bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Transition Energy of the Short Period Basic Polytypes of CdI2
Authors: Khan Momeen M. Y. 
Published: January 2007

AbstractThe CdI2 material grown under similar thermodynamic conditions exhibits several polytypes (phases). Out of these the basic phases are thermodynamically independent and grow with their minimum free (potential) energy. In the present paper we have calculated the Madelung constants cohesive (potential) and the phase transformation energy for the basic phases viz. 2H → 4 H.
Spectrometric Study of the Thermal Evolution of Mechanochemically Prepared Hydroxyapatite‐based Powders
Authors: Krajewski A. , Celotti G. , Ravaglioli A. , Toriyama M. 
Published: January 2007

AbstractThis study deals with the production of hydroxyapatite by a mechanochemical method, especially following the transformations that are involved during their annealing when the physico‐mechanical conditions of synthesis are more or less strong. In particular the higher the reacheable crushing pressure during synthesis, the lower the presence of spurious phosphates during sintering. The main structure‐related parameters were evaluated as a function of annealing temperature, and possible interpretations given thoroughly.
Investigation of a Twisted Phase between the Cholesteric and the Smectic A Phase
Authors: Chanishvili A. , Chilaya G. , Petriashvili G. , Neundorf M. , Pelzl G. 
Published: January 2007

AbstractIn a ternary mixture of two liquid crystals and a non‐mesomorphic chiral dopant an intermediate state with an unusual texture was found between the cholesteric and the SA phase which could be identified as a separate twisted mesophase. The reflection wavelength of this mesophase does not change with temperature whereas the transmission of unpolarized light decreases from 50 to 20%.The experimental findings point to the existence of a twisted grain boundary phase.
Growth of GaAs Crystals by VGF at Different As Source Temperatures
Authors: Frank C. , Hein K. , Hannig C. , Gärtner G. 
Published: January 2007

AbstractThe influence of the As source temperature on the properties of undoped 〈100〉 orientated GaAs crystals during VGF crystal growth was investigated in the range of TAs = 600 to 631 °C. The crystal morphology has shown significant differences. A monocrystalline growth is observed in the range of TAs = 607 to 620 °C. The EPD values are in the range of 103 cm−2 irrespective of the preset temperature of the As source. A decrease in the As source temperature from 620 °C to 607 °C will result in a reduced concentration of the intrinsic defect EL2 from 0.8. 1016 cm−3 to 0.6. 1016 cm−3.Der Einfluß der As Quellentemperatur auf die Eigenschaften von undotierten, <100>‐orientierten GaAs Kristallen bei der VGF Züchtung wurde im Bereich von TAs = 600–631 °C untersucht. Die Kristallmorphologie wies dabei deutliche Unterschiede auf. Bei TAs von 607–620 °C wird einkristallines Wachstum beobachtet. Die EPD Werte liegen dabei im Bereich von 103 cm−2 unabhängig von der eingestellten Temperatur der As‐Quelle. Mit Verringerung der As Quellentemperatur von 620 °C auf 607 °C tritt eine Reduzierung der Konzentration des Eigendefektes EL2 von 0,8. 1016 cm−3 auf 0,6. 1016 cm−3 ein.
Crystallization of K2SO4 in presence of Cr2O Ions
Authors: Nývlt Jaroslav , Žáček Stanislav 
Published: January 2007

