bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleation of Cracks in CdS during Ultrasonic Treatment
Authors: Bušujeva G. V. , Gricaenko I. G. , Zinenkova G. M. , Klimm D. , Paufler P. , Tjapunina N. A. 
Published: January 2007

AbstractHigh amplitude ultrasonic vibrations with frequencies fr ∼ 90 kHz and vibration amplitudes ε ⩽ 3.4. 10−4 were used to obtain oscillatory stresses σ ⩽ 14 MPa in CdS single crystals. Such treatment leads to the nucleation of cracks in annealed samples and to the formation of dislocations in as‐grown samples. The different behaviour can be explained by the reduction of the free dislocation segment lengths due to the diffusion of point defects towards the dislocation lines during the annealing treatment.
Detection of Side‐Products on Heavy Metal Loaded Zeolites of Type A (PbNaA Zeolite) (II)
Authors: Steinike U. , Jancke K. , Schreier E. , Staedler Chr. , Lutz W. 
Published: January 2007

AbstractDuring the loading of aluminosilicate zeolites type A with heavy metal cations by ion exchange, hydroxides precipitate as permanent side‐products. Even smallest amounts of these surface deposits change the properties of the zeolite drastically, when transformed into a semiconductor composite. Their formation is detectable during the exchange process by means of in‐situ pH measurements. For zinc loaded zeolite A the detection succeeds also by means of XRD measurements. A change of the framework symmetry of zeolite A is observed under the influence of the framework adapted zinc oxide. A change of the framework symmetry from Fm‐3c to Fm‐3m is detected for lead loaded A zeolites, however, it is caused by hydrated lead cations.
Structural Phase Transitions in Zinc(II) Perchlorate Hexahydrate
Authors: Borzęcka‐prokop B. , Hodorowicz S. A. 
Published: January 2007

AbstractPhase transitions in zinc perchlorate hexahydrate are studied by X‐ray powder diffraction method. Structural changes in the vicinity of transitions detected at 364.5 K and 256.3 K are characterized. At the former the orthorhombic Pmn21 phase transforms into the Pmna one (a = 7.812(1), b = 13.518(3) and c = 5.279(1) Å at 348.6 K). The latter involves changes of the orthorhombic unit cell (a = 7.7922(9), b = 13.537(2) and c = 5.0588(6) Å at 251.0 K). Temperature dependence of lattice parameters in the range of 180 to 363.3 K are presented.
Chiral Etch Pits on Sodium Chlorate Crystals
Authors: Szurgot Marian 
Published: January 2007

AbstractMicrotopography of {100}, {110}, {111}, and {210} surfaces of sodium chlorate crystals etched in various solvents has been studied by optical microscopy. It has been established that etch pits formed on left‐ and right‐handed crystals are chiral, and directions of dissolution steps reveal bond chains of the structure.
On Some Transition Metal Complexes Having Orientational Properties(II). Copper(II) complexes
Authors: Frunza S. , Frunza L. , Stoenescu D. N. , Moldovan R. , Beica T. 
Published: January 2007

AbstractAlignment layers containing copper(II) complexes with acrylic acid or polyvinylpyrrolidone show homeotropic orientational properties. This behaviour is supposed to be due to the particular structure of the complex copper(II) ions. We give spectroscopic arguments to support the anchoring of liquid crystal (LC) molecules by coordination to the copper ion within the alignment layer.
Crystallization Kinetics of NaCl in Multicomponent Solutions
Authors: Offermann H. , Von Brachel G. , Al‐Sabbagh A. , Farelo F. 
Published: January 2007

AbstractExperimental results of solubility and growth kinetics measurements of sodium chloride crystals in multicomponent systems at 303 K are given. The effect of several solutes in elevated concentrations on the growth and dissolution kinetics is analysed on volume diffusion and surface integration steps: While the diffusion of ions within the solution decreases by the presence of foreign ions, the integration resistance can increase (mobile or immobile adsorption of foreign ions) or may even be reduced in some cases (due to a decreased surface energy).
Suitable Stress Waveforms for the Deformation‐Induced Electronic Excitation in Crystals
Authors: Chandra B. P. , Rahangdale Yuvraj , Khare P. K. , Bisen D. P. , Sharma Deepti 
Published: January 2007

