinsic conduction yielding a band gap energy of 0.99eV were detected. The neutral impurity scattering was found to dominate at low temperatures, while in the high temperature region thermally activated mobility was observed. Cu3In5Te9 exhibits p‐type conduction with a room temperature resistivity of 8.5 × 10−3 Ω·cm decreasing sharply above 400 K and yielding an impurity ionization energy of 0.13 eV. The temperature dependence of mobility indicates the presence of lattice and ionized impuritiy scattering mechanisms above and below 160 K, respectively.
Field induced Increase of Pitch in Planar Cholesteric Liquid Crystals
Authors: Chilaya G. , Hauck G. , Koswig H. D. , Petriashvili G. , Sikharulidze D. 
Published: January 2007

AbstractIn cholesteric liquid crystals the application of an electric field parallel to the helix axis can change the wavelength of selective reflection. For decreasing pitch of the studied mixtures, the colour shift becomes more stable against the field‐induced transformation of the initial Grandjean structure into a confocal texture. In compounds with a low crossover frequency, a field induced increase of the pitch was observed at the switching between low and high frequency fields. The investigations allow new conclusions on the origin of the colour shift.
Characterization of a Flux‐grown NdxY1‐xAl3(BO3)4 Crystal by X‐ray Projection Topography
Authors: Hu X. B. , Jiang S. S. , Wang J. Y. , Huang X. R. , Liu W. J. , Zeng W. , Pan H. F. 
Published: January 2007

AbstractNdxY1‐xAl3(BO3)4 (NYAB) single crystal was grown by the flux method using K2CO3MoO3 as a solvent. By x‐ray projection topography, the defects on a (0001) slice of the NYAB crystal are investigated. It is found that the main grown‐in defects in NYAB crystal are growth bands, growth sector boundaries and inclusions. The formation of defects is discussed and methods to reduce the defects are proposed.
Texture and structure of nickel‐molybdenum catalysts supported on alumina modified with sulfate and phosphate ions
Authors: Lewandowski Marek , Sarbak Zenon 
Published: January 2007

AbstractA series of nickel‐molibdenum catalysts supported on alumina modified with sulfate and phosphate ions was studied. The studies involved texture evaluation measurements through N2 adsorption isotherms. Besides, IR spectroscopic and derivatographic studies were carried out. Results of the studies enable us to conclude that modification of the alumina support with the above ions leads to a significant decrease in its surface area and pore volume. Modification does not result in a change of the type of pores of the support, but in the change of their size dimention. The pores present on the surface of the catalyst have the shape of “ink‐bottles”. Modification with phosphate ions improves the thermal stability of the catalyst, whereas sulfate ions present on the surface of the catalyst undergo decomposition upon heating of the sample. Phosphate ions inhibit formation of aluminum molybdate, and instead form polymeric layer structures of phosphate on the surface of catalysts. Sulfate ions occur in the form of surface aluminum sulfate.
Influence of Rapid Thermal Processing on the Orientation Properties of PbTiO3 Thin Film
Authors: Zhu Jianguo , Xiao Dingquan , Peng Wenbing , Lan Fahua , Wan Deren 
Published: January 2007

AbstractRapid thermal processing (RTP) has developed in fabrication of ferroelectric (FE) thin films because it can reduce processing temperature and time. It also improves the properties of FE thin films compatible with semiconductor devices. The thin film samples used were prepared by a multi‐ion‐beam reactive cosputtering system (MIBRECS) at room temperature. The samples were then subjected to a post‐deposition annealing in a RTP system. It was found that PbTiO3 (PT) thin film can grow on amorphous or polycrystalline interfacial layer and the PT thin films annealed by RTP showed the prefered [110] and [100] textures.
The Crystal and Molecular Structure of 2‐(2′‐Cyano‐2′‐amido‐ethylenyl)‐pyridine
Authors: Öztürk S. , Akkurt M. , İde S. , Kepez M. 
Published: January 2007

AbstractThe title compound (C9H7N3O) has been determined from three dimensional X‐ray diffraction data. The crystals are monoclinic, a = 4.858(3) Å, b = 15.008(7) Å, c = 11.787(2) Å, ß = 94.107(2)°, V= 857.2(4) Å3, z = 4, Dcalc = 1.342 g. cm−3, space group P21/c. The structure was solved by direct methods and refined by full‐matrix least‐squares method (γ MoKα′, R = 0.0766).
The Crystal and Molecular Structure of the Complex Diaquatetrakis(imidazole)copper(II) Terephthalate Crystal Structure Containing Cu(II) Him and TA
Authors: Huaqiang Zeng , Min Yang , Xiaoying Huang , Xueyuan Chen 
Published: January 2007