AbstractBichromate ions exhibit a strong effect on crystallization of potassium sulphate. Solubilites in the three‐component system given in the literature for 25 and 40 °C were recalculated for the region from 20 to 70 °C and bichromate concentrations up to 10%. Metastable zone width measurements in solutions containing up to 3% of the admixture served for an estimate of the kinetics of nucleation. Batch crystallization experiments and MSMPR experiments yielded kinetic data of nucleation and crystal growth. Computer simulations of the crystal shape indicated the effect of admixture on the crystal growth of individual faces.Die Kristallisation von K2SO4 wird stark durch die Anwesenheit von Cr2O beeinflußt. Die Löslichkeit in diesem Dreikomponentensystem wurde an Hand von Literaturangaben für 25 und 40 °C auf das Intervall 20 bis 70 °C und bis 10% der Beimischung rechnerisch erweitert. Messungen der Breite des metastabilen Gebietes in Lösungen mit einem Gehalt bis 3% der Beimischung dienten zur Bestimmung der Keimbildungskinetik. Diskontinuierliche und kontinuierliche Kristallisationsversuche lieferten kinetische Daten der Keimbildung und des Kristallwachstums. Die Kristalltracht des K2SO4 wurde mit dem Rechner simuliert, was die Abschätzung der Einwirkung der Beimischung auf die Wachstumsgeschwindigkeit einzelner Flächen ermöglicht.
Structure and Texture of Nickel‐Molybdenum Catalysts on Alumina Support Modified with Fluoride or Chloride Ions
Authors: Lewandowski M. , Sarbak Z. 
Published: January 2007

AbstractThe performed study involves measurements of a specific surface area via a BET method, of the pore volume, FT‐IR, and a derivatographic study of a series of Al2O3‐supported nickel‐molybdenum catalysts modified with fluoride and chloride ions. It was found that fluoride ions lead to a decrease in the specific surface area of catalysts, whereas chloride ions have a small effect on this parameter. Modification does not change the type of pores of the catalysts, yet it affects their size and increases concentration of OH groups adsorbed on the surface of the catalysts relative to the carrier and the unmodified catalyst. Addition of fluoride ions decreases the thermal stability of the catalyst, whereas chloride ions does not cause any change.
Doping Properties of Pr2O3 Associate InP Liquid Phase Epitaxy
Authors: Chang Liann‐Be , Liu C. C. , Cheng Y. C. , Chang L. B. 
Published: January 2007

AbstractInP epilayers were grown on semi‐insulating InP substrates by liquid phase epitaxy with Pr2O3‐doping. Most grown layers yield mirror‐like surfaces and good crystal quality. Hall measurements indicate that n‐type background concentration of those grown InP layers will decrease from a value of 2.8 × 1017 to 3.0 × 1016 cm−3. Their correspondent 77 K mobility also varied from a value of 1326 to 3775 cm2/V s. The photoluminescence (PL) spectra of Pr2O3‐doped InP epilayers display narrower FWHM and stronger intensity ratios (for band peak to the impurity peak). These PL spectra also demonstrate that the grown layers exhibit a pure crystal quality.
Carbon‐limited Dissolution of Oxygen in Niobium
Authors: Starikov V. V. , Lykov I. N. 
Published: January 2007

AbstractThis article deals with results of the invsetigations connected with limitation of oxygen dissolution in niobium by means of creating of the carbide protective coating on the niobium surface or forming of the solid solution of carbon in niobium. It is shown that the carbide coating increases essentially the life time of the niobium parts for vacuum equipment and is consumed as a result of interaction with oxygen. The carbon dissolution in niobium does not hinder redox reaction at the Nb(C)/Nb2O5 boundary and causes the conductivity increase of the dielectric film Nb2O5.
Coefficient of Volume Expansion and Thermoacoustic Parameters in Two Natural Oils
Authors: Murthy Y. Narasimha , Murthy V. Rama , Ranga Reddy R. N. V. 
Published: January 2007

AbstractThe Sharma constant S0, the isochoric temperature coefficient of volume expansivity, the isochoric temperature coefficient of internal pressure, the reduced compressibility, the reduced volume and a few other acoustic parameters are evaluated for two Natural Oils namely Mango Kernel fat and Sal Seed fat using only the coefficient of volume expansion. The Sharma constant which was shown by Sharma to be a constant in a number of non‐mesomorphic systems is bound to be a constant in the two oils/fats, studied by the authors with the same character of constant value both in the isotropic and nematic phases with anomalous behaviour and pre‐transitional effects at and in the immediate vicinity of the phase transition temperature. These results are also in conformity with our Ultrasonic results published elsewhere (MURTHY et al.).
Relationship between Crystal Structure and Properties in Substituted Thienyl Chalcones
Authors: Genbo Su , Youping He , Zhengdong Li , Rihong Jang 
Published: January 2007