AbstractA quantum mechanical approach is made to the deformation‐induced electronic excitation in crystals. The ML intensity is assumed to be related to the transition probability P(m, n) from nth to mth state, and it may be expressed as IML = βP(m, n) where P(m, n) = 4π2/hα2 |σmn (ωmn)|2 ·(n · μ)mn·2. It is shown that the ML excitation can take place only by the time‐dependent applied stress. The ML excitation probability is analysed for different waveforms of the applied stress such as constant stress, δ‐function, rectangular stress, single sided and double sided exponential stress, unit step function, external sinusoidal signals cos ω0t and sin ω0t, external exponential function, a periodic function and the stress of sequence of equidistant impulses of unit strength separated by a particular time. It is found that when the stress is a δ‐function, a rectangular waveform, sinusoidal singals cos ω0t and sin ω0t or a sequence of equidistant impulses of unit strength and separated by a particular time, then there is a considerable probability of electronic excitation by the resonance transfer mechanism between the Fourier transform of the stress waveform and the frequency of the emitting electronic system i.e. (E2 – E1)/h.
DC Conductivity and Dielectric Properties of Nano‐particles of Red Mercuric Iodide
Authors: Thomas Binny , Abdulkhadar M. 
Published: January 2007

AbstractDC conductivity and dielectric properties of consolidated nano‐particles of red‐HgI2 have been studied. DC and AC conductivities have been found to be about 3 orders of magnitude larger than that reported for single crystals of red‐HgI2. The enhancement in dielectric properties have been attributed to the defect structure of the particles due to excess surface stress and the structural anomaly of their surface.
Studies of the Growth Habits of the AgGaSe2 Single Crystal
Authors: Zhu Shi‐Fu , Liu Jun , Zhao Bei‐Jun , Jiang Hong‐An , Li Zheng‐Hui 
Published: January 2007

AbstractHigh quality AgGaSe2 single crystals with 20 mm in diameter and 55 mm in length have been grown by the modified Bridgman technique and the growth habits of AgGaSe2 single crystals have been investigated in detail. It is found that the shape of the growth ampoule affects greatly the nucleation and the growth of AgGaSe2 single crystal. A new cleavage face (101) and the natural faces are observed in the as‐grown crystals. For some cases, the growing direction is normal to the (316) face.
Crystal and Molecular structure of 3,3‐Diethyl–2,4,6–[1 H,3 H,5 H] Pyrimidine Trione
Authors: Sambyal Vinod Singh , Goswami K. N. , Khajuria Ravi Kant 
Published: January 2007

AbstractC8H12O3N2, Mr = 184.19, Trigonal, R3 (hexagonal axes) a = b = 26.800(1) Å, c = 6.828(3) Å, α = β = 90°, γ = 120°, V = 4247.11 Å3, Z = 18, Dm = 1.297 Mg m−3, Dc = 1.296 Mg m−3, mu = 0.79 mm−1, F(000) = 1764, T = 293 K, final R = 0.080 for 1205 observed reflections. There are two crystallographically independent molecules in the unit cell of the title compound.
Positron Lifetime and Defects in Y‐doped (Ba0.6Sr0.4)TiO3 Ceramics
Authors: Tang C. Q. , Zhang D. M. , Xue Q. Z. 
Published: January 2007

