bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural imperfections of crystals as a result of ion implantation
Authors: Aboyan A. O. , Bezirganyan P. A. , Bezirganyan S. E. , Grigoryan A. M. , Tumasyan A. S.
Published: January 2007

The diffraction of X‐rays has been studied in two‐crystal interferometers, the crystals of which had equal interplanar distances and between the blocks of which a non‐diffracting zone was formed as a result of ion implantation. Also the X‐ray diffraction was studied in two‐crystal interferometers, the interplanar distances of which were different and the non‐diffracting zone between the crystals had zero width. It was shown in plane wave approximation that the Moiré patterns should not be formed in case of former interferometers and necessarily arose with the latter type interferometers.
Contribution to transition layer determination for oriented eutectic growth
Authors: Wołczyński W.
Published: January 2007

The thermodynamic approach to isothermal interface located within a transition layer has been presented. The proposed definition of interface has been related to Hunt and Jackson's theory of completely coupled growth. Some thermodynamic definitions of layer thickness and interface surface have been derived. The fourfold point temperature has been determined basing upon the equality of chemical potential of the components in both transition layers.
Electric Characterization of Indium Sesquiselenide Single Crystals
Authors: Nagat A. T. , Nassary M. M. , Hussein S. A.
Published: January 2007

Conductivity, Hall‐effect measurements were performed on δ‐phase In2Se3 single crystals, grown by the Bridgman method over the temperature range 150–428 K, in the directions perpendicular and parallel to the c‐axis. The anisotropy of the electrical conductivity and of the Hall coefficient of n‐type In2Se3 had been investigated. The values of the Hall coefficient and electrical conductivity at room temperature spreads from an order of RH11 = 1.36 × 104 cm3/coul, σ11 = 4.138 × 10−3 Ω−1 cm−1 and RH = 66.55 × 104 cm3/coul, σ = 0.799 × 10−3 Ω−1 cm−1 for parallel and perpendicular to c‐axis, respectively. The temperature dependence of Hall mobility and carrier concentration are also studied.
Determination of the Effective Vacancy Concentrations and the Vacancy Losses after the Quench of Al–Zn–Mg Alloys
Authors: Fabian H.‐G. , Wolter R.
Published: January 2007

On the basis of

the experimental observation of dislocation loops by means of TEM,

the conclusion from this that the concentration of vacancies in the dislocation loops exists at the cost of the vacancy concentration primarily present at Tq, and

the inversion of the decomposition kinetics of Al–Zn–Mg alloys found out by means of resistivity and microhardness measurements, the effective vacancy concentration cv.eff being at disposal for the GP‐zone formation was found out by means of the relation tR,max (tR,max being the time required to reach the maximum of resistivity) and the Arrhenius plot In tR,max = f(1/Tq) of the isothermal resistivity measurements. From the comparison of cv.eff with the theoretical V concentration at Tq it is possible to derive statements about the loss of vacancies during and after the quench through loop formation, building‐in of vacancies in GP‐zones and annealing of vacancies at lattice defects.

From this comparison follows:

The ideal ZnV concentration at Tq (calculated by means of the Lomer equation) is sufficiently great to account for the effective vacancy concentration.

The part of cMgV in the loss concentration is rising with increasing cMg.

Both these statements support the hypothesis that the initial process of the decomposition in Al–Zn–Mg alloys is caused by the ZnV diffusion.
Determination of P, B, and Al Concentrations in Si by Photoluminescence (PL)
Authors: Schramm G. , Herzog R. , Kessler H.
Published: January 2007

Calibration curves to determine P, B, and Al concentrations in silicon at 4.2 K from the intensity ratios of bound (BE) and free (FE) exciton related luminescence are presented. The integral relative intensities of the peaks are used besides the peak height ratios. By means of a large number of samples with widely varying concentrations it is shown that the influence of the compensation ratios of the samples on the determination of the dopant concentrations is smaller than the measurement errors. Integral intensity ratios of different BE phonon branches are also derived.
Investigations on the Synthesis of Zeolite ZSM‐5 (III)
Authors: Wilkosz J. , Stobiecka E. , Dudek B.
Published: January 2007

The effect of the chemical composition of the reacting mixture (RM) on the amount of zeolite ZSM‐5 and other crystalline phases and the amorphous phase as well in the obtained preparations was investigated. Ethylenediamine (ED) served as a templating agent. The quantitative estimation of the phase composition was made on the ground of X‐ray diffraction measurements. Zeolite ZSM‐5 of maximum phase purity of 96%, contaminated mainly with quartz and mordenite, was obtained.
Estimation of the Chemical Transport Behaviour of Transition Metal Silicides MeSix (Me = Cr, Ti, V, Mo, Fe, Mn) with X2 (X = Cl, Br, I)
Authors: Krausze R. , Krabbes G. , Khristov M.
Published: January 2007

Chemical vapour transport of transition metal silicides of Cr, Ti, V, Mo, Fe and Mn with halogen was estimated by a simple thermodynamic approach. The content of Si and Me in the gas phase is essential to the prediction of the transport. The dependence of the composition of the gas phase on the solid and the transport agent used is discussed and the results of the estimation are compared with experimental details.
RHEED Studies during Surface Cleaning of Silicon for MBE Substrates
Authors: Dominguez F. , Tempel A. , Zehe A.
Published: January 2007

Silicon wafers were prepared for MBE growth by chemical treatment and temperature annealing under UHV conditions. The (7 × 7) and (2 × 1) reconstruction of {111} and {100}‐oriented Si surfaces were obtained only after high temperature annealing for few minutes at 1200 °C. The reconstruction effects were found to be stable for a long time even if the pressure in the UHV chamber increased to 10−5 Pa.
Growing of Optical Crystals Using a Propagating Temperature Field Technique
Authors: Lingart Yu. K. , Khazanov E. E.
Published: January 2007