AbstractFour substituted thienyl chalcone derivatives: 3‐(4‐chlorophenyl)‐1‐(3‐thienyl)‐2‐propen‐1‐one (CTC) (HE Youping et al. 1994), 3‐(4‐bromophenyl)‐1‐(3‐thienyl)‐2‐propen‐1‐one (BTC) (HE Youping, SU Genbo 1995 (b)), 3‐(4‐methylphenyl)‐1‐(3‐thienyl)‐2‐propen‐1‐one (MTC), and 1,3‐Di(2‐thienyl)‐propen‐1‐one ((DiTC*) (LI Zhengdong, SU Genbo) have been synthesized. Analysis of these crystal structures showed to form noncentrosymmetric structure, CTC and BTC crystals belong to the space group P21, MTC belong to Cs, its isomer (MTC*) (HE Youping, SU Genbo 1995(a)) and isomer (diTC*) of DiTC(T‐1) (GOTOH, HAHASHI) were crystallized in the centrosymometric space group P21/n (LI Zhengdong, SU Genbo; HE Youping, SU Genbo 1995(a)). CTC, BTC, and MTC showed high SHG activity 90 to 100 times as large as KDP and also blue light region transparency with a cut‐off wavelength of 400 nm.
The Nature of One‐sided Intergrowths on (001) of Triclinic Centrosymmetric K2Cr2O7 (II)
Authors: Heide G. , Follner H. , Jackson R. A. , Wilde P. J. 
Published: January 2007

AbstractSHUBNIKOV first observed in 1912 that centrosymmetric K2Cr2O7 crystals (P1) exhibit a growth anomaly in highly supersaturated solutions. The (001) faces of these crystals are always smooth, the parallel opposite faces are always rough. Electron micrographs show these rough surfaces to be crystallites that have grown in stacks. In Part I of this publication, the crystallite orientation was determined using electron‐induced diffraction methods. As a rule, these crystallites are parallel intergrowths. Only a small number of crystals near the surface of the host crystal are twinned according to [010]. Part II sought to ascertain the cause of these one‐sided intergrowths. To determine the most favourable energetic arrangement of two intergrown individuals, interactions across the intergrowth face as a function of shifts parallel to (001) and to (001) were calculated, 64 theoretically possible cases were considered. Only in the [010]‐twin and the seldom‐occurring [110]‐twin is an approximation of the 2/m symmetry of the macroscopic twin arrangements also found in the intergrowth structure, and this is the case only when the (001) faces of the host and guest crystal are intergrown.
Gravitational Effects on Mixing and Growth Morphology of an In0.5Ga0.5 System
Authors: Okitsu Kazuhiko , Hayakawa Yasuhiro , Yamaguchi Tomuo , Kumagawa Masashi , Hirata Akira , Fujiwara Syogo , Okano Yasunori , Imaishi Nobuyuki , Yoda Shinichi , Oida Toshihiko 
Published: January 2007

AbstractA mixing experiment of multicomponents melts was performed using a uniform temperature furnace in the Second International Microgravity Laboratories (IML‐2) mission. Growth morphologies and Ga concentration profiles were analyzed for the samples with the compositional ratio of 0.5 In–0.5 Ga–1.0 Sb grown under microgravity and on earth. The sample with free surface grown under microgravity was nearly spherical in shape, except some parts with projections. Ga was dispersed homogeneously in the bulk because the mixing was enhanced by Marangoni convection due to the concentration gradient. On the other hand, the sample grown on earth was a double cylindrical shape with different diameters, and Ga concentration decreased from top to bottom, showing clearly the effect of gravity. Many needle crystals were formed in both space and earth samples due to rapid cooling. The average size of the needle crystals grown in space was larger than that of the earth sample.
Growth Characteristics of Mercuric Iodide Single Crystal
Authors: Li Zhen‐Hui , Li Wei‐Tang , Liu Jun , Zhu Shi‐Fu , Zhao Bei‐Jun , Yin Shu‐Jun , Chen Guan‐Xion , Yuan Hong , Xu Hua‐Peng 
Published: January 2007

