bluuebunny/crossref_metadata_2025 huggingface dataset:
The superposition of the lattice radiation and reflectivity spectra of MoO3 and PbMoO4 crystals
Authors: Syrbu N. N. , Stamov I. G.
Published: January 2007

The Raman scattering of MoO3 at 300 and 77 K and the infrared reflectivity spectra of MoO3 at 300 K have been investigated in different scattering geometries. The Raman spectra of PbMoO4 crystals at 77 K have been investigated also. The reflectivity spectra of MoO3 crystals were calculated for E ∥ c and E ∥ a. The phonon parameters and the effective ionic charges of anions and cations for MoO3 and PbMoO4 crystals are determined. The diagrams of the splitting of the vibrational levels by the Davydov resonance and by the factor group interactions have been determined. It is shown that the lattice radiation of crystals which have a number of vibrational oscillators (MoO3, PbMoO4) begins at low energy vibrational modes and at low values of the damping parameters.
Growth of GaAs from Ga solution under reduced gravity during the D2‐mission
Authors: Danilewsky A. N. , Nagel G. , Benz K. W.
Published: January 2007

Tellurium‐doped GaAs was grown under reduced gravity during the Second German Spacelab‐Mission D2. The growth experiment MD‐ELI‐TRABE is described and first results are presented.
Fast growth of optical nonlinear crystals of 4‐aminobenzophenone from the melt. A candidate for blue light output
Authors: Pan S. K.
Published: January 2007

The Kyropoulos method was used to grow non‐linear optical (NLO) organic crystals of 4‐aminobenzophenone (ABP) from the melt. Growth conditions were discussed. The entropy of fusion of ABP material is 6.75. The crystals had a large effect of frequency doubling.
Growth of lanthanum heptamolybdate crystals by gel technique
Authors: Bhat Sushma , Kotru P. N.
Published: January 2007

The growth of single crystals of lanthanum heptamolybdate is achieved by allowing controlled diffusion of La ions through silica gel using the system La(NO3)3MoO3NH4OHHNO3–Na2SiO3. The reaction mechanism leading to the growth is reported. Mechanism of crystallization of La heptamolybdate is discussed. Formation of Liesegang rings consisting of La heptamolybdate crystals in the system is reported. It is observed that concentration programming and seeded growth enhances the size of crystals. The crystals grown in the system are single crystal platelets exhibiting squarish or octagonal facets. Some crystals exhibit a spherulitic morphology.
Simulation of dopant zone‐leveling for variable distribution coefficient in KCl: EuCl2 system
Authors: Cywiński R. , Damm J. Z.
Published: January 2007

Experimental data of Eu2+ distribution in EuCl2‐doped KCl ingots are analyzed. After settling the relation between variable distribution coefficient and the dopant concentration in the melt, the simulation of the dopant zone‐leveling for various molten zone widths is performed. It is shown that owing to the decrease of the distribution coefficient caused by increasing dopant concentration in the molten zone, the number of the zone passes after which the dopant concentration levels off undergoes significant reduction.
Crystal and molecular structure of 2.2′‐dihydroxyazobenzene
Authors: Schilde U. , Hefele H. , Ludwig E. , Uhlemann E.
Published: January 2007

C12H10N2O2; monoclinic, space group P1 21/c 1 (Z = 2), 826 observed independent reflexions, R = 0.043; lattice dimensions at 25 °C, a = 975.8(3) pm, b = 466.8(1) pm, c = 1186.8(2) pm, β = 108.51(1)°.
A possible new approach to the better understanding of crystallization kinetics
Authors: Stávek J. , Ulrich J.
Published: January 2007

Literature data dealing with the structure of solutions, solubility of tiny particles, and the organization of small colloidal particles in solutions were summarized to support the evidence that the growth units in the crystallization by precipitation are identical with clusters or primary particles. These growth units may self‐organize themselves in a kind of a three‐dimensional network surrounding the growing crystals or secondary particles. This colloidal concept was used to explain qualitatively some experimental facts observed in the controlled double jet precipitation of sparingly soluble salts.
ASL model for prediction of CSD in a continuous crystallizer
Authors: Dey Avijit , Gupta Bhaskar Sen
Published: January 2007

A Monte Carlo simulation scheme is proposed for crystal size distribution (CSD) in a continuous crystallizer for size dependent growth rate. Crystal growth rates are described by Abegg, Stevens, and Larson (ASL) model. The proposed model is used to predict CSD from potassium carbonate crystallizer. The agreement between theory and available data confirms the validity of the model.
The effect of the in‐situ sublimation in the growth of HgI2 platelets from vapour
Authors: Serrano M. D. , Santos M. T. , Diéguez E. , Toubektsis S. N. , Daviti M. F. , Polychroniadis E. K.
Published: January 2007