Given hereby are the results of mathematical modelling of thermal conditions for the method of travelling temperature field (“travelling wave”). All the estimates have been made for the process of leucosapphire crystallization. Demonstrated are the advantages of the above method as against the horizontally directed crystallization on account of shifting the container.
Liquid‐Phase Epitaxy of (Hg, Cd)Te on CdTe Substrates by a Vertical Dipping Technique
Authors: Winkler M. , Teubner T.
Published: January 2007

Hg1−xCdxTe layers on CdTe substrates were grown from Te‐rich melt solutions by a vertical dipping technique using a special quasi‐closed system with ground‐glass sealing. Results are good reproducibilities of the electrical properties after annealing in Hg‐rich atmosphere (p77 ≈ 2 · 1016 cm−3 μ77 ≈ 500 cm2 V−1 s−1) and of the x‐value, respectively. A horizontal position of the substrate downwards to the melt solution yields, in difference to a vertical one, to homogeneous layer thicknesses. Short meltback steps before growth leads to sharper profiles of composition.
KRS‐5 Crystal Growth in Various Ambient Gases and Polycrystalline Fiber Preparation by an Extrusion Method
Authors: Hou Y. , Wang F. , Quan N. , Wang R. , Zhong H.
Published: January 2007

KRS‐5 single crystals have been grown in three kinds of ambient gases: air, Ar, and Ar + I2. The scattering centers in crystals were inspected and the metal impurities and oxygen content of the crystals were analysed. The polycrystalline fibers with 0.5–1 mm in diameter have been prepared by an extrusion method. The stability and attenuation of the fiber are discussed.
The Influence of Mechanical Activation of Quartz and Quartz/γ‐Al2O3 Mixtures on the Sodium A Zeolite Formation
Authors: Wutzler R. , Klevzov D. , Steinike U. , Hennig H.‐P.
Published: January 2007

It could be shown that the preparation of sodium A zeolite is possible by the reaction of quartz and γ‐Al2O3 with NaOH‐solution. The zeolite formation is dependent on the mechanical preliminary treatment of quartz. Only the partially crystalline part of quartz dissolves and reacts with Al2O3 to form zeolite. The grinding of quartz/γ‐Al2O3 mixtures can in certain limits raise the zeolite formation but essentially only influences the kinetics of the zeolite formation.
Correlation between the Short‐range Parameters and Some Thermodynamic Quantities
Authors: Vassilev G. P.
Published: January 2007

The correlation between the short range parameters and some thermodynamic properties has been examined for 44 binary alloys. Qualitative agreements have been obtained in the majority of the systems. Some previsions have been made for the controversially cases.
Crystal and Molecular Structure of Bis(pyridine)N,N′‐o‐phenylen‐bis[2‐cyan‐2‐ethoxycarbonyl‐vinyl‐amido(–)]‐iron(II)‐Pyridine
Authors: Görls H. , Jäger E.‐G.
Published: January 2007

The crystal and molecular structure of bis(pyridine)N,N′‐o‐phenylen‐bis[2‐cyan‐2‐ethoxycarbonyl‐vinyl‐amido(–)]iron(II)‐pyridine were determined by X‐ray structure analysis. It crystallizes in the monoclinic space group P 21/c with cell parameters a = 9.866(23), b = 19.491(46), c = 16.992(22) Å, and β = 95.19(1)°. The structure was solved by the heavy atom method and refined to R = 0.125. The coordination geometry around the iron atom is octahedrally distorted with the two pyridine molecules in the axial positions.
Thermally Stimulated Luminescence of Montmorillonite Clay
Authors: Somaiah K. , Venkatanarayana M. , Sathyanarayana B.
Published: January 2007

X‐ray excited luminescence (XL) spectra of montmorillonite clay at RT showed a broad emission band around 380 nm with two shoulders at 340, 450 nm eitherside two sharp peaks and two shoulders are seen at 465, 487, and 548, 576 nm, respectively. The 548 and 576 nm peaks enhanced their intensity at LNT. Whereas thermally stimulated luminescence (TSL) revealed an intense glow peak at 355 K and a weak shoulder around 400 K. Room temperature annealing studies indicated that the 355 K glow peak is not as stable as 400 K shoulder which turns out to be a peak on RT annealing. The X‐ray excited luminescence has been attributed to radiative recombination of electrons with holes which are associated with SiO3‐4, AlO4‐4 radicals and divalent impurities available in the naturally available clay. TSL is also understood on similar lines. Glow peak reactions are proposed tentatively and their trap parameters have been calculated.
Elastic Behaviour of Mn–Zn and Mg–Zn Ferrites
Authors: Showry K. , Murthy S. Ramana
Published: January 2007

The elastic moduli of four different composition of mixed Mn–Zn and Mg–Zn ferrites in the polycrystalline form have been measured at the room temperature using the ultrasonic pulse transmission method. The values of Young's modulus and the rigidity modulus are corrected to theoretical density using the method of Mackenzie. From the values of longitudinal and shear velocities, the Debye temperature has been calculated.
Temperature Dependence of Critical Sample Thickness for Spontaneous Cholesteric‐Nematic Phase Transition Between Surfaces with Homeotropic Anchoring
Authors: Pirkl S.
Published: January 2007

Temperature dependence of the critical sample thickness at which a cholesteric structure unwinds spontaneously between surfaces with homeotropic anchoring are presented for some dielectrically negative chiral nematic mixtures. The results obtained are pertinent to the application of the nematic‐cholesteric phase change‐effect in liquid crystal devices.
Phase Transitions in n‐Pentadecanoic Acid: A Polarization Microscopy Study
Authors: Prasad P. B. V.
Published: January 2007

