bluuebunny/crossref_metadata_2025 huggingface dataset:
Twinning of Crystals due to Differences between the Most Favourable Symmetric and Energetic Structural Arrangements, Part II
Authors: Krafczyk S. , Jacobi H. , Follner H.
Published: January 2007

Twins and oriented intergrowths are often caused by structural instabilities. A conflict arises between the highest symmetric and the most favourable energetic structural arrangement. A necessary condition for twin growth is the presence of lattice pseudosymmetries. This was shown with two additional examples, maleic acid and 3,5‐dimethylbenzoic acid. Both substances are known practically only as twins. Using lattice‐energy calculations, energetic arrangements that are more favourable were found in both cases. These structures explain the transition that can exist between the twin crystal parts.
The Thermal Decomposition of Polyhalite K2SO4 · MgSO4 · 2 CaSO4 · 2 H2O
Authors: Fischer S. , Voigt W. , Köhnke K.
Published: January 2007

The thermal decomposition of polyhalite (K2SO4 · MgSO4 · 2 CaSO4 · 2H2O) was investigated by DSC/TG and X‐ray powder diffraction. The decomposition of the polyhalite starts at 285 °C in releasing the crystal water within one step. Simultaneously the decomposition of the polyhalite into anhydrite and two solid solutions of the compositions K2SO4 · 1.76 MgSO4 · 0.24 CaSO4 and K2SO4 · 0.64 MgSO4 · 1.36 CaSO4 is taking place. The mechanism of decomposition runs through K2SO4 · MgSO4 CaSO4. This phase reacts immediately to the solid solutions, mentioned above.
The Double Salts Cd(C6H5COO)2 · CdCl2 and Cd(C6H5COO)2 · CdBr2
Authors: Balarew Christo , Stefanova Rumiana
Published: January 2007

The systems Cd(C6H5COO)2CdCl2H2O and Cd(C6H5COO) 2CdBr2H2O have been studied at 25 °C. Formation of the double salts Cd(C6H5COO)2 · CdCl2 and Cd(C6H5COO)2 · CdBr2(1:1:0) has been established and their chemical individuality has been confirmed by chemical, X‐ray, and DT‐analyses.

Proceeding from data on the structure of Cd(C6H5COO)2 · 2 H2O and the composition of the 1:1:0 double salts as well as using Pauling's rules for the most probable spacial disposition of the ions, the crystal structure type of the double salts obtained are predicted.
Diamond Synthesis by Thermal Plasma Chemical Vapour Deposition (TP‐CVD)
Authors: Presia M. , Heider Th. , Schleicher L. , Nutsch G.
Published: January 2007

This paper reviews results about diamond synthesis by high‐temperature pyrolysis of methane in a H2/Ar‐plasma. By means of a modified direct‐current (DC) plasma torch with an arc power of 4–8 kW diamond growth rates in the order of about 70 μm/h were obtained. Diamond films grown on unscrached single‐crystalline silicon have a diameter of about 8 mm. Scanning electron microscopy (SEM), X‐ray diffractometry (XRD), and Raman scattering spectroscopy have been used to analyse diamond films characterized by a transition of a crystalline diamond centre to an amorphous random region by passing a fine‐crystalline region. In the film centre (100) planes with an average size of about 25 μm were made out by SEM.
In Situ Observation of Step Evolution on {100} Face of KH2PO4 Crystal in Solution by Atomic Force Microscopy (AFM)
Authors: Krasiński Mariusz J. , Rolandi Ranieri
Published: January 2007

In situ observation of the surface morphology of {100} face of Potassium Dihydrogen Phosphate (KDP) crystals growing in solution was made with the use of Atomic Force Microscope. The slight movement of the steps connected with regeneration of the crystal surface has been detected for very low supersaturation. The height of the elementary steps has been established.
Observation of Ferromagnetic Domains in NdFeB Single Crystals by Photoelectron Microscopy
Authors: Wang J. Y. , Romanowicz J. , Maundschau M. , Sun D. L. , Chen H. C.
Published: January 2007