AbstractThe positron lifetime spectra in Y‐doped (Ba0.6Sr0.4)TiO3 ceramics have been measured at room temperature for Y contents of 0–0.8 at. %. It was found from the experiments that with increasing Y content, the variation of the positron lifetime parameters is nonmonotonic, and the Y content corresponding to the knee is about 0.7 at. %, which is much larger than the La content corresponding to the knee in the La‐doped BaTiO2 (TANG 1994a). The experimental results show that the Y ions substitute predominantly for Sr ions, and this substitution induces a large number of Sr vacancies; when the Y content increases to about 0.7 at. %, the Y ions begin to substitute for Ba ions, and then the associated defects (2 YBaV“SrSr) and (2 YSrV”BaBa) form gradually.
Optical Absorption Spectrum of Co2+ Ion Impurities in Lithium Sodium Potassium Sulphate Single Crystal
Authors: Kumar R. Rama , Reddy Prof. Dr. B. C. Venkata 
Published: January 2007

AbstractOptical absorption spectrum of Co2+ ions doped in lithium sodium potassium sulphate single crystal has been studied at room and liquid nitrogen temperatures. The observed bands are assigned as transitions from the ground 4T1g(F) to various excited quartet and doublet levels of Co2+ ion in octahedral symmetry. The splitting in one of the bands at liquid nitrogen temperature has been explained as due to spin‐orbit interaction. All the observed band positions have been fitted with the parameters B, C, Dq and ζ.
Hardness of Crystals with NaCl Structure and the Significance of the GILMAN‐CHIN Parameter
Authors: Sirdeshmukh D. B. , Subhadra K. G. , Kishan Rao K. , Thirmal Rao T. 
Published: January 2007

AbstractThe microhardness of PbTe, PbSe, EuS and EuSe has been determined. The microhardness vs lattice constant plot for chalcogenides is a curve similar to the one for alkali halides. The Gilman‐Chin parameter (H/C44) has been calculated for a large number of crytals with NaCl structure. There is no unique value representing the entire group of crystals, the values ranging from 0.01 to 0.20.The Gilman‐Chin parameter broadly correlates with the effective ionic charge (e) indicating that it is a measure of the ionicity. Empirically, it is observed that the product (H/C44) · (e)2 is approximately constant.
Investigation of Thermoelectric Power of Ga2Se3 Monocrystals
Authors: Gamal G. A. , Elshaikh H. A. 
Published: January 2007

AbstractSingle crystals of Ga2Se3 were prepared by a technique based on the Bridgman method. Thermoelectric power was investigated in the temperature range 160–525 K. From this investigation many physical parameters such as effective masses of charge carriers, carrier mobilities, diffusion length, diffusion coefficient, and the relaxation time for both majority and minority carriers were estimated. In conjunction with the electrical conductivity and the charge carrier concentration, the thermoelectric power is discussed.
Growth of Semiinsulating GaAs Crystals by Vertical Gradient Freeze Technique
Authors: Frank C. , Hein K. 
Published: January 2007

AbstractGaAs crystals having dislocation densities of 1–2 103 cm−2 were grown using VGF technique. In the grown crystals SiGa is the dominant donor and CAs the dominant acceptor. Theoretical and experimental investigations have shown the possibilities to influence on the silicon and carbon content in GaAs. Based on these results, semiinsulating properties in the crystals could be achieved reproducibly.
Electric and Dielectric Evaluation of KDP
Authors: Parmar S. G. , Chaudhari S. K. , Arora S. K. 
Published: January 2007

AbstractSingle crystals of potassium dihydrogen phosphate, KH2PO4 (KDP), grown by isothermal evaporation at room temperature have been characterized by their measurement of electrical conductivity and dielectric behaviour. Implications in respect of practical utility of KDP crystals in devices have been given.
Dual action of Impurities in Crystal Growth from Solutions
Authors: Alexandru Horia V. 
Published: January 2007

AbstractA dual action of impurities becomes evidently in growth kinetic of prismatic faces of KDP. At higher supersaturation two‐dimensional nucleation mechanism due to impurities prevails. At smaller supersaturation the blocking effect of the steps created by the dislocation mechanism of growth become efficient. The limit of the “dead” growth zone depending on the impurity's concentration and the solution pH is a result of this last effect and agrees with the Cabrera‐Vermilyea mechanism.
Crystal Structure of 5,7‐Dimethoxy‐8‐(2‐oxo‐3‐methylbutyl)‐2 H‐1‐benzopyran‐2‐one (Isosibiricin)
Authors: Singh Attar , Gupta Vivek K. , Rajnikant  , Goswami K. N. 
Published: January 2007