A detailed polarization microscopy study is carried out to explore the nature of the heat induced phase transitions in n‐pentadecanoic acid. A′ (triclinic) → B′ (triclinic) and B′ (triclinic) and C′ (monoclinic) transitions are noticed to be fast and slow, respectively. It is understood that when the other influencing parameters (such as rate of heating) remain identical, in case of several transitions taking place in the same material, then the extent of stuctural difference between the mother and daughter phase is the transition rate determining factor.
Application of Modified Kick's Law to Rhombohedral Crystals: Calcite
Authors: Joshi D. R. , Pandya J. R.
Published: January 2007

Optical study of mechanical response indicated by Knoop indentation of cleavage faces of natural rhombohedral clacite crystals based on MEYER'S law/KICK'S law (P adn) and also on modified KICK'S law (P–W) = bd2 is made. The response of cleavage faces for low load region (LLR) and high load region (HLR) of applied loads P to produce indentation mark of longer diagonal length is different. In LLR the Newtonian resistance pressure W is negative and varies with orientation and quenching temperature whereas in HLR it is positive and almost constant at room temperature and quenching temperatures. In LLR, W indicates crystal anisotropy. The values of resistance pressure W2 and standard hardness b2 in HLR are independent on thermal treatment and are constant within experimental limits. Since they are independent on indenter orientations, they are not associated with crystal anisotropy.
Infrared FTS‐Ellipsometry in the Investigation of Smectites
Authors: Hoeding T.
Published: January 2007

The paper presents IR spectra of montmorillonites and nontronites obtained with absorption measurements and FTS‐Ellipsometry. FTS‐Ellipsometry is a new method in the investigation of the vibration behaviour of clay minerals. The combination of these two IR methods enables the presentation of certain differences in the IR spectra of montmorillonites, also in the spectral region 1200 to 400 cm–1. Differentiations between special varieties and semiquantitative estimations (especially for iron) are possible.
Synthesis, Characterisation and Phase Transition Studies of 50.9 and 90.5
Authors: Pisipati V. G. K. M. , Rao N. V. S. , Reddy M. V. V. N. , Rao C. G. Rama , Padmavathi G.
Published: January 2007

The synthesis, characterisation of phases of the compounds N(p‐n‐pentyloxy benzylidene) p‐n‐nonylaniline, 50.9 and N(p‐n‐nonyloxy benzylidene) p‐n‐pentylaniline, 90.5 and phase transition studies using different experimental techniques are presented. The compound 50.9 exhibits a phase sequence NAB whereas 90.5 shows a phase variant ABG. A large density jump across IN transition is observed in 50.9 similar to that observed in 50.10 compound.
Characterization of a Trench Etching Process Using CBrF3 and Optimal Emission Spectroscopy of the Plasma
Authors: Wöhl G. , Haščik S.
Published: January 2007

Dry processes for deep silicon trench etching using CBrF3 were studied. The experiments were done in a single‐wafer reactive ion etcher in a low frequency and a high frequency mode. By optical emission spectroscopy of the CBrF3 plasma relative Br‐, F‐, CF3‐, and Br+ concentrations were measured as a function of applied frequency, pressure and power. Finally, in connection with d.c. bias voltage measurements some aspects of the etching mechanism are discussed.
Determination of Concentration of Rare Earth Ions Yb3+, Er3+, Tb3+, Ho3+, Tm3+ in Monocrystals of Yttriumaluminum Garnets on Basis of Magnetic Susceptibility
Authors: Dodokin A. P. , Kevorkov A. M. , Perlov D. D. , Sorokin A. A.
Published: January 2007

Crystals of solid solutions (RxY1‐x)3Al5O12 (where R is rare earth ion Er3+, Yb3+, Tb3+, Ho3+, Tm3+) with garnet structure were grown. The temperature dependencies of magnetic susceptibility for these crystals were obtained. On the basis of measurement of magnetic susceptibility a non‐destructive technique for determining the concentration of rare earth ions in yttrium‐aluminum garnets was developed.
Some Possibilities for Investigation of the Energetics of Thin Ag Films on W
Authors: Michailov E.
Published: January 2007

On the grounds of adsorption‐desorption equilibrium measurements (ADE), by means of massspectrometer techniques (MS), a family Ag/W adsorption isotherms was obtained. The isotherms were analysed on the basis of a simple model, which allowed to reduce the well known equations of two‐dimensional (2D) state to an Arrhenius form, which was finally used to investigate the energetics of Ag–W and Ag–Ag interactions. The presence of real attractive Ag–Ag lateral interactions was established. The lateral binding energy per bond was estimated to be ∼ 0.065–0.088 eV/atom and ∼ 0.152 eV/atom for the first and second monolayers (ML), respectively.
Melt Growth of CdTe Crystals and Transmission Electron Microscopic Investigations of their Grain Boundaries
Authors: Sabinina I. V. , Gutakovski A. K. , Milenov T. I. , Lyakh N. N. , Sidorov Y. O. , Gospodinov M. M.
Published: January 2007

Transmission electron microscopy investigations are carried out on CdTe crystals grown in quartz ampoules in a temperature region (1020–1091 °C) near to the melting point of 1092 °C, by travelling heater method in quasi‐closed and in sealed (at 0.135 Pa) volume, and by the Bridgman method from nearly stoichiometric melts. An original method for preparation of CdTe thin foil is reported. Two types of grain boundaries are observed: high‐angle misoriented grain boundaries (more than ten degrees misorientation between adjacent grains) and low‐angle misoriented grain boundaries (less than one degree misorientation between adjacent sub‐grain). Both dislocations with Burgers vector b = a/6 〈112〉 and b = a/2 〈110〉 are present.
Microinhomogeneities of Charge Carrier Concentration in GaAs
Authors: Kallenowsky T. , Koi H. , Boudriot H. , Oettel O. , Schneider H. A.
Published: January 2007

The tendency towards higher and higher integration of electronic components leads to increased requirements to the quality of the base material. The main requirement is homoneity of sturctural and related electronic and optoelectronic crystal properties of the base material within microscopic (and still decreasing) areas, in correspondence with the specific application.