AbstractThe HgI2 single crystal with few large smooth faces, high quality and 360 g in weight has been grown by a new technique of modified vapour phase located point method, and the growth characteristics of HgI2 single crystals have been investigated in detail. It is found by means of X‐ray diffraction that the crystals grown with the c‐axis parallel or perpendicular to the pedestal plane have both the prism faces {110}.
X‐ray Investigations of Shape Memory Alloys
Authors: Terziev L. , Bojinov V. 
Published: January 2007

AbstractThe investigation aims to analyse the influence of different kinds of thermal treating on the structure of martensite.Maxima of the X‐value are observed at 60–70 minutes for the sample aged at 200°C and 90 minutes for that aged at 375 °C and minima for Y after almost the same time. We consider that with these results the discussion on the processes occurring during short ageing times will be activated, because in the literature there is lack of such a results.
On the Mixed Crystals Formation in the Fe(Zn) (HCOO)2–Cd(HCOO)2–H2O System
Authors: Vassileva Violeta 
Published: January 2007

AbstractThe solubility in the Fe(HCOO)2–Cd(HCOO)2–H2O and Zn(HCOO)2–Cd(HCOO)2–H2O systems have been studied by the method of physico‐chemical analysis at 25 °C and mixed crystals of the type Fe1‐xCdx(HCOO)2.2 H2O and Zn1‐xCdx (HCOO)2. 2 H2O have been obtained. The lattice parameters of the mixed crystals have been calculated. It has been established that the isostructural Fe(HCOO)2. 2 H2O and Cd(HCOO)2. 2 H2O form isomorphous mixed crystals, whereas the isostructural Zn(HCOO)2. 2 H2O and Cd(HCOO)2. 2 H2O yield isodimorphous mixed crystals. The difference in the behaviour of the two pairs of formate salts has been attributed to the difference in the Me–Om, bond lengths in the coordination octahedra, forming the crystal structures.
Preparation and Characterization of 3‐Acetamide‐4‐N‐Cyclooctylamino‐Nitrobenzene Crystals: A New Organic Material for Nonlinear Optics
Authors: Yanes A. C. , Torres M. E. , Lopez T. , Stockel J. , Peraza J. 
Published: January 2007

AbstractThe preparation, characterization (UV/VIS, IR, Mass, 1HNMR, and 13CNMR‐DEPT, heteronuclear multiple quantum correlation (HMQC), X‐ray diffraction and DSC), measurements of optical second‐harmonic generation SGH and dielectric studies of 3‐acetamide‐4‐N‐cyclooctylamine‐mitrobenzene (ACN), a new organic molecular crystal with potential applications in nonlinear optics are reported.
Quenching by Copper Atoms of the EL2‐induced Luminescence in GaAs
Authors: Glinchuk K. D. , Prokhorovich A. V. , Vorobkalo F. M. 
Published: January 2007

AbstractIt is shown that the introduction of copper atoms into GaAs crystals containing antistructure defects EL2 (isolated arsenic atoms on gallium sites AsGa) leads to a practically complete disappearance of the EL2‐induced luminescence bands peaked at 0.63 and 0.68eV. This effect is connected with the passivation of the EL2 defects (i.e. with the substantial decrease in their concentration) because of their interaction with copper atoms (they become bound by copper atoms) resulting in an appearance of electrically inactive ASGaCUGa complexes.
Detection and Study of Structural Phase Transformations in Cesium Amidosulfonate
Authors: Tzolova Genka , Haussühl Eiken , Budurov Stojan 
Published: January 2007