AbstractThe title compound has been synthesized and its crystals structure determined at room temperature. MW = 536.01, monoclinic, space group C2/c, Z = 4, a = 22.193(5) Å, b = 8.038(2) Å, c = 15.699(4) Å, β = 119.64(2)°. The crystal structure consists of repeated [Cu(Him)4(H2O)2] (Him = imidazole) cations and non‐coordinated terephthalato dianions. The copper(II) ion displays an elongated octahedral coordination being linked to the four nitrogen atoms of the four imidazole ligands and to the two oxygen atoms of the two water molecules. The terephthalato dianions are hydrogen bonded to the four water molecules and four imidazole groups.
Growth of some urinary crystals and studies on inhibitors and promoters. II. X‐ray studies and inhibitory or promotery role of some substances
Authors: Natarajan S. , Rmachandran E. , Suja D. Blisin 
Published: January 2007

AbstractBest conditions were established for the gel growth of three urinary crystals viz., calcium oxalate monohydrate, calcium hydrogen phosphate dihydrate and ammonium magnesium phosphate hexahydrate. The crystals grown were characterized using single crystal X‐ray diffraction techniques and density measurements. Crystal growth experiments were carried out by incorporating the extracts or juices of some natural products in the gel media. By carefully observing the changes in the growth of crystals (compared to control experiments carried out at the same conditions), results about the inhibitory or promotery role of the substance incorporated were obtained. It was found that the extracts or juices of many of the naturally occurring substances have interesting inhibitory or promotery effects. These results may have useful applications in the treatment of recurrent stone patients.
RbxK1‐xTiOPO4 Thin Films Grown on KTiOPO4 Substrates by Liquid Phase Epitaxy
Authors: Shi L. P. , Pun E. Y. B. , Chung P. S. 
Published: January 2007

AbstractThe properties of RbxK1‐xTiOPO4 thin films grown on KTiOPO4 substrates are reported. High quality films were obtained using the flux liquid phase epitaxy method, and optical waveguiding was observed in these epitaxial films. X‐ray analysis shows that the epitaxial films are single crystals films. Their cell constants are different from those of the substrates. The epitaxy growth rate and other film properties were compared for films grown on different faces. Two different surface morphologies were observed for films grown on (100) faces. The morphologies on (201) and (201) faces were also different. The quality of films grown on the (201) face was better. The reason for a structure inversion for films grown on the z− face is discussed.
Diffusion Control during Vapour Crystal Growth
Authors: Nanev Chr. N. 
Published: January 2007

AbstractThe crystal growth rate under diffusion control is considered. Together with nutrient diffusion, the physi‐sorption of an inert gas, which impedes the surface kinetics during vapour growth, is taken into consideration. In this way the size of the diffusion field surrounding vapour grown crystals was estimated. The relations obtained are checked with data for the growth of zinc single crystals in argon atmosphere. The appearance of shallow cavities on their basal faces is used as a morphological mark for growth under diffusion control. Besides, the microstructure of the inner edge of the macroscopically flat periphery, surrounding the shallow cavities is investigated experimentally, by means of SEM.
On the Kinetics of Solid‐Liquid‐Solid. Phase Transformation
Authors: Nývlt Jaroslav 
Published: January 2007

AbstractSolid‐solid phase transformation of different hydrates or polymorphs in suspension proceeds in such a way that the metastable phase dissolves and the stable phase precipitates from the solution. If the starting point lies within the metastable zone of the stable phase, the transformation starts only after elapse of the corresponding induction period. In the case when the starting point is situated outside the metastable zone of the stable solute, the transformation proceeds without any delay. These theoretical considerations are illustrated by an example with recrystallization of calcium sulphate in presence of phosphoric acid; a small concentration change of the acid changes the kinetics significantly.
Viscosity Measurement of La3Ga5SiO14 Melt
Authors: Böttcher Klaus , Shimamura Kiyoshi , Fukuda Tsuguo 
Published: January 2007