This paper is to present investigations of the correlation between local fluctuations of the charge carrier concentration and the occurrence of growth‐related striations in terms of IR absorption.
Growth Mechanism and Twinning of Sucrose Effected by Surface Adsorption Processes
Authors: Döhl B. , Follner H.
Published: January 2007

Growth experiments with sucrose dependent on temperature and supersaturation of solutions were carried out to find the conditions for appearance of the three different growth types. Measurements of growth rates of {110} and {110} faces at 50°C and supersaturation cs = 10% resulted in the known feature that in pure solutions a crystal grows faster in positive b‐direction than in the negative one. Addition of raffinose stopped growth of {110}. In an electric field generated by 20 kV direct voltage (crystal orientation: negative pole of b‐axis pointed towards the negative electric pole) the crystal grew in negative b‐direction three times faster than in the positive one. In the presence of raffinose the growth rates in both directions become equal. If the crystal is turned by 180° in the solution (pure solution and in the presence of raffinose) the growth behaviour is the same as without an electric field. These results can be interpreted in such way that in pure solutions sucrose molecules adsorb to {110} (bonds exist between the fructose rings of molecules in liquid and solid phases) and that in presence of raffinose these molecules adsorb to {110} (bonds exist between glucose (solid) and galactose rings (liquid phases)). By the electric field the adsorption is hindered. The theory is in accordance with the fact that crystals situated in a suspension of the solution can intergrow with a host crystal in twin positions (in pure solutions on {110} and in the presence of raffinose on {110}).
Semi‐Batch Precipitation of Calcium Oxalate Monohydrate
Authors: Millan A. , Grases F. , Söhnel O. , Křivánková I.
Published: January 2007

Calcium oxalate monohydrate (COM) formation on the semi‐batch precipitation of CaCl2 and Na2C2O4 solutions in the stoichiometric ratio carried out at pH = 6 and 37 or 70°C, respectively, was studied. When a certain level of supersaturation in the system is reached, individual COM crystals of a rather uniform size are formed. These crystals then grown and form ‘loose’ agglomerates that later develop into compact and spherical particles. The particle size distribution (PSD) rapidly shifts during early stages of precipitation towards larger sizes as a result of crystal growth and agglomeration. Later the PSD reaches a shape and position on the size axis that remain virtually constant with progressing precipitation. COM agglomerates consisting of mainly intergrown crystals are formed by mechanism of primary and secondary agglomeration. The primary agglomeration can constitute an important factor in urolithiasis.
Structure of Polycrystalline Cu Films as Solar Selective Coatings
Authors: Ramadan A. A. , Abdel‐Raheem S. K. , El‐Shabiny A. M. , Kaid M. F.
Published: January 2007

Copper thin films (5–150 nm) were prepared by vacuum deposition with different rates (0.7, 1.5 and 3 nm/s). The position, intensity and profile of X‐ray diffraction lines were analysed to study the phases, the crystallographic preferred orientation as well as the residual strain and crystallite size. The fcc polycrystalline Cu phase was revealed and no oxide phases were identified. The films were highly oriented with 〈111〉 fiber texture. The ratio of P111/P200 increased with the film thickness. Thus, in case of amorphous substrate, the type of the crystallographic texture of a film depends mainly on the structure of the deposited material. The crystallite size increases while the residual strain decreases, as the film thickness or the deposition rate is increased. The crystallite size was very small compared with the film thickness. The effect of deposition rate was pronounced specially from 0.7 to 1.5 nm/s.
Structure‐Property Investigation of TAMP, TAMS, and TAMM Crystals
Authors: Genbo Prof. Su , Jiangxian Wu , Feng Pan , Youping He , Zhengdong Li , Qingzhen Huang , Jingkui Liang
Published: January 2007

The thermal properties, the powder second‐harmonicgeneration (SHG) signal and some electrical properties of the TAM‐tetraoxygen‐acid‐salts, e.g., (HOH2C)3CNH3 · H2PO4 (TAMP), ((HOH2C)3 · CNH3)2SO4 (TAMS) and (HOH2C)3CNH3 · NH4 · MoO4 (TAMM), are reported. TAMP and TAMM are established to be useful nonlinear optical materials.
Crystal Structure Determination of Nickel (2,2‐Dipyridyl) Sulphate Hexahydrate [Ni(C10H8N2) · 4 H2O]SO4 · 2H2O
Authors: Farag I. S. Ahmed , Gad A. A. M. , Awadallah R. M.
Published: January 2007

[Ni(C10H8N2) · 4 H2O]SO4 · 2 H2O, Mr = 418.7, monoclinic, P1, a = 7.781(3), b = 9.421(3), c = 11.457(4) Å, α = 87.54(2)º, β = 96.40(2)º, γ = 102.58(2)º, ν = 814.5 Å, Dx = 1.26 g/cm3, Z = 2, (MoKx) = 0.71073 Å, μ = 7.0 cm−1: T = 23 °C, R = 0.047 for 2139 reflections having intensities greater than 36. The structure was solved using the Patterson heavy‐atom method and the remaining atoms were located in succeeding difference Fourier syntheses. The structure was then refined by full matrix least‐squares using anisotropic temperature factors. Hydrogen atoms were located and their positions and isotropic parameters were refined.
The Crystal and Molecular Structure of 1α,2α‐Methylene Gibberellin A3 Methyl Ester
Authors: Kutschabsky L. , Kretschmer R.‐G. , Voigt B. , Adam G.
Published: January 2007

The three‐dimensional structure of the 1α,2α‐methylene gibberellin A3 methyl ester has been determined by single‐crystal X‐ray diffraction techniques. The crystals are monoclinic, space group P 21 with two molecules in the unit cell of dimensions a = 9.236, b = 7.109, c = 14.155 Å and β = 104.61º. The structure was refined to an R‐value of 0.0983 for 1359 observed reflections.
Evaporation Behaviour of TMIn‐TMN Adduct Determined by flame Ionization Detection
Authors: Hagen S. , Seifert W. , Butter E.
Published: January 2007