AbstractThree new structural phase transformations in the Cs amidosulfonate were detected and studied by means of DSC, X‐ray diffraction, infrared spectroscopy and by measuring the temperature dependence of the dielectric constant of monocrystalline platelets. In the temperature range from 325 to 345 K a second‐order phase transition occurs. After completion of the second order‐phase transformation, a first‐order phase transformation proceeds. At higher temperatures (435 K) a lambda‐transition occurs. The transition temperatures, enthalpies and entropies of the above reactions as well the melting temperature and the heat of melting of the CsSO3NH2 were obtained. By means of the methods of H. KISSINGER and T. OZAWA the activation energies of the first order phase transformation were determined.
Calculation of displacement fields and simulation of HRTEM images of dislocations in sphalerite type A(III)B(V) compound semiconductors
Authors: Lazar M. , Wagner G. 
Published: January 2007

AbstractThe displacement fields of different kinds of both perfect and dissociated dislocations have been calculated for an isotropic continuum, and by means of linear elasticity. Additionally, the corresponding HRTEM images have been simulated by the well‐established EMS program package in order to predetermine the structural aspects of dislocations, and then to compare it with experimental HRTEM micrographs. The latter ones resulted from plastically deformed GaP single crystals and InAs/(001)GaAs single epitaxial layers. It could be established that using the simple approach of linear elasticity and isotropy results can be obtained which correspond well to the experimental images. So, the structure of various Shockley partial dislocations bounding a stacking fault can be detected unambiguously. The splitting behaviour of perfect 30° dislocations (separation into a 0° and 60° partial) and 90° dislocations (separation into two 60° partials) both with line direction along 〈112〉, 60° dislocations (separation into 30°/90° and 90°/30° configuration) and screw dislocations (separation into two 30° partials) along 〈110〉 are discussed in the more detail. Moreover, the undissociated sessile Lomer dislocation, glissile 60° dislocation and edge dislocation have been considered too.
Lapping Technique of InP Single Crystal Wafer
Authors: Wei Jiang , Lang Liu Xun 
Published: January 2007

AbstractThe wafer processing of Indium Phosphide (InP) is so important that it is getting more and more attentions. Lapping is a basic step just following the ingot cutting. In this paper, the influences of various processing parameters on the lapped wafer quality and lapping rate have been checked, the double‐crystal X‐ray diffraction results about lapped wafers also were presented here. According to the experimental results, the optimum lapping conditions have been obtained.
Polarizabilities and Related Properties of Azo Benzene Liquid Crystal Compounds
Authors: Murthy Y. Narashimha , Murthy V. Rama , Reddy R. N. V. Ranga 
Published: January 2007

AbstractA novel method, molecular vibration approach is presented and used to evaluate polarizabilities, polarizability anisotropies and diamagnetic susceptabilities of Azo Benzene liquid crystal compound. In this approach vibrational frequencies are used to calculate the force constants, mean amplitude of vibrations and bond polarizabilities. In addition, the variation of order parameter with temperature is also studied. The results are compared and discussed with the literature values.
Investigation of the transport processes in tetramethoxysilane gel by the moiré fringes method
Authors: Krasińska Krystyna R. , Krasiński Mariusz J. 
Published: January 2007

AbstractMoiré fringes method have been used in order to study the mass transport processes in tetramethoxysilane (TMS) gel in respect of crystal growth experiments. Diffusion coefficients of potassium dihydrogen phosphate (KDP) solution and ethanol in pure and soaked TMS gel have been measured.
Infrared Spectroscopic and Thermal Studies of Gel Grown Spherulitic Crystals of Iron Tartrate
Authors: Joseph Sherly , Joshi H. S. , Joshi Mihir J. 
Published: January 2007

AbstractGrowth of spherulitic crystals of iron tartrate by controlled diffusion in sodium metasilicate gels has been described. Infrared spectroscopic, thermogravimetric and elemental analysis have been conducted to characterize the crystals. The results are interpreted and explained.
Stabilization Effect of Zr and Ti Additions on the Ageing Characteristics of Al‐1 wt% Si Alloy Through a Creep Study
Authors: Deaf G. H. , Beshai M. H. N. , El Khalek A. M. Abd , Graiss G. , Kenawy M. A. 
Published: January 2007