The Quality of HgI2 platelets grown from the vapour phase has been studied, varying different growth parameters, i.e. starting material, addition of polyethylene, source/crystallisation temperature, in‐situ sublimation. It has been found that the in‐situ sublimation at high temperature is the essential factor for the production of HgI2 platelets. This in‐situ sublimation was made in the same growth ampoule at temperatures over 200 °C and prior to the growth process. All the other growth parameters studied in this work influenced the quality of the platelets although they did not affect their production. Finally, the grown platelets have been characterised by optical observation and by differential scanning calorimetry.
Solidification behaviour of binary organic eutectic alloys
Authors: Rai U. S. , Shekhar H.
Published: January 2007

The phase diagrams of binary organic faceted‐faceted systems of p‐dibromobenzene with acenaphthene, p‐chloronitrobenzene and acetanilide show the formation of a simple eutectic with 0.53, 0.61, and 0.64 mole fraction of p‐dibromobenzene, respectively. Crystallization data, determined by the capillary method, suggest that the eutectics of p‐dibromobenzene with acenaphthene and p‐chloronitrobenzene solidify with alternate nucleation mechanism and the crystallization of the eutectic of p‐dibromobenzene‐acetanilide system takes place by the side‐by‐side growth of the phases involved. With a view to throw light on the thermodynamic behaviour of eutectic alloys of non‐metals, heats of fusion of their transparent organic analogues and their eutectics were determined, and using these values different thermodynamic parameters were calculated. The microstructures of the eutectics show their typical characteristic features.
Anomalous dispersion correction terms of As and Sb
Authors: Saravanan R. , Mohanlal S. K.
Published: January 2007

In our earlier paper (Saravanan et al.), we have evaluated the imaginary part of the anomalous disperison correction term f″ of Ga and In from the measured structure factors of GaP and InP, where one of te atoms (P) is relatively lighter than the other. In the present work the f″ values of As and Sb have been evaluated using the experimental structure factors of GaAs and InSb (where both the atoms are equally heavy) adopting the same principle used in our earlier work. Though both atoms in GaAs and InSb are heavy, this method gives satisfactory results.
To the new theory of crystal strength
Authors: Vlasov A. D.
Published: January 2007

The main conceptions of the non‐dislocation theory of crystal strength have been proposed. These are the thermal stress, the temperature coefficient of thermal stress, and the initial microstrain ϵin at which the thermal stresses start. These conceptions made possible an explanation of the crystal lattice mechanical instability that is well known from strength tests. A new simple form of Morse potential, a relation for the thermal stress, and a way to find the temperature coefficient in this relation have been advanced. Some measurements of very high and of common practice strengths of crystals were compared with theoretical suppositions and calculations.
Dielectric studies on sodium fluoroantimonate single crystals
Authors: Charles J. Benet , Gnanam F. D.
Published: January 2007

Dielectric properties of grown single crystals of Na2SbF5 and Na3Sb2F9 have been carried out. The values of the dielectric constant of Na2SbF5 and Na3Sb2F9 are about 24.1 and 14.3, respectively, at temperatures from 30 °C to 250 °C and 225 °C for 100 kHz.
Debye characteristic temperature of some silver‐base binary alloys
Authors: Bhikshamaiah G. , Sadanandam J. , Suryanarayana S. V.
Published: January 2007

The Debye characteristic temperature (θ) of eight silver base binary alloys in the cubic phase having various compositions have been calculated making use of four different averaging methods from the data on elastic constants. The values of θ are also evaluated from series expansion method. The results obtained were examined in terms of solute concentration, reciprocal of the lattice parameter, mass, electron to atom ratio, and elastic anisotropy. Important conclusions are made.
On the nature of growth hillocks on sodium chlorate crystals
Authors: Szurgot Jadwiga , Szurgot Marian
Published: January 2007

Optical examination of as‐grown {100} surfaces of sodium chlorate crystals grown from aqueous solution revealed the presence of elliptical growth hillocks. The hillocks were present on both enantiomorphous forms and originated from dislocations, inclusions, and microcrystals attached to the growing surface. The value of the surface entropy factor equal to 4.55 at 313 K suggests that crystals grow via/or with the participation of dislocation mechanism, and the hillocks are dislocation growth centers. Compound mechanism controlled growth of some crystals because edge nucleation and dislocation centers operated simultaneously on the same surfaces.
Structure of 3β, 20‐diacetoxy‐16α‐methyl‐allopregn‐17(20)‐ene
Authors: Singh Attar , Gupta Vivek K. , Rajnikant  , Goswami K. N.
Published: January 2007

C26H40O4, a steroid (3β, 20‐diacetoxy‐16α‐methyl‐allopregn‐17(20)‐ene) crystallizes in the orthorhombic space group P212121. The unit cell parameters are a = 10.745(2), b = 11.190(3), c = 20.208(1) Å. The structure has been elucidated by direct methods. The final residual index (R) converges to 0.042, weighted residual index (wR) being 0.044. Rings A and B adopt normal chair conformation whereas ring C is found to be very close to chair and ring D exists in 14α‐envelope conformation. The ring junctions A/B, B/C, C/D are trans‐fused about the bonds C5–C10, C8–C9 and C123–C14, respectively.
Positron lifetime study in BaTiO3 ceramics with different Ba/Ti ratios
Authors: Tang C. Q.
Published: January 2007