As the first time the evaporation behaviour of trimethylindium‐trimethylamine (TMIn‐TMN) was investigated with a flame ionisation method. Individual metalorganic components can be detected in rather low concentrations (10−2 Torr) in a hydrogen carrier gas. A reproducible and constant supply could be realised with the solid TMIn‐TMN‐adduct in accordance with the equation for the vapour pressure: Ig p = −2597 · T−1 + 8.748 (p in Torr) in the temperature range 273 K < T < 294 K. 99% of the steady state value of TMIn‐TMN concentrations in hydrogen was reached within 5–7 min after switching the bubbler into the gasstream.
Effect of the pH Value on the Crystallization of La1−δCuδ · 3C2 O4 · nH2O in Hydro‐Silica Gel
Authors: Varghese George , Ittyachen M. A.
Published: January 2007

The effect of pH on the spacing and the width of Liesegang rings has been investigated.
The Formation of NiZn Ferrite from Mixed Hydroxides
Authors: Fischer S. , Töpelmann W. , Scheler H. , Michalk C. , Knese K.
Published: January 2007

The formation of Ni0.5Zn0.5Fe2O4 from mixed hydroxides was investigated by XRD, Mössbauer spectroscopy and magnetic measurement. For the synthesis of the ferrites mentioned not only the hydroxides Ni(OH)2, Zn(OH)2, FeOOH precipitated under defined conditions were used but also a mixture of ZnFe2O4 (obtained by coprecipitation) with aliquout Ni(OH)2 and FeOOH quantitites, aged in aqueous environment. Subsequently, the powders isolated are tempered. The mixed ferrite Ni0.5Zn0.5Fe2O4 is directly formed from the hydroxide products without other oxidic phases being detectable. But no homogeneous distribution of Ni2+ − or Zn2+ −ions in the spinel is obtainable even after tempering at 500 °C. On the contrary, the mixed ferrites arises only to a small extent from the ZnFe2O4, Ni(OH)2 and FeOOH mixture. Mainly, NiO and α‐Fe2O3 are formed. The dependence of processes is discussed in the mixed ferrite phase formation on synthesis, ageing and tempering conditions.
An X‐ray Study of KBrxI1−x Mixed Crystals
Authors: Hussain K. A. , Subhadra K. G. , Sirdeshmukh D. B.
Published: January 2007

KBrxI1−x mixed crystals have been prepared by melting and their X‐ray patterns have been recorded with a powder diffractometer. From measurements of the Bragg reflections, the lattice constants, grain size, lattice straian and mean Deby‐Waller factor have been determined. In the composition region × < 0.2 and × > 0.7, the lattice constant follows Vegard's law. However, in the region 0.2 < × < 0.7 where a miscibility gap has been reported, single phase mixed crystals are formed but the lattice constants have values larger than those expected from Vegard's law, indicating a strained lattice. The lattice strain directly determined from the half‐widths of the Bragg reflections also shows larger values in the same composition region. The mean Debye‐Waller factor shows a decrease with the degree of mixing, assuming a minimum value in the equimolar region.
Structure Charcterization of EDTA Transition Metal Complexes (I) Study on Sr[Co(HEDTA)H2O]2 · 4 H2O
Authors: Jianmin Li , Yugeng Zhang , Jifa Fan
Published: January 2007

The d‐d transition spectrum of Sr[Co(HEDTA)H2O]2 · 4 H2O crystal was recorded at room temperature and experimental results are discussed quantitatively. Using the ligand field theory and the radial wave function of non‐free Co(II), the d‐d transition energy levels of the title compound were calculated. And the results are seen to be in good agreement with the experimental values.
Electical, Magnetic, and Thermal Properties of Cadmium Hydrogen Phosphate Hydrate Crystals
Authors: Hebbar K. C. , Dharmaprakash S. M. , Mohan Rao P.
Published: January 2007

The d.c. electrical conductivity of pelletized samples of cadmium hydrogen phosphate hydrate (CHP) crystals have been studied in the temperature range 50 °C to 250 °C. It has been observed that CHP crystals exhibit ionic conductivity at 140 °C and possess semiconducting property. At room temperature CHP has stable crystal structure. From thermal analysis it is concluded that CHP crystals possess water of crystallization and the material to be diamagnetic.
Kinetics and Trapping Parameters of Thermoluminecence of Sr1−xEuxF2+x Mixed Crystrals
Authors: Sharma T. A. V. , Somaiah K.
Published: January 2007

The kinetics and trapping parameters of thermoluminescence of Sr1−xEuxF2+x mixed crystals have been calculated by using different methods. The trap depths, frequency factors, and order of kinetics of glow curve pattern in several compositions of the system revealed variations with composition.
Phase Transition Studies in Mixed Polymesomorphic Liquid Crystals with Cholesteric and Smectic A Phase
Authors: George A. K.
Published: January 2007

Cholesteric mesomorphism was induced in a polymesomorphic liquid crystal with nematic and smectic A phases by mixing it with a low pitch cholesteric. A variety of mixtures for a wide range of concentrations were studied. It was observed that the addition of cholesteric liquid crystal disrupts the smectic phase of the parent polymesomorphic liquid crystal. The measured valuses of ultrasound velocity and specific volume and their related parameters were found to exhibit anomalies near each of the phase transitions. The mean interaction parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \alpha $\end{document} was estimated for different mixtures and was found to decrease with increasing concentration of cholesteric liquid crystal in the mixture. It was observed that smectic A‐cholesteric transition becomes second‐order at a particular concentration in agreement with the theoretical predictions.
On the Intensity of Kossel Reflections
Authors: Nolze G. , Geist V.
Published: January 2007