AbstractAl‐1 wt% Si and Al‐1 wt% Si‐0.1 wt% Zr–0.1 wt% Ti alloys were used to trace the effect of Zr and Ti additions on the behaviour of the steady state creep. After solid solution treatment specimens of both alloys were aged at 623, 673, 723 and 773 K and creep tests were performed at room temperature by applying stresses of 60.0, 62.4, 64.7 and 67.1 MPa. The results showed a sound stabilization effect of Zr and Ti on the ageing characterstics of binary Al‐1 wt% Si alloy. Values of the applied stress sensitivity parameter, m, obtained were in the range of (20–34) for AlSi alloy and (14–19) for AlSiZrTi alloy. Time to rupture was found to be strongly increased by Zr and Ti additions. The activation energies of the precipitation process involved were found to be 81.9 kJ/mole and 33.7 kJ/mole of the AlSi and AlSiZrTi alloys respectively.
Synthesis and X‐ray Crystal Structure Analysis of CU2(CH3CH2COO)4(OP)2
Authors: Jianmin Li , Huaqiang Zeng , Yanxiong Ke , Quanming Wang , Xintao Wu 
Published: January 2007

AbstractThe complex of [CU(CH3CHCOO)2(OPph)]2has been synthesized and its X‐ray crystal structure determined at room temperature, M = 975.96, tetragonal, space group: 141/a(#88), Dx = 1.39 g/ cm3, The final R is 0.067 for 2087 independent observed reflections with 1 > 3α(I). The molecule has an inversion center on the middle of the CuCu axis. The bond‐length of the CuCu is 2.61/(2) Å. The coordinate polyhedron of Cu corresponds to a tetragonal bipyramid. The angle of CuOP is significantly smaller than that of its adducts [Cu(O2CR)2L]2.
Synthesis, Crystal and Molecular Structure of Cd2(sacch)4(Im)4
Authors: Jianmin Li , Yanxiong Ke , Quanming Wang , Xintao Wu 
Published: January 2007

AbstractThe title compound has been synthesized and its crystal structure determined at room temperature. Cd2(Sacch)4(Im)4 F.W. = 1225.83, monoclinic. Space group: C2/c, Z = 4, a = 20.065(3) Å, b = 11.164(4) Å, c = 20.697(6) Å, β = 94.69(5)°, The coordination polyhedron of Cd(II) correspond to a five‐coordinate trigonal‐bipyramid. In the title complex, two of the saccharin groups act as monodentate ligands. The other two act as bidentate ligands. The two Cd(II) ions are bridged by the two bidentate saccharin groups and the distance is 4.75 Å.
Supersaturation Dependence of Induction Period for Three‐Dimensional Nucleation of Substances from Aqueous Solutions Revisited
Authors: Sangwal K. , Polak W. 
Published: January 2007

AbstractThe available experimental data on the supersaturation dependence of induction period for the nucleation of some compounds crystallizing from solutions are analysed from the standpoint of the classical nucleation theory and the mononuclear and polynuclear models in order to obtain values of interfacial tension and pre‐exponential factor for homogeneous and heterogeneous nucleation. It was found that the contributions of homogeneous and heterogeneous nucleations to the experimental data can be separated by assuming that the nucleation rates due to the two nucleations are additive and that the polynuclear model in combination with the separated contribution of homogeneous nucleation to the induction period gives a satisfactory agreement between theoretical estimates and experimental values of the interfacial tension and the pre‐exponential factor.
Deformation and microhardness studies on natural apophyllite crystals
Authors: Dhar Prithvi Raj , Bamzai Krishen , Kotru P. N. 
Published: January 2007

AbstractMicrohardness testing of three different planes of natural apophyllite crystals is reported. Variation of Vicker's microhardness value Hv with applied load ranging from 10–100 g indicates two distinct regions. In the low load region (10–70 g) Hv increases with load till it attains maximum value and then decreases thereafter. This variation is explained qualitatively in terms of depth of penetration of the indentor. Variation of orientation of the indentor w.r.t. each of the (100) and (111) planes indicates microhardness anisotropy.