AbstractThe viscosity of La3Ga5SiO14 melt was measured by a fixed‐crucible rotor technique in the range between 1520 and 1596 °C. The melt was found to be Newtonian. The viscosity data ranged between 73 and 97 mPa. s, decreasing with increasing temperature. The activation energy of the viscous flow and the volume of a viscous flow unit estimated from the measured data were 90 kJ/mol and 3 × 10−3 nm3, respectively.
Generation of VGaTeAsVAs Complexes in Tellurium‐doped n‐type GaAs by Low‐temperature Annealing
Authors: Glinchuk K. D. , Prokhorovich A. V. 
Published: January 2007

AbstractIt is shown that low‐temperature annealing (T= 425 to 625 °C, t ⩾ 0.5 h) of tellurium‐doped n‐type GaAs crystals (n0 = 2 × 1018 cm−3) leads to a generation of VGaTeAsVAs complexes as a result of a diffusion of arsenic vacancies to VGaTeAs complexes or arsenic and gallium vacancies to isolated tellurium atoms. The observed regularities of generation of VGaTeAsVAs complexes as the annealing temperature and the annealing time are varied are well explained by the proposed model of diffusion‐limited formation of VGaTeAsVAs complexes.
Layer Systems on the Base of Nitrogen‐Doped Tantalum and Niobium with Enhanced Stability
Authors: Fedorenko A. I. , Starikov V. V. , Pozdeev Yu L. , Lykov I. N. 
Published: January 2007

AbstractThere are presented the results of the investigation of tantalum‐ and niobium‐based metal‐oxide bilayers degration in dependence on chemical composition of base metal. Nitrogen dissolved in metal increases stability of chemical composition and electrical properties of oxide films grown on the metal surface by anodic oxidation. This improves reliability and life time of electronic devices containing tantalum‐ or niobium‐based layer systems. The best positive effect of doping tantalum and niobium by nitrogen was achieved after preliminary refining of these metals from oxygen. When nitrogen concentration in the base metal essentialy exceeds its solubility limit at room temperature and nitride phases are formed the dielectrical properties of oxide film get worsen.
Synthesis and Luminescence Characteristics of LiMgAlF6:Ln3+ (Ln = Ce, Eu, Tb)
Authors: Tao Feng , Zhou Xiao‐Jing , Zhu Shi‐Fu , Zhao Bei‐Jun , Hong Guang‐Yan , You Hong‐Peng 
Published: January 2007

AbstractBy solid state reaction, LiMgAlF6 and LiMgAlF6: Ln3+ are synthetized with the ratio 120/100/110 of LiF/MgF2/AlF3, at 1008 K, in high‐purity Ar stream. Their crystal structure which belongs to hexagonal system are determined by X‐Ray‐Diffraction (XRD). Luminescence characteristics of Ce3+, Eu3+, Tb3+ and sensitization of Ce3+ to Tb3+ in LiMgAlF6 are studied. It is shown that the sensitization of Ce3+ to Tb3+ is efficient and a bright green emission is observed.
IR and X‐Ray Powder Diffraction Studies on Ba2Me(HCOO)6. 4 H2O (Me = Co, Ni, Zn)
Authors: Stoilova D. , Koleva V. 
Published: January 2007

AbstractIt has been established that the double salts Ba2Me(HCOO)6. 4 H2O (Me = Co, Ni, Zn) are isostructural with Ba2Cu(HCOO)6. 4 H2O (trinclinic space group P1 = C1i). The infrared spectra of the double salts and their deuterated analogues have been recorded and the internal modes of the formate groups and the water molecules are reported. The analysis of the infrared spectra indicates that some of the internal formate modes (v3 and v4) reflect the existence of three crystallographically independent formate ions. The comparatively large frequency separations between the asymmetric and symmetric C–O stretching modes is a criterion for the different C–O bond lengths within each formate groups. The number and the positions of the bands in the high frequency range (4000–2300 cm−1) are evidence for the existence of two inequivalent water molecules. The apearance of four uncoupled O–D modes in the spectra of the isotopically dilute samples shows that the water molecules are asymmetric. The librational modes of the water molecules are discussed as well.
The Investigation of Relation Between the Transition Temperature and the Unit Cell Volume in (K1‐xCsx)2ZnCl4 Mixed Crystals
Authors: Ahn H. Y. , Jeong H. T. , Jeong S. Y. 
Published: January 2007