This paper reports on the successful growth of NdFeB single crystals. Ferromagnetic domains of these crystals are observed by photoelectron microscopy. Thc domains may disappear and re‐appear during the experiments. A possible mechanism of the contrast formation of the domains is proposed and discussed.
Alkali Defect Centers and Current Density Peaks in Quartz Sweeping
Authors: Iliescu B. , Vedda A. , Spinolo G.
Published: January 2007

The paper presents the current density peaks during the heating‐up phase for different kind of quartzes: clear natural from Brazil, smoky natural, and synthetic quartz from Sawyer Research Product (Electronic and Premium Q), Toyo, romanian and polish ones, and compares the phenomenon in vacuum and in air for the same applied electric field and gives a model, with which the process could be described.
Coexistent Phases and their Electrical and Structural Behaviour in the Ternary Re/Mo/O System
Authors: Doerr M. , Feller J. , Oppermann H.
Published: January 2007

In order to complete and improve phase diagrams of transition metal oxides the existence and properties of compounds in the Re/Mo/O system have been investigated. Single crystalline solid solutions Re1‐xMoxO2 (0 < x < 0.37) and Mo1‐yReyO2 (0 < y < 0.42) were prepared by Solid State Reactions and Chemical Transport Reactions (CTR) and characterized by means of X‐ray‐diffraction, ICP‐AES, and EPMA. In addition, it was shown that the trioxides Re1‐xMoxO3 or Mo1‐yReyO3 respectively, do not prove a distinct solubility. First results on Re‐doped Magneli phases of Mo are also discussed. There were found two series of solid solutions Mo4‐zRezO11 (0 < z < 0.40) which derive from γ‐Mo4O11 and η‐Mo4O11. The other Magneli phases did not show a significant Re content. Using X‐ray diffraction, AFM and optical microscopy the structure and morphology of single crystals has been studied. It was steated that the dioxide solid solutions were very homogeneous and structural phase transitions depending on x or y did not occur. That is in good agreement with measurements of electrical conductivity σ in the temperature range from 20 K to 300 K in which the samples showed the behaviour of metals with lattice defects. The Magneli phases Mo8O23 and Mo9O26 turned out to be “narrow gap semiconductors” in the low temperature range with activation energies of less than 0.1 eV. The γ‐Mo4 O11‐ and γ‐Mo4O11 crystals, the pure and Re‐doped ones, were found as metallic conductors at higher temperatures and below a transition temperature they show a semiconductive behaviour.
Polymeric Additives: Effects on Crystallization of Hydroxyapatite Scales
Authors: Doherty W. O. S. , Crees O. L. , Senogles E.
Published: January 2007

The effects of some commercial polymeric additives on the nucleation (induction period), crystal growth, and morphology of hydroxyapatite precipitated from pure solutions of the lattice ions have been examined. The inhibitory capacities of these additives for hydroxyapatite scale formed from whole juice samples under conditions similar to those operating in sugar mills have also been determined. The results show that poly(aspartic acid) with Mw of 5700 is the most effective scale inhibitor.
Optical Absorption Spectra of Czochralski‐grown (Dy1‐xGdx)3O12Ga5O12 and Dy3(Ga1‐yAly)5O12 Garnets Relating Unstable Spiral‐shape Growth
Authors: Kimura H. , Numazawa T. , Sato M. , Kochurikhin V. V. , Shimamura K. , Fukuda T.
Published: January 2007

Optical absorption has been measured from 700 to 1300 nm for garnet single crystals by substituting Dy or Ga for Gd or Al of Dy3Ga5O12 grown by the Czochralski method, and a suppression of unstable spiral‐shape growth on Dy3Ga5O12 by the substitution was discussed relating the absorption spectra. The total absorption in the single crystals at the wavelength corresponding to the radiation from Ir crucible was decreased relatively with the increase of Gd or Al content. The decrease of this absorption in the single crystals is one of the causes to suppress the unstable spiral‐shape growth.
Piezoelectric and Elastic Properties of Orthorhombic LiH2PO3 and LiH2PO4
Authors: Haussühl S.
Published: January 2007