The positron lifetime spectra in 0.25 at.% La‐doped BaTiO3 with different Ba/Ti ratios have been measured at room temperature. It was found from the experiments that with deviating from exact stoichiometry the positron lifetime τ2 decreases and the intensity I2 increases for Ba/Ti ratio smaller than stoichiometric and they have more significantly similar changes for Ba/Ti ratio larger than stoichiometric. The non‐monotonic dependence of positron lifetime parameters on Ba/Ti ratio is regarded as that the τ2 component is contributed together by positrons annihilating at the grain boundaries and Ba vacancies and/or Ti vacancies, and small deviations from exact stoichiometry would be expected to increase the concentration of defects such as Ba vacancies for Ba/Ti < and Ti vacancies for Ba/Ti > 1.
Liquid phase epitaxial growth and characterization of thin In1−xGaxAsyP1–y layers lattice‐matched to InP
Authors: Becher S. , Gottschalch V. , Wagner G. , Schwabe R. , Staehli J.
Published: January 2007

Growth studies enabled the deposition of In0.71Ga0.29As0.68P0.32 single quantum well structures with InP or In0.88Ga0.12As0.26P0.74 confinement layers lattice‐matched to (001) InP by liquid phase epitaxy (LPE). Well widths in the order of 50–100 Å have been achieved using a conventional step cooling technique. The physical characterization has demonstrated the capability of the employed method to produce multilayered heterostructures which display confined particle states; quantum mechanically induced blue‐shifts of the low temperature PL‐emission up to 125 meV were measured. A remarkable reduction of the FWHM values of the shifted PL peaks was attained by optimization of the growth conditions.
Investigation of the formation and growth processes of silicon carbide monocrystals
Authors: Lilov S. K.
Published: January 2007

The formation and growth processes of SiC monocrystals from vapour phase by sublimation method have been investigated. It is shown that the peaks of the evaporation and growth whiskers are the centres of SiC monocrystals formation. One of the mechanisms of development of the whisker into SiC platelet is established. It is shown that on the naturally mirror like crystal face either the edge of the crystal or the screw dislocation, situated on the crystal edge, is the source of the steps. On the stepped crystal face the root of the crystal is the source of the steps.
Synthesis and X‐ray structure studies of complex [Cu(o‐phenanthroline)2 (saccharin)] · (saccharin) · 2 H2O
Authors: Yugeng Zhang , Jianmin Li , Jing Wei , Xingtao Wu , Shaowu Du
Published: January 2007

The title compound has been synthesized and its crystal structure determined at room temperature, Mr = 824.34, triclinic, space group P–1(2), a = 13.622(4), b = 13.770(4), c = 11.167(3) Å; α = 104.83(2), β = 110.01(2), γ = 62.04(2) degree; U = 1727.0(9) Å3, Z = 2, Dcalc = 1.59 g/cm3. The final R is 0.066 for 3299 independent observed reflections with I ≧ 3σ(I). The crystal structure consists of repeated [Cu(o‐phen)2(sac)]+ cations, non‐coordinated saccharin anion and two lattice water. And the central ion Cu2+ forms a trigonal‐bipyramidal stereochemistry.
Thermoelectric power of indium sesquisulphide single crystals
Authors: Nassary M. M.
Published: January 2007

The investigation covers a temperature range from 200 to 450 K. Thermoelectric power measurements of In2S3 crystals showed that all samples under investigation have a positive TEP in all temperature ranges, indicating n‐type conductivity for In2S3 crystals. The ratio of the electron and hole mobilities is μn/μp = 4.71. The effective mass of electrons m is found to be 0.00008 × 10−31 kg. The obtained effective masses of holes m = 1.893 × 10−31 kg. The diffusion coefficient for both carriers (electrons and holes) is evaluated to be 84.71 cm2/s and 17.985 cm2/s respectively. The mean free time between collision is estimated to be τn = 1.7 × 10−20s, and τp = 8.5 × 10−17s. The estimated diffusion length for electrons is found to be Ln = 1.2 × 10−9 cm and Lp = 3.9 × 10−8 cm.
Gas etching of GaAs monocrystalline substrates in the presence of Ga‐ and In sources
Authors: Popov A. S. , Hitova L. , Atanasova R. K. , Nikolova S. L.
Published: January 2007

A special case of gas etching of GaAs substrates in the process of VPE in the presence of (Ga + In) source was investigated. The dependence of the etching rate on the source and the substrate temperature, and the AsCl3 content in the gas flow was studied.
On voids in InxGa1−xSb crystals grown by an ultrasonic‐ vibration‐introduced Czochralski method
Authors: Kumagawa Masashi , Tsuruta Takuya , Nishida Naoki , Ohtsuki Jun , Takahashi Katsumi , Adachi Satoshi , Hayakawa Yasuhiro
Published: January 2007