AbstractThe relation between the phase transition temperature and unit cell volume in the (K1‐xCsx)2ZnCl4 mixed crystals was studied. The phase transition temperature of A2BX4 family is dependent on the size of cation and anion (FABRY and PEREZ‐MATO). That is, the transition temperature of crystal decreases with increasing unit cell volume. In this study we investigated this property of mixed crystals with the increasing mixture ratio. From the current study, we obtained the result that in the mixed crystals (K1‐xCsx)2ZnCl4, the increase of x induces the increase of unit cell volume, so that TI decreases with increasing unit cell volume. In order to determine the distribution of the substituted Cs+, using the near IR and UV spectrophotometer, we investigated both the band gap energy and the type of transition.
Impurity Striations During Bridgman Growth of InSb
Authors: Potard C. , Dusserre P. , Duffar T. 
Published: January 2007

AbstractInSb single crystals have been grown by the gradient freeze method. Striations close to the seeding interface have been evidenced by X‐ray topography and correlated to temperature and growth rate oscillations. It is shown that these striations are related to light impurity segregations and that a non‐linear process should be taken into account to explain the phenomena.
Theoretical Study of Recrystallization Process of Amorphous Ge Layer Subjected to Pulsed Excimer (XeCl) Laser Radiation
Authors: Klinger D. , Auleytner J. , Z̊ymierska D. 
Published: January 2007

AbstractTransient temperature profiles have been studied theoretically in amorphous germanium thin films on the crystal substrate during heating by a single laser pulse. Computer calculations have been based on the Fourier equation of the heat flow. The calculated threshold value of the energy density for the melting the whole of amorphous layer have been reported for excimer laser radiation.
In situ Observed Twin Formation on ZnSe Crystals Growing by Sublimation
Authors: Schönherr E. , Freiberg M. , Hartmann H. 
Published: January 2007

AbstractZnSe crystals were grown by sublimation in closed ampoules between 1335 K and 1365 K. The growth was observed in situ with a video camera after an abrupt change of the supersaturation. The crystals developed preferably {110} faces. Repeatedly a nucleus was formed in ortho‐twin position on a small {111} face which truncated the corner of three adjacent {110} faces. The repeated twin formation led to a preferred growth into the relevant 〈111〉 direction. The twinning already occurred at a low supercooling of less than 1 K and accelerated the growth distinctly.
A Study of Convection, Striations and Interface Shape in InP Crystals Grown by the Double‐Crucible LEC Technique
Authors: Fornari R. , Gilioli E. , Mignoni G. , Masi M. 
Published: January 2007

AbstractA doublecrucible (DC) Czochralski setup has been used for the pulling of semi‐insulating Fe‐doped InP. The level of the Fe‐doped melt in the growth crucible is replanished with the undoped InP from the reservoir crucible. In this way, since the distribution coefficient of iron is very small (about 0.001), the Fe concentration in the growth crucible is virtually unchanged during the pulling so that the axial Fe concentration is much more uniform than in standard LEC crystals. The use of two concentric crucibles has great implications in terms of convective flows, stability of the melt temperature and interface shape. In this paper we report the results of a study on striations and structural defects in InP grown from a double‐crucible LEC arrangement. A dimensionless relationship for correlating striation features with melt motions is also proposed.
Selected 3d‐Transition Metals in Gallium Antimonide: Vanadium, Titanium and Iron
Authors: Lauer S. , Danilewsky A. N. , Meinhardt J. , Hofmann R. , Dörnen A. , Benz K. W. 
Published: January 2007

Abstract3d‐transition metals are known to produce deep levels in III‐V semiconductors like gallium arsenide or indium phosphide. In this work, gallium antimonide was doped with the most promising candidates vanadium, titanium and iron according to the predictions of the energetic positions of the 3+/2+‐charge transfer levels in the bandgap. For optimum incorporation of dopants several growth methods (travelling heater method THM, Czochralski CZ and liquid phase electroepitaxy LPEE) were used. The grown crystals were characterized by photoluminescence and electrical measurements. No deep levels in the forbidden band were found in the case of vanadium and titanium. Vanadium shows a scavenging effect on unintentional impurities. Titanium tends to form inclusions. In gallium antimonide doped with iron an acceptor was found with an activation energy of 26 meV. The findings support the predictions of Tersoff concerning charge transfer levels.