The line intensity of Kossel reflections of various single crystals (A1, A2, B3, B4 and C16 type of structure) has been studied experimentally as well as theoretically. In contrast to earlier results high excess intensity of experimental Kossel lines can be explained solely by dynamical diffraction effects without an additional consideration of real structure effects. It has been shown that the different maxima of intensities of Kossel lines found above all result from the different line width. depending strongly on the X‐ray wavelength used (λ = 0.47−8.34 Å): Sole convolution of the theoretical profiles partly transforms the differences in the line width into variation of height.
Computer Simulation of Electron Diffraction Studies of Various Microcrystalline Bodies
Authors: Rajendran K.
Published: January 2007

Electron diffraction of various microcrystalline bodies has been studied and examined by using computer simulation. Diffracted intensity studies indicated that the peak height increases with the scattering factor. First peak of FCC packed and crystalline observed at S = 6.01 Å and for HCP S = 5.0 Å. The amplitude of waves is most probably the same in the distribution function and providing a spectrum of interatomic distances in the crystalline bodies.
Thin Crystals of Urea Grown by Hot Wall Condensation Technique
Authors: Prasad P. B. V.
Published: January 2007

Crystallization of thin crystals of urea by hot wall condensation technique is described. Powder X‐Ray diffraction (XRD) reveals the some decomposition of ura takes place during evaporation.
Thermal Expansion and Superconductivity in Alkali Metal‐ and Silver‐doped BiSrCaCuO System
Authors: Krishna B. Gopala , Chandra G. Ravi , Suryanarayana S. V.
Published: January 2007

Samples with the nominal composition Bi2Sr2CaCu2Oy with na doped at the Ca site and K doped at the Sr site are prepared by solid state reaction method. From the X‐ray diffraction data it is found that all the the samples have exhibited a single phase 2212. The D.C. electrical resistivity data show that for Na‐doped samples the Tc (zero) varies from 80 K to 85 K and for K‐doped samples it is from 79 K to 82 K. The loss of oxygen from these samples around 400°C was confirmed by high temperature dilatometry. The variation of the thermal expansion coefficient (“α”) with temperature for different alkali dopings are discussed. Also the samples with the nominal composition Bi4Sr3Ca3Cu4−xAgxOy (with x = 0, 0.1, 0.2, 0.3) were studied.
A Study of the Metastable Zone in Nylon 12‐Toluene Solution
Authors: Renjun Feng
Published: January 2007

The metastable zone for a nylon 12‐toluene solution was determined in an established constant cooling rate apparatus. Supersaturation solubility curves and the equilibrium solubility curve are unparallel one to another. The metastable zone width under seeded conditions is dependent on the cooling rate, the retention time and the saturation temperature. And the metastable zone width under unseeded conditions is dependent on the cooling rate, the agitation rate and the saturation temperature. Through constant cooling rate crystallization experiments, two empirical correlations pertaining to the metastable zone of the solution have been found.
Observation of Crystal Growth Hillock Morphology by Using a phase Conjugation Interferometer
Authors: Yue Xuefeng , Yu Xiling , Liu Youchen , Zhang Qincheng
Published: January 2007

Detailed experimental arrangements of phase conjugation interferometer used in the studies of crystal growth hillock morphology are discussed. This method is shown very useful for the studies of crystal growth kinetics.
Shape Transformation of Plastic Crystals under the Effect of Surface Energy. Adamantane in Temperature Gradient Conditions
Authors: Iwanov D. , Nenow D.
Published: January 2007

The spontaneous transformation of a polycrystal into a single crystal at high temperatures is observed with adamantane samples. Since the plastic crystal phase at such temperatures is not elastically strained it is concluded that the process is due to the surplus of surface energy in the system. The spontaneous transformation to the equilibrium form of crystals under temperature gradient conditions is investigated. The effect is established both of the surface energy and the shape of the isothermic surfaces.
Thermally Stimulated Discharge Current Studies in Thin Films of Polyacrylamide
Authors: Rao K. V. Satyanarayana , Rao S. Sreepathi , Rao U. V. Subba
Published: January 2007

TSDC of pure polyacrylamide films of thickness 22 μ grown by isothermal solution growth technique has been studied as a function of polarizing field and polarizing temperature at a constant heating rate of 0.09 K s1 In these studies only one TSDC peak was observed and the temperature corresponding to this peak was found to be independent of polarizing field strength but dependent on polarizing temperature. The activation energies, relaxation parameters and charge associated with the peak were evaluated. The origin of TSDC is discussed.
X‐ray and RHEED Characterization of Ge Ions‐Implanted Si Crystals Subjected to Pulsed‐Laser Annealing
Authors: Auleytner J. , Fiedorowicz H. , Furmanik Z. , Patron Z. , Regiński K.
Published: January 2007

In the experiment a (111) oriented silicon plate was subjected to implantation by 80 keV Ge ions. Then the pulsed‐laser annealing of this sample was carried out by using neodymium laser to form several areas irradiated with different light power. The effectiveness of the annealing has been analyzed by means of transmission X‐ray topography, double crystal X‐ray spectrometry, and reflection high energy electron diffraction. These three methods have appeared to be complementary and very effective in studying the spatial homogeneity of annealed areas, their state of annealing, and the damage in the surface layers.
Compressibility in the Tetragonal Phase of AgInS2 From the X‐ray Diffraction Data under High Pressure
Authors: Orlova N. S. , Turtsevich G. A. , Kochkarik O. E. , Bodnar I. V.
Published: January 2007

The lattice parameters a and c as well as the compressibilities for different directions in the AgInS2 chalopyrite‐type compound are determined as a function of pressure up to 5 GPa using a powder X‐ray technique under high pressure. It is found that the compressibility is anisotropic, with compressibility along the tetragonal c‐axis (𝓏c) being smaller than that along the a‐axis (𝓏a). It is shown that as pressure rises the axial ratio c/a increases and as a result the tetragonal distortion δ = 2 ‐ c/a reduces.
Contribution to High‐temperature Modifications of the Anhydrous Alkaline Earth Metal Sulfates
Authors: Bimberg R. , Illner N. , Puhlmann P. W.
Published: January 2007