The shape and size of voids, and the grown region surrounding a large void were investigated in InxGa1–xSb crystals, which were pulled under the introduction of ultrasonic vibrations into the source melt by using a modified Czochralski apparatus. The presence of voids in crystals resulted from (1) atmosphere gas was confined beneath the growth interface of a seed crystal during the seeding procedure, and (2) many bubbles–generated by the cavitation effect due to ultrasonic vibrations–were caught in the growing crystal. Voids were circular, deformed trapezoid, and complex in shape, and were in a range of 20 μm to 3 mm in size. Even in case of a void with the diameter as large as 2 mm, the grown region surrounding it was in the single crystalline state. In this interesting region, the microscopic variation of In concentration and the abrupt change of growth rate were observed.
Growth kinetics of RF‐sputtered nickel films in the beginning stages
Authors: Mikhailov I. F. , Fomina L. P. , Borisova S. S. , Babenko I. N. , Melnik N. N. , Pudonin F. A.
Published: January 2007

By the analysis of X‐ray reflectivity angle dependence the existence of a characteristic nucleus height h in the island stage of nickel growth have been found. As the condensation time τ rises, the value of h increases according to a linear law, and the portion of substrate surface occupied by nuclei is described by a curve with saturation. The formation latent period of the fraction with preferential size h is extremely small, that, in principle, allows to produce smooth surfaces, even if the effective thickness is only about several atomic layers. The kinetic characteristics are identical both at growing on monocrystalline silicon and amorphous SiOx substrates.
A possibility for improvement of the quality of quartz crystals
Authors: Nanev Chr. N. , Zahariev P. G.
Published: January 2007

Experiments intended to improve the quality of seed plates for hydrothermal synthesis of quartz crystals have been performed. The plates were subjected to electro‐sweeping of alkali cations. More perfect crystals were grown on such seeds.
Growth rate dispersion in batch and continuous configurations
Authors: Tulke A. , Offermann H.
Published: January 2007

The existing models describing growth rate dispersion don't consider a healing process of crystal damages or surface defects. In this paper a model is presented which takes into account such a healing process. With regard to the new model formulas, characterizing the crystal size distribution, are derived from the population balance and discussed. The considerations are extended to continuous crystallizers.
Crystal structure of a daturalactone – A withanolide
Authors: Padha Naresh , Kalyandas  , Dhar K. L. , Goswami K. N.
Published: January 2007

The crystal structure of a daturalactone derivative has been determined by X‐ray structural analysis. The compound crystallizes in orthorhomic space group P212121 with cell parameters a ‐ 15.141(1) Å, b ‐ 18.425(1) Å, c ‐ 19.251(2) Å. The structure was solved by direct methods and refined to R ‐ 0.082. The asymmetric unit contains two non‐equivalent molecules. Extensive hydrogen bonding is present. The conformations of the rings are A: a distorted half‐chair, B: a perfect half‐chair, C: a chair, D: an envelope‐half chair and E: a twist boat. Ring junctions A/B, B/C, C/D are all trans fused. Methyl carbons C(18), C(19), C(27) and the lactone moiety is β‐oriented whereas the methyl carbons C(21) and C(28) are α‐oriented.
The crystal structure of SrCl2 and BaCl2 hemihydrates by powder diffraction
Authors: Łasocha W. , Michalec M.
Published: January 2007

The crystal structures of isomorphous SrCl2 and BaCl2 hemihydrates were solved by powder diffraction method. Strontium and barium atoms are coordinated either by nine chloride atoms or by seven chloride and two oxygen atoms. Space group: Pmmn(59), lattice parameters: a ‐ 15.976(1), b ‐ 4.260(5), c ‐ 8.090(1) and a ‐ 16.477(5), b ‐ 4.555(1), c ‐ 8.330(3) Å, for strontium and barium compound, respectively. Rietveld refinement results in the discrepancy factors RB ‐ 10.85, Rwp ‐ 12.71% and RB ‐ 4.50% for SrCl2 and BaCl2 hemihydrate, respectively.
Infrared vibrational Modes in Tl3SbS3, Tl3AsS3, and Tl3AsSe3 crystals
Authors: Syrbu N. N. , Krasovsky V. T. , Grincheshen I. N.
Published: January 2007

Reflectivity spectra of Tl3SbS3, Tl3AsS3, and Tl3AsSe3 crystals have been investigated in the wave number range 50–600 cm−1 for the polarizations E∥c and E⟂c. The fundamental phonon parameters, the limiting dielectric constants ϵ∞ and ϵS and the reflectivity spectra contours have been calculated by using classical dispersion relations for both E∥c and E⟂c configurations. The Szigeti effective charges and the relative ion charges of As, Tl, Sb, Se, S anions and cations have been calculated in dependence on the incident light polarization.
Experimental confirmation of the peculiar behaviour of the coherent‐type twin boundaries in sphalerite crystals
Authors: Minchev G. M. , Pramatarova L. D. , Podor B. , Szabo J.
Published: January 2007