AbstractThe title compound, C16H18O5, a simple coumarin crystallizes in the monoclinic space group P21/c with unit cell parameters a = 7.321(3), b = 21.111(9), c = 11.649(3) Å; β = 123.14(2)°. The structure has been solved by direct methods. The coumarin ring system is planar. The methoxy groups at C5 and C7 are almost coplanar with the coumarin mean plane. The crystal structure is stabilized by C–H… O hydrogen bonds.
Crystal Growth and Differential Thermal Analysis of AgGaSe2
Authors: Zhu Shi‐Fu , Liu Jun , Zhao Bei‐Jun , Jiang Hong‐An , Li Zheng‐Hui 
Published: January 2007

AbstractHigh quality AgGaSe2 single crystals with 20 mm in diameter and 55 mm in length have been grown by Bridgman technique. It is found that there is a second phase of Ag‐rich Ga2Se3 (or named AgGa7Se11) in the AgGaSe2 crystal. It is concluded by discussions with the DTA results and the phase diagram that single crystals grown from polycrystalline materials with stoichiometric composition must contain a second phase of Ag‐rich Ga2Se3. This result is helpful for the heat treatment, in which what and how much is added and what temperature is chosen for the heat treatment, are very important.
A New Molecular Crystal: Urea Tartrate
Authors: Fanqing Meng , Mengkai Lü , Hong Zeng 
Published: January 2007

AbstractUrea tartrate, CO(NH2)2(+)C4H6O6 (hereafter abbraviated as UT) is reported for the first time. Large Single Crystals have been grown by the cooling method from aqueous solution. Some of its physical properties have been measured. The second harmonic generation of powder specimens is about three times larger than that of KH2PO4.
X‐Ray Study of the Structure and Thermal Properties of Ba1–xKxBiO3 at Different Temperatures
Authors: Barilo S. N. , Olekhnovich N. M. , Orlova N. S. , Pushkarev A. V. , Salak A. N. , Shiryaev S. V. 
Published: January 2007

AbstractThe crystal structure as well as the temperature and composition dependences of the lattice parameters, the thermal expansion coefficients in the high‐temperature superconducting Ba1–xBiO3 system were determined by an X‐ray powder diffraction method at temperatures between 80 and 650 K. The character of variation of intensity, profiles, and line widths of the diffraction lines for different perovskite structures as a function of the content x and temperatures was found. The correlation between the behaviour of the thermal expansion coefficients and potassium content was revealed at different temperatures. It is shown that the thermal expansion coefficients vary inversely with rising x at any temperature in the range from 80 to 400 K.
Discontinuous Dielectric Reorientation in the Smectic C Phase of 3‐n‐Heptyl‐6‐[4‐n‐hexyloxyphenyl]‐1,2,4,5‐tetrazine
Authors: Camara K. , Pelzl G. , Schiller P. 
Published: January 2007

AbstractIn the nematic phase and smectic C phase of 3‐n‐Heptyl‐6‐[4‐n‐hexyloxyphenyl]‐ 1,2,4,5‐tetrazine the Freedericksz transition was studied. In both phases the threshold voltage and the switching times were measured. In the smectic C phase two thresholds were observed which can be explained by an asymmetric chevron structure.
Long‐term Crystal Growth under Microgravity during the EURECA‐1 Mission (II) THM Growth of Sulphur‐doped InP
Authors: Danilewsky A. N. , Meinhardt J. , Benz K. W. 
Published: January 2007