Large synthetic crystals of alkaline earth metal fluorides, especially fluorite crystals, contain sometimes unknown small inclusions of hexagonal form. Samples of these crystals were investigated by microscope, X‐ray, and microprobe analysis to identify the included small crystals. Optical behaviour of these inclusions, morphology, chemical composition, and the reaction with water allow their interpretation as high‐temperature modifications of the anhydrous water soluble alkaline earth metal sulfates, partly transformed to the corresponding sulfides.
Size Distribution Analysis of Needle‐Shaped Crystals
Authors: Nývlt Jaroslav , Žáček Stanislav
Published: January 2007

Two methods of measurement of the crystal size distribution of needle‐shaped carystals are compared: direct measurement of a number of crystals on a microphotograph, which is rather tedious and time consuming, and the photosedimetric method which is quicker, easy to perform but not so suitable for not isometric crystals. A methods is described that brings results of both of these methods into agreement. The method has been verified on strongly anisometric particles of calcium sulphate.
Defect Structure in Te‐doped GaAs single Crystals after Plastic Deformation (I). Twins and Stacking Faults
Authors: Paufler Peter , Wagner Gerald , Grosse Katrin
Published: January 2007

At temperatures above the brittle‐to‐ductile transition (490 °C) in Te‐doped GaAs three types of predominant defect configurations have been observed after uniaxial compression along a [001] direction: (i) twins and stacking faults (500 … 520 °C), (ii) slip zones of dislocations (≈ 550 °C) and (iii) dislocation cells (580 … 590 °C). In Part I quantitative details of the appearance of twins and stacking faults are given. Most frequently found were 30° partials in twins and stacking faults.
X‐ray Molecular and Crystal Structure Study of the Fe(II) Complex Containing 1,10‐Phenanthroline and Saccharin: [Fe(C12H8N2)3] (C6H4COSO2N)2 · 4 H2O
Authors: Jianmin Li , Jing Wei , Xingtao Wu , Nianyong Zhu , Yifan Zheng
Published: January 2007

X‐ray molecular and crystal structure of the [Fe(C12H8N2)3] (C6H4COSO2N)2 · 4 H2O is reported. In the complex, the Fe atom is bonded to the six nitrogen atoms with a distorted octahedral stereochemistry.
Crystallization Kinetics of Silicalite‐1: Use of Tetrapropylammonium Bromide and Chloride as Templates
Authors: Çulfaz A. , Gündüz U. , Orbey H.
Published: January 2007

Silicalite‐1, the aluminum‐free end number of the ZSM‐5 zeolites, was synthesized from a batch composition of 3.25 Na2O · 40.0 SiO2 · 552 H2O · 2.00 TPA by using tetrapropylammonium bromide (TPA‐Br) or chloride (TPA‐Cl) as templates in the temperature range of 100 to 175 °C in a batch system. Conversion of silica in the starting batch composition into silicalite‐1 in the product was followed quantitatively. The activation energies of nucleation and crystallization were determined as 37.2 and 66.5 kJ/mol, respectively. The use of TPA‐Cl as the template instead of TPA‐Br results in longer induction period for crystallization to start and a larger crystal size in product.
Crystal and Molecular Structure of 1‐Cyano, 4(Trans‐1′, N‐Pentyl‐Cyclohexyl‐4′‐Carboxy)‐Benzene, ECH‐5
Authors: Ibrahim I. H. , El‐Shora A. I. , Abdeen A. M. , Aly N. F.
Published: January 2007

The crystals of ECH‐5 belong to the triclinic system, the space group is P1 with two molecules in the unit cell. The lattice dimensions are a = 9.153(2), b = 16.848(3), c = 5.770(4) Å, α = 97.26(5), β = 93.68(4), γ = 93.07(2)°. The structure was solved by direct methods and was refined using block diagonal least squares method to a final value of R0 = 0.083 for 1787 observed reflections. The cyclohexane ring is chair. Torsion angles calculations showed that the middle part of the molecule is bent. The molecules are packed in head to tail manner, and they are arranged nearly parallel to each other.
A Metastable Mg11Sm Phase Obtained by Rapid Solidification
Authors: Budurov Stojan
Published: January 2007

Molten Mg‐Sm alloys with a Sm concentration of 4.93, 6.86, and 8.35 at. % were rapidly soldified with the aid of a shock wave gun device. Investigations of the obtained splats were performed with the aid of DSC, X‐ray analysis, and metallography. Rapid soldification of the eutectic MgSm8.35 alloy forms a new Im3m‐ type phase.
Anomalous Up‐and‐Down Variation of Positron Lifetime Near Tc in High‐temperature Superconductors
Authors: Zhang D. M. , Tang C. Q. , Gen T. , Li G. Y.
Published: January 2007

The temperature dependence of the positron lifetimes in the polycrystalline high Tc superconducting YBaCuO and BiSrCaCuO and the non‐superconducting YBaCuO have been investigated by using the position lifetime technique. It is found from the experiments that there is an evident temperature dependence for the two kinds of superconducting samples but no temperature dependence for non‐superconducting sample. It is important that the anomalous up‐and‐down variation of positron lifetime near Tc has been observed in the measured superconducting samples. We suggest that this strange temperature dependence of the positron lifetimes near TC may result from some changes induced by the phase transition.
Resistance and Current Density Studies on Plasma Sprayed Coatings of Bi(Pb)CaSrCuO Superconducting Materials
Authors: Rao D. Mangapathi , Mishra D. , Venudhar Y. C.
Published: January 2007