This paper presents an experimental confirmation of the peculiar behaviour of coherent twin boundaries in sphalerite crystals through a “two step” experimental procedure involving free abrasive polishing for the “developing” of the stress pattern and infrared whole‐sample optical reflection (“magic mirror”) for the registration. The results are in accordance with the novel static atomistic simulations of the grain boundaries.
Structural investigation on the influence of clathration of metal amine complexes and its effective parameters
Authors: El‐Shabiny A. M. , El‐Zein S. M.
Published: January 2007

The clathrates of Ni‐ and Co‐Werner complexes with o‐, m‐, and p‐xylenes were studied in order to explain the controlling factors affecting clathration. The complexes and their clathrates have been investigated using an analytical X‐ray powder diffraction procedure for the structure determination. It was found that clathration degrades the lattice symmetry, deforms the crystal and decreases the cell volum when accompanied by a change in the crystallographic system. The possibility of clathration increases as the cell volume of the complex (host) increases. Lower polarity and better fitting into the complex lattice increase selectively. Thus, clathration is strictly governed by the shape and polarity of the guest molecule rather than its volume.
On the (MgxNi1–x)SeO4 · 6 H2O and (MgxCu1–x)SeO4 · 5 H2O mixed crystal formation
Authors: Stoilova D. , Ojkova T. , Staneva D.
Published: January 2007

Mixed crystals (MgxNi1–x)SeO4 · 6 H2O and (MgxCu1–x)SeO4 · 5 H2O have been prepared studying the solubility in the MgSeO4–NiSeO4–H2O and MgSeO4–CuSeO4–H2O systems at 25 °C. It has been shown that the monoclinic structure of MgSeO4 · 6 H2O is unstable and undergoes a change into tetragonal structure due to the included nickel ions (about 4 at %). The lattice parameters of (MgxNi 1–x)SeO4 6 H2O have been calculated. It has been established that the magnesium ions incorporate isodimorphously in the crystal structure of CuSeO4 · 5 H2O which could be an indication of the existence of MgSeO4 · 5 H2O isostructural with the triclinic CuSeO4 5 H2O. The distribution coefficients of the salt components between the liquid and solid phases have been calculated.
Growth of CdGeAs2 single crystals by a microprocessor‐controlled bridgman system
Authors: Manimaran M. , Ramasamy P.
Published: January 2007

A microprocessor‐controlled Bridgman system was designed and fabricated for the growth of II‐IV‐V2 compounds and one of this group of compounds CdGeAs2 has been grown using a two‐zone vertical Bridgman systein. The grown crystals have been characterized by X‐ray and Hall effect.
Temperature‐gradient‐double‐crucible method for high‐temperature solution growth
Authors: Jung P. A. , Schwabe D. , Scharmann A.
Published: January 2007

We report on a special technique for high‐temperature solution growth (flux‐), which can be used to grow compounds which have only a small solubility in the flux or only exist in a small existence range (concerning temperature and concentration). By two crucibles placed into one another, an inner growth region will be separated from an outer solution region. The regions are connected by holes in the inner crucible. By this method BaSO4 crystals of high quality are grown from NaNO3 flux and LiCl–KCl flux. Growth experiments using this method were done with the incongruently melting high‐temperature superconductor YBa2Cu3O7‐δ.
X‐ray investigations on the defect structure of KCl with Cd++ impurities
Authors: Saravanan R. , Mohanlal S. K.
Published: January 2007

A systematic defect characterization by X‐ray diffraction was carried out on crystalline KCl system with Cd++ impurities at various levels, viz. 2, 4, 6, 8, and 10 mole%. Quantitative estimation of the amount and nature of defects was done from the integrated X‐ray intensity measurements of the samples. Further analyses of the experimental data indicate enhancement of the Debye‐Waller factor with concentration of Cd++ impurities. The measured density and the cell constant values at room temperature yield vacancy estimations for the system. The observed change of Bravais lattice of the system for Cd++ concentrations from 4 mole% with appreciable enhancement of intensity of Bragg reflections of mixed indices are reported and discussed.
The Ln–Ba–Cu–O (Ln = Lanthanoid) systems: Compounds and compatibilities in air at 900–980°C
Authors: Chodorowicz‐ba̧k A. , Hodorowicz E. , Hodorowicz S. A.
Published: January 2007

Comparison of phases observed in air at 900–980°C in the Ln–Ba–Cu–O (Ln = Lanthanoid) systems is reported. On the basis of the occurrence of compounds found in these Ln2O3–BaCO3–CuO systems they must be divided into at least three subgroups: the first is characteristic of La, Pr and Nd, the second specific for Sm and Eu, and the third common to the smaller lanthanoids, the Y‐type elements, with some variation within the groups.
Enantiomorphism in sodium chlorate crystals
Authors: Szurgot Jadwiga , Szurgot Marian
Published: January 2007

Creation of enantiomorphous forms in sodium chlorate and enantiomorphous nature of surface micromorphology were studied by optical microscopy. It was shown that when the small number of crystals nucleates spontaneously in unstirred, unseeded solutions then exclusively left‐ (L) or right‐handed (D) crystals can be formed. At the large number of nucleated crystals the probability of the creation of L and D form is nearly the same. L and D crystals can be distinguished by the shape of growth or dissolution centers.
The structure of mixed crystals KNO3. x NH4NO3
Authors: Galdecki Z. , Czurak W. , Fruziński A. , Dejewska B.
Published: January 2007