AbstractLong‐term crystal growth experiments were successfully performed under microgravity conditions during the first flight of the unmanned EURECA‐1 mission in the automatic mirror furnace (AMF). Two crystals of sulphur‐doped InP with [001] and [111] orientation respectively were grown from indium solution by the travelling heater method (THM). The absence of time dependent buoyancy‐driven convection is documented by the lack of type I striations in the space‐grown crystals. The sulphur concentration is measured by spatially resolved photoluminescence. As expected, the macrosegregation can be described by a pure diffusion‐controlled model which is in good agreement with the findings from the first German spacelab mission D1. Compared to the earth‐grown reference samples, both of the space‐grown InP crystals show strong disturbances such as inclusions and type II striations. The morphological instabilities are similar to growth disturbances already known from the space‐grown MD‐ELI‐01 from the D1 mission.
X‐ray Photoelectron Spectroscopic Studies of Sellinite and Eulytite BGO and BSO Crystals
Authors: Gopalakrishnan R. , Gopinath C. S. , Ramasamy P. 
Published: January 2007

AbstractSingle crystals of Bi12GeO20, Bi12SiO20, Bi4Ge3O12, and Bi4Si3O12 are grown by Floating zone and Czochralski techniques. The X‐ray photoelectron spectroscopic (XPS) studies have been carried out on BSO and BGO crystals. XPS is employed to characterise the surface quality and bulk nature of the crystals. The surface contamination on both types of crystals are identified. In addition to the contamination, some amount of Bi atoms are observed with Bi ions on sellinite. It is demonstrated that the eulytite crystals are chemically more robust to degradation than the sellinite crystals. The predominant covalent and ionic character of Bi4Ge3O12 and Bi4Si3O12 respectively is explained from their oxygen 1s core level spectra.
Effect of Supersaturation and Temperature on the Growth Morphology of Ammonium Oxalate Monohydrate Crystals Obtained from Aqueous Solutions
Authors: Sangwal K. , Zdyb A. , Chocyk D. , Mielniczek‐Brzóska E. 
Published: January 2007

AbstractThe experimental results of a study of the effect of supersaturation and temperature on the growth morphology of ammonium oxalate monohydrate [(NH4)2C2O4H2O; AO] single crystals obtained from aqueous solutions at 30 and 40 °C and supersaturation up to 9% are presented. The observations are analysed in terms of theoretical morphology, growth models and attachment energy for growth units in steps of growing faces.
Tetrabutylphosphonium Cation as Template in the Kinetics of Crystallisation of ZSM‐5
Authors: Lingappan N. , Krishnasamy V. 
Published: January 2007

AbstractZeolite ZSM‐5 was synthesised using ethyl silicate ester 40 and sodium aluminate so as to get the gel mix with SiO4/Al2O3 = 90 employing TBPCl and TPABr templates separately (for comparison) at temperatures 423 K, 448 K, and 473 K. Nucleation and crystallisation processes were kinetically analysed. Activation energies for nucelation and crystallisation and the geometric factors have been evaluated. Correlations were found between the kinetic characteristics and the habits of the crystals formed. The study of the composition and morphology of the intermediates, with the support of SEM pictures, reveal the different mechanisms operating in the templating action of TBPCl and TPABr molecules.
Crystal Structure of an Adduct of Sarcosine with Sulfuric Acid (at 140 K)
Authors: Mostad A. , Natarajan S. 
Published: January 2007