Plasma spraying is a potential technique for forming flexible tapes from brittle high Tc oxides. It is possible to obtain superconducting Bi(Pb)CaSrCuO coating by suitable heat treatment schedule after spraying. In an effort to get maximum transport current densities (Jc) of the coating, the content of lead and sintering time have been optimised. A Jc value of 200 Amp/cm2 is obtained in Bi1.4Pb0.6 · Ca2Sr1.9Cu3Oy specimen coated on silver sprayed Fe[(Ag)/Fe] substrate. Remarkable improvement in Jc values up to 694 Amp/cm2 is obtained in the same specimen coated on Ca2Sr1.9Cu3Oy sprayed Fe[Ca2Sr1.9Cu3Oy)/Fe] substrate. The observed decrease in Jc(B) curves with increase in magnetic field shows the presence of weak coupling between the grains.
Thermally Stimulated Discharge Currents in Pure and Doped Sodium Yttrium Fluoride
Authors: Shareefuddin Md. , Chary M. Narasimha
Published: January 2007

The thermally stimulated discharge currents (TSDC) of pure NaYF4, and NaYF4 doped with 0.5 mole% Sm (in the form of SmF3) have been studied as function of polarizing temperature and polarizing field strength at a constant heating rate (β) = 0.05 Ks−1. The activation energies, relaxation parameters and charge were evaluated. The origin of TSDC spectra in NaYF4: Sm is attributed to space charge polarization. Whereas both dipolar and space charge process are found to operate in NaYF4 sample.
Mathematical Description of Strongly Nonlinear Pressure Dependence of Phase Transition Temperatures
Authors: Rein C. , Demus D.
Published: January 2007

In order to describe mathematically the pressure dependence of phase transition temperatures we have derived an equation using the following assumption:
i. The transition enthalpy ΔtH = const.
ii. The transition volume ΔtV depends on the pressure p according to:

The modified Simon‐Glatzel‐equation
T = T0(1 + p/b)a exp (cp)
allows to calculate the transition temperatures T also in cases of strongly non‐linear relations.
Calcium Oxalate Monohydrate Crystal Growth
Authors: Costa‐Bauzá A. , Grases F. , Söhnel O.
Published: January 2007

The growth rate of calcium oxalate monohydrate seed representing aggregates of highly irregular crystals from solutions of the stoichiometric composition with I = 100 mol m−3 in the range of supersaturation Δc = 0.056 to 0.353 mol m−3 was measured at 37 °C by the constant composition method. The crystal growth rate decreased during the initial period of experiment, then reached a value constant over a considerable time and later increased again. The initial decrease of the growth rate resulted from crystal perfection whereas the later increase was caused by formation of new crystals by secondary nucleation. The supersaturation dependence of the kinetic growth rate satisfied the power law with the growth order equal to 2 and 4 at supersaturations lower and higher than about Δc = 0.150 mol m−3, respectively.
Optical Phonons and Chemical Bonding in TlSbS2, TlSbSe2, and Tl3SbS3 Crystals
Authors: Syrbu N. N. , Krasovsky V. T. , Grincheshen I. N.
Published: January 2007

The optical phonons at k = 0 of TlSbS2, TlSbSe2, and Tl3SbS3 have been investigated by infrared reflectivity measurements from 50 to 4000 cm−1 at 300 K. The factor group analysis of vibrational modes of TlSbS2 and Tl3SbS3 crystal lattices has been made. The dielectric constant dispersion for E ‖ a and E ‖ b has been determined by classical dispersion relations. The Szigeti effective charges, the Born dynamic effective charge, and the Tl, Sb, S (Se) relative ion charges were calculated in dependence on the polarization of the incident light.
Etch Pit Density Distributions in Undoped and Doped GaAs Single Crystals
Authors: Moravec F. , Štěpánek B. , Šestáková V.
Published: January 2007

The undoped and doped (Si, N, In) GaAs single crystals are grown by horizontal Bridgman technique. The etch pit density (EPD) profiles were measured in transverse direction for each crystal. It was found that the shape of EPD profiles differs in dependence on the used dopant.
Thermoelectric Power of Polycrystalline Sb2Te3 Films
Authors: Patel N. G. , Patel P. G.
Published: January 2007

Polycrystalline stochiometric films of Sb2Te3 with different thickness were prepared on glass substrates by a flash evaporation technique at constant substrate temperature of 423 K. The thermoelectric power of these films was determined by measuring integrally the developed thermo — e.m.f. at different temperature differences between the hot and cold ends. The thermoelectric power of Sb2Te3 films was determined as a function of the temperature and thickness of the films. It was found that the Fermi level becomes pinned at higher temperatures. The values of γ, E0, and A parameters were determined as functions of the thickness of the films. The dependence of the thermoelectric power on the reciprocal thickness of the films was explained on the basis of the grain size effect.
Positron Annihilation Study on the Thermal Fatigue in a Die Steel
Authors: Tang C. Q. , Li X. Z. , Shi Z. H.
Published: January 2007

Samples of 5Cr2NiMoVSi die steel which underwent thermal fatigue with different fatigue cycles have been studied by using microhardness and positron lifetime measurements. It is found that the microhardness and the positron lifetime parameters increase and decrease alternatively with increasing the number of the fatigue cycles. The experimental results reveal that the fatigue strain, the dynamical recovery, and recrystallization and the precipitation are main causes of variation of the defects in the process of thermal fatigue.
Two‐Phonon Combination Mode Spectra of AgGaS2
Authors: Neumann H. , Sobotta H. , Moise E. , Treser E. , Krämer V.
Published: January 2007

Absorption spectra of (001)‐oriented AgGaS2 single crystals are measured in the wavenumber range from 400 to 900 cm−1. The spectra exhibit 12 structures due to two‐phonon combination modes which can be all interpreted as sum modes of zone‐centre phonons. Possible frequencies for the B1 and A2 modes are discussed. The results obtained are compared with second‐order Raman spectra of the compound.