Five salts of KNO3. x NH4NO3 with different x values have been synthesized and their structures have been solved and refined. X values obtained from refined fractional occupation number of K atom are in accord with x obtained from chemical analysis. The linear dependence of volume cell on obtained x has been given.
On the anharmonic vibrations in crystalline silicon
Authors: Saravanan R. , Mohanlal S. K. , Netaji M.
Published: January 2007

Using a total of 1052 Bragg reflections of silicon, an X‐ray investigation has been carried out to deduce the anharmonic thermal parameter β, apart from the estimation of the harmonic contribution of the thermal vibration at room temperature. Reflections of type h + k + l = 4n, and 4n ± 1 were used to estimate these parameters using MoK α radiation and a Nonius CAD‐4 X‐ray diffractometer. We obtain Bsi, = 0.451(0.008) Å2 and βsi = 0.279(2.630) eV Å−3 with R = 3.12%. The present B and β values are in very good agreement with the earlier studies.
Influence of non‐stoichiometry on the recombination activity of dislocations in undoped semi‐insulating GaAs crystals
Authors: Glinchuk K. D. , Prokhorovich A. V.
Published: January 2007

The effect of non‐stoichiometry of gallium arsenide melt composition on the recombination activity of dislocations in undoped semi‐insulating GaAs crystals is studied and analyzed. It is shown that the deviation from the stoichiometric melt composition is one of the major factors affecting the recombination activity of dislocations in undoped semi‐insulating GaAs crystals. namely: the recombination activity of dislocations is increased when the arsenic‐rich melt is used, and, on the contrary, is decreased when the gallium‐rich melt is used. The regularities observed are explained by the complex processes of interaction of dislocations with the non‐stoichiometry‐induced intrinsic point defects.
Crystal structure of a furo‐[3,2‐g]‐[1]‐benzopyran‐7‐one derivative
Authors: Padha Naresh , Subramanian E. , Dass A. K. , Mazumdar S. K. , Goswami K. N.
Published: January 2007

The crystal structure of 9–(1,1‐dimethyl–2‐propenyl)‐4‐hydroxy‐7H‐Furo‐[3,2‐g]‐benzopyran‐7‐one has been determined from X‐ray diffraction data. The compound crystallizes in the monoclinic space group C2/c with unit cell parameters a = 8.976(3) Å, b = 16.621(2) Å, c = 17.818(2) Å, β = 95.79(2) Å. The gross structure was determined by direct methods and refined to a final value of R = 0.053. The three ring framework of the molecule is nearly planar. The side chain attached at the atomic position C(9) possesses significant foldings and has been found inclined to the ring system of the molecule.
X‐ray diffraction investigation of structure perfection state of silicon crystals after irradiation by fast uranium ions
Authors: Auleytner Prof.J. , Khrupa V. , Briginets A. , Skorokhold M. , Datsenko Prof.L.
Published: January 2007

The results, obtained from U‐implanted silicon crystals, are presented. Disclocation‐free Si‐wafers (200 μm thick) were implanted with 16 MeV/n U‐ions using Darmstadt accelerator. The applied dose was of 4.4 · 1012 i/cm2. During implantation the crystal was covered by 2 mm thick copper mask with a circular hole of 8 mm diameter. We present the results which were obtained 4 years after performing the implantation. During this time the crystal was kept at the room temperature. Various X‐ray diffraction methods have been applied to characterize the state of crystal perfection.
X‐ray study and physico‐chemical analyses of magnesium hexaaquabromate
Authors: Lutoslawska‐Rogóż J. , Kapturkiewicz‐Kowal E. , Hodorowicz S. A.
Published: January 2007

Magnesium hexaaquabromate (Mg(H2O)6(BrO3)2) was obtained and analysed by means of X‐ray powder diffraction, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) technique. A thermal analysis of the compound was also carried out. In the temperature range 293–77 K there was no structural phase transition detected. The space group of the compound was found to be Pa3 and the structure of the magnesium hexaaquabromate was refined using the Rietveld method.
Relationship between refractive index, optical electronegativities and electronic polarizability in alkali halides, III–V, II–VI group semiconductors
Authors: Reddy Dr. R. R. , Nazeer Ahammed Y.
Published: January 2007

Refractive indices have been evaluated from DUFFY'S optical electronegativities. The validity of the proposed empirical relation has been tested in the case of II–Vi, III–V compound semiconductors and alkali halides by comparing the calculated values of n with those in the literature. The estimated refractive indices are used in Classius‐Mossotti relation to evaluate electronic polarizabilities in the above compounds. The nature of the bonding in terms of Δχ and n is discussed. Good agreement is observed between the computed and literature values of electronic polarizability.
Growth and Kinetic Measurements of Triglycine Sulphate Crystals
Authors: Alexandru H. V. , Berbecaru C.
Published: January 2007