AbstractThe crystal structure of an adduct of sarcosine with sulfuric acid, (C3NO2H8)2SO2−4, has been determined at low temperature (140 K). The crystals are triclinic, space group = P1 with the unit cell dimensions, a= 7.623(1) Å, b = 11.538(2) Å, c = 14.214(2) Å, α = 71.46(2)°, β = 74.36(2)°, γ = 86.46(2)°. Based on 4924 reflections with intensities larger than 3σ(I), the structure was refined to a conventional R factor of 0.038 giving e.s.d.s. in bond lengths and angles of 0.003 Å and 0.2°, respectively. There are two formula units in the asymmetric unit and both sulfate ions exist in two disordered orientations. The sulfate group 1 occupies the two orientations in the proportion 0.82/0.18 and sulfate group 2 in proportion 0.69/0.31. Both Orientations of the sulfate groups satisfy the hydrogen bonding scheme equally well.There is also a pseudo‐symmetry element within the asymmetric unit as one half of this unit is transformcd into the other by a translation of approximately one half along the b‐ and c‐axes. Thus, sarcosine molecule 1 is translated to sarcosine IV and sarcosine II to III. In the same manner, the sulfate group I in its main orientation is translated to the sulfate group 2 in its alternative orientation and vice versa.
Photorefraction Dependent on Composition in LiNbO3 Crystals with and without MgO Doping
Authors: Kan S. , Sakamoto M. , Okano Y. , Yoon D. H. , Fukuda T. , Oguri O. , Sasaki T. 
Published: January 2007

AbstractThe photorefraction in LiNbO3 single crystals dependent on the melt composition with and without MgO doping was investigated. It was found that 1 mol% MgO‐doped crystal with nearly stoichiometric composition has a strong photorefraction resistance. compared with a congruent composition. In an undoped crystal, the photorefraction was shown to be pronounced as incrcasing Li content of a melt from 48.6 to 58 mol% Li2O. These results were discussed from a viewpoint of the relationship between the photoconductivity and the concentration of cation‐site vacancies or Nb on Li‐site.
Photoacoustic Spectra of Complexes of Erbium (III) with Glycine and Alanine
Authors: Qingde Su , Yuetao Yang , Guiwen Zhao 
Published: January 2007

AbstractThe crystals of the complexes Er(Gly)3Cl3. 3 H2O and Er(Ala)3Cl3. 3 H2O were synthesized and the photoacoustic (PA) spectra in the 300–800 nm region are reported. Their PA and absorption spectra are interpreted. The PA relative intensities represented by intensity branching vectors and the perturbation of ligands on the energy levels of Er3+ ion are discussed. The fluorescene properties of Er(Gly)3Cl3. 3 H2O and the relaxation process models were also studied based on the PA and absorption spectra.
The Effective Temperature of Surfaces of Liquid Metals and Some Non‐Metals
Authors: Vlasov A. D. 
Published: January 2007

AbstractAn estimation of decrease of atomic bond energy by raising temperature for surfaces of liquid metals and some non‐metals had been made. The calculation values of the derivative dusdub where us and ub, are bond energy of atoms in surface and bulk of a liquid, are significantly above 1 and in limits from 2 to 10. It was supposed that this results from anomalously intensive thermal expansion of surface layers of liquids – the effect which is well known for crystal surfaces. This expansion was explained by the effective temperature of these surfaces which, thus, was found to be by several times above those for bulk of liquids.
Modelling of Growth Rate for MSMPR Crystallizer Data
Authors: Mydlarz Jerzy 
Published: January 2007

AbstractOne of the most important applications of the population balance approach to MSMPR crystallizer modelling is the recovery of crystal nucleation and growth rates data from steady‐state crystal size distributions (RANDOLPH, LARSON). A large number of studies have confirmed that both size‐dependent (growth rate is a function of crystal size) and growth rate dispersion (crystals of the same size do not have the same growth rate), causes nonlinearities which limit the usefulness of the RANDOLPH and LARSON approach.A discussion of modelling of crystal growth kinetics for simulated and real MSMPR crystallizer data is presented. In the former case, both linear and non‐linear log population density distributions are used. The modelling of growth kinetics is done twice – once assuming that growth rate dispersion is a source of curvature in the log population density vs size data plot and, again when this curvature is caused by size‐dependent growth. Calculations clearly indicate that even for crystallizing systems which follow the McCabe's δL law, both growth rate dispersion and size‐dependent growth models lead to proper estimation of growth kinetics. When log population density vs size data plots exhibit curvature, however, use of the size‐dependent growth rate approach gives more reliable growth kinetics across a broad crystal size range than those obtained from modelling of growth kinetics by growth rate dispersion.