Synthesis and two‐step recrystallisation have been used to produce TGS basic substance. Kinetic measurements have been performed for (110)‐type face on a large scale of supersaturations up to about 3%. Evidences of impurity influence for small supersaturation and the “coverage” effect has been estimated.
Deposition Efficiency Reducing Reactions in Silicon Deposition from Silane at Low Pressure
Authors: Kühne H.
Published: January 2007

Silane pyrolysis at polysilicon low‐pressure‐deposition conditions is analyzed along the reactor‐tube axis with respect to the existence of competing decomposition reactions leading to the formation of silicon‐containing gaseous byproducts. The presence of such a parallel reaction is indicated by a difference between silane decomposition efficiency ηSiH4 and silicon deposition efficiency ηsi. The rate of such a competing parallel reaction is influenced by the variation of deposition temperature and/or substrate area of silicon deposition. It is drastically accellerated by the presence of phosphine in the gas phase. For the latter case the competing parallel reaction is shown to occur as a homogeneous reaction.
The Infra‐red and Raman Spectra of the Solid Solutions in the KNO3–NH4NO3–H2O System at 298 K
Authors: Dejewska B.
Published: January 2007

The infra‐red and Raman spectra of the solid solutions forming in the KNO3–NH4NO3–H2O system have been made. The spectra have been in agreement with the structure of mixed crystals settled previously.
Effect of Terminal Groups on Formation of Crystal Structure in α,γ‐Disubstituted n‐Alkanes
Authors: Kobayashi H. , Yamamoto T. , Nakamura N.
Published: January 2007

The crystal and molecular structure of 1,16‐dibromohexadecane have been determined by X‐ray diffraction. Crystal data; empirical formula, C16H32Br2, formula weight Mr = 384.24, monoclinic, P21/a, a = 31.00(2), b = 5.38(1), c = 5.48(1) Å, β = 90.8(2)°, V = 914(3) Å3, Z = 2, Dx = 1.396 g/cm3, δ(CuKα) = 1.5418 Å, μ(CuKα) = 55.41 cm−1, F(000) = 396.00, T = 293 ± 1 K, wR = 0.082, R = 0.054 for 940 unique reflections [I > 3.00σ(I)]. The molecular skeleton has an all trans zigzag hydrocarbon chain. The crystal has a layer structure, but the directions of molecular axes in neighbouring layers alternate. This molecular packing resembles to that of 1,16‐hexadecanediol, whereas n‐alkanes or α‐monosubstituted n‐alkanes do not appreciably have these molecular arrangement. The effect of terminal groups at both ends of α,ω‐disubstituted n‐alkanes on the crystal structure is discussed.
Analysis of the Diametral Response of a Czochralski Crystal (III) Solution of the Equation Set. Transfer Functions
Authors: Sveshtarov P. , Gospodinov M.
Published: January 2007

The paper is the third in a series which presents 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. For typical growth conditions and a wide range of materials it has been shown that this response is obtained by solving a set of linear differential equations. Conditions for normal response, i.e. the diameter increasing on heater temperature and/or pull rate decrease, have been established and shown to hold for most practical cases. The transfer function obtained is consistent with previous results for an inductively heated growth apparatus.
Microhardness Studies of Pure and Doped Crystals of Lead(II)Chloride and Lead(II)Bromide
Authors: Sagayaraj P. , Sivanesan S. , Gobinathan R.
Published: January 2007

Single crystals of pure and monovalent metallic ion doped (K+, Na+, Cu+, Ag+, and Hg+) lead(II)chloride and lead(II)bromide were grown using silica gel. The growth experiments have been carried out by employing a modified two‐stage chemical reaction. The grown crystals of pure and doped lead(II)chloride and lead(II)bromide are subjected to microhardness studies. The validity of Kick's relation is checked. The value of standard hardness number Hv and the work hardening coefficient n are found out. The influence of the presence of the added dopant on the microhardness behaviour of the crystal is studied. A possible relation between the hardness value Hv and the ionic radii of the added dopants is established and the results are discussed.
Electrical Properties of Praseodymium‐doped GaAs and Al0.3Ga0.7As Epilayers
Authors: Lai M. Z. , Chang L. B. , Chen C. C. , Wang H. T. , Jiang G. C.
Published: January 2007

Praseodymium‐doped GaAs and Al0.3Ga0.7As epilayers grown on Semi‐Insulating (SI) GaAs substrates by Liquid Phase Epitaxy (LPE) were first studied in this present work. Measurement techniques, such as microscopic observation, X‐ray diffraction, Secondary Ion Mass Spectroscopy (SIMS), and Hall measurement were employed. Layers doped with Pr resulted in a mirror‐like surface, except several high Pr‐doped layers having droplet surfaces. Hall measurements reveal that the grown layers contained p‐type layers, carrier concentrations from 6.3 × 1015 to 1.2 × 1016 cm−3, and from 6.3 × 1015 to 3.5 × 1016 cm−3 for Pr‐doped GaAs and Al0.3Ga0.7As epilayers, respectively. Although p‐type conduction exists, in the light of electrical features, doping of Pr into the GaAs and Al0.3Ga0.7As growth melts, is still considered to exhibit gettering properties rather than to become a new acceptor itself. Additional photoluminescence examinations were taken. Their results also indicate that Pr‐doped layers produce no new emission lines and support the electrical observations.
The Ostwald Rule of Stages
Authors: Nývlt Jaroslav
Published: January 2007

Crystallization from solutions often starts in such a way that thermodynamically unstable phases appear first followed by recrystallization to thermodynamically stable phases. This empirical observation, called as Ostwald's rule of stages, is explamed here on the basis of structure changes of solutions. Experiments supporting this explanation have been carried out with aqueous solutions of citric acid, sodium hydrogen phosphate and ferrous sulphate, respectively.
Growth Processes and Properties of Fe‐ and Co Electrodeposited Alumite Films
Authors: Shadrow V. G. , Boltushkin A. V. , Tkachenko T. M. , Semeshko A. V. , Komarovskaya Y. D.
Published: January 2007

Growth processes, structure and properties of Fe, Co, FeCo deposited alumite films have been investigated. It is shown that the magnetic characteristics depends both on alumite film parameters and properties of deposited metal (alloy) particles.
Twin structure of Sodium Hydrogen Oxalate Monohydrate
Authors: Komunjer L. J. , Lefaucheux F.
Published: January 2007

Twin structure of triclinic sodium oxalate monohydrate was determined by means of X‐ray techniques. The twin is formed by reticular pseudomerohedry, with [101] as twin axis and (101) as contact plane.
Working Model for Explanation of Polytype formation Based on Superlattice Ordering of Point Defects in Close Packing Structures
Authors: Kozielski M. J. , Tomaszewicz A.
Published: January 2007

The model is an attempt to give an explanation of polytype orderings in the crystals. Basic assumptions of the model are: the point defects play the important part in the polytype formation; these defects influence the configuration (hexagonal or cubic) of individual layers. The defects have a tendency to ordering themselves into superlattices. It acts selectively on particular stacking of the layer sequences. The results of model operation are shown in examples of experimental data of polytypic materials; they are SiC and AIIBVI compounds.
The Microcamera Used for Photoelectron Excited by the X‐ray Standing Wave (XSW) Recording and Submicron Layer Structure Studies
Authors: Auleytner J. , Godwod K. , Pelka J.
Published: January 2007

Information obtained owing to aquaintance with the course of the angular dependence of photoelectron intensity excited by the X‐ray standing waves allows to determine, more explicitly, the state of crystal surface layer deformation. The aim of this work is to present a new measuring device constructed at the Institute of Physics of the Polish Academy of Sciences, especially the X‐ray microcamera being simultaneously the proportional flowing counter used for measuring of photoelectron current emitted from the examined crystal. The angular dependence of the photoelectron current can be measured in coincidence with the angular running of rocking‐curves. It is possible due to a computer program controlling the X‐ray doble‐crystal spectrometer, the microcamera and the electronic system for registration of the intensity of the diffracted beam as well the flowing counter.

The scheme of the X‐ray double‐crystal spectrometer, the microcamera, and the electronic measuring system operation is given. There are also given the results of the introductory measurements carried out for the Si(111) implanted with the Au ions. The calculation of rocking‐curve for non‐disturbed crystal in the case of asymmetrically cut monochromator crystal was made. There was also estimated the range of depth from that the photoelectrons were emitted.
Influence of F‐Anions on the Habit and Growth Mechanism of Potassium‐rich Feldspars
Authors: Franke Walter A. , Słaby Ewa
Published: January 2007

Orthoclase‐rich alkalic feldspar crystals were grown from melts next to Orthoclase‐Albite‐Quartz eutectic composition at 2 kb in the presence of a surplus of a supercritical aqueous phase by isobaric cooling at a rate of approximately 10 °C/day. Some runs were made with KF‐bearing fluid phase, in two runs the melt was formed during intensive thermoconvection of the fluid phase. Tabular crystals were only formed from F‐bearing melts, crystals grown from F‐free melt were always fan‐shaped. We assume this fact is due to a more easy supply of Al to the growing crystal in melts with F content.
Phase Transition of 1,16‐Hexadecanediol
Authors: Kobayashi H. , Nakamura N.
Published: January 2007

It was found that 1,16‐hexadecanediol exhibited a solid‐solid phase transition. X‐ray diffraction experiments and dielectric constant measurements were carried out in order to investigate the structure of the high‐temperature phase. A model of molecular arrangement in the high‐temperature phase was presented. The high‐dielectric constant values were observed in the high‐temperature phase. It is considered that the high‐temperature phase of 1,16‐hexadecanediol is a rotator phase in analogy with n‐higher alcohols.
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

High 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

During 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

Phase 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

Microtopography 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

Alignment 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

Experimental 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

A 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

DC 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

High 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.