Single crystals of LiH2PO3 and LiH2PO4, both of space group symmetry Pna21, with dimensions up to 40 mm were grown from aqueous solutions by controlled evaporation. Pyroelectric, dielectric, piezoelectric, elastic and thermoelastic properties were studied by standard methods. The static piezoelectric constants d333 exceed d111 of α‐quartz by only a factor 2. The pyroectric effects reach 3 times and 7 times, respectively, that of tourmaline. The mean elastic stiffness of the phosphite is 13% smaller than that of the phosphate, a phenomenon also observed in the corresponding sodium and potassium salts.
Electrical Characterization of Irradiation plus Annealing – induced VAsZnGa Pairs in p‐type GaAs (Zn) Crystals
Authors: Glinchuk K. D. , Prokhorovich A. V.
Published: January 2007

Effect of fast electron irradiation (E =2.2 Mev, ϕc = 1 × 1016 el/cm2) and subsequent annealings (T = 150 to 350 °C, t = 10 to 600 min) of zinc‐doped p‐type GaAs crystals on the formation and dissociation of VAsZnGa, pairs is studied. An analysis of the formation and dissociation kinetics of VAsZnGa pairs permitted to find the diffusion coefficient of radiation‐induced arsenic vacancies D(D = 1.5 × 10−18, 1 × 10−17 and 5 × 10−17 cm2/s at 150, 175 and 200 °C accordingly), their migration energy ϵm(ϵm = 1.1 eV), the binding energy of VAsZnGa, pairs ϵb(ϵb = 0.5 eV), and also their dissociation energy ϵd(ϵd = 1.6 eV).
Some Physical Properties of Ga2Se Single Crystals
Authors: Gamal G. A. , Nagat A. T. , Nassary M. M. , Abou‐Alwafa A. M.
Published: January 2007

Measurements of the electrical conductivity, Hall effect, thermnoelectric power were carried out in a wide temperature range (from about 170 to 475 K) for Ga2Se compound grown in single crystalline form. The present investigation revealed unusual observations in the Hall effect and the scattering mechanisms of the charge carriers indicating that Ga2Se is not a simple semiconductor. Also it showed that Ga2Se has a relatively high value of the thermoelectric power. A lot of physical parameters were deduced in the present study.
Gettering Properties of Praseodymium in GaAs, In0.53Ga0.47As, and InP Grown by Liquid Phase Epitaxy
Authors: Jiang Gwo‐Cherng
Published: January 2007

The incorporation of praseodymium (Pr) into GaAs, In0.53Ga0.47As, and InP during liquid‐phase epitaxy were investigated by double crystal x‐ray diffraction, Hall effect, low temperature photoluminescence (PL) measurements. The lattice mismatch slightly vary with Pr concentration in the growth melts. Examinations of the electrical property illustrate that the lower carriers concentrations and a higher mobilities are obtain from Pr‐doped epilayers than undoped sample (In0.53Ga0.47As and InP). The PL spectra (15‐K) show that the intensity of the impurity related peaks decreases and the near‐band‐to‐band luminescence intensity increase. They also reveal that the impurities are gettered by Pr ions during LPE growth. Thus, for the purpose of purification, proper amount of Pr in the growth melts is suggested. No intra‐4f‐shell transition line is observed from the Pr‐doped GaAs, In0.53Ga0.47As, and InP layers.
Sb2Te3 Single Crystals Doped with Chromium Atoms
Authors: Lošťák P. , Drašar Č. , Navrátil J. , Beneš L.
Published: January 2007

Chromium‐doped Sb2Te3 single crystals were prepared from elements of semiconductor purity using a modified Bridgman method. The samples of these crystals were characterized by means of X‐ray diffraction analysis, measurements of the reflectivity in the plasma resonance frequency range ωp, of the Hall constant RH and electrical conductivity σ. It was found that the incorporation of Cr atoms into the Sb2Te3 crystal lattice reduces the volume of the unit cell, whereas the values of ωp and RH (i.e. the concentration of holes) remain unaltered and the values of σ decrease with increasing chromium content. This effect is qualitatively explained by an interaction of incorporated Cr atoms with antisite defects of Sb2Te3 crystal lattice. The In (RHσ) vs. In T dependences show that the dominant mechanism of scattering of free charge carriers in the studied crystals is the scattering by acoustic phonons; the presence of chromium atoms increases the scattering rate by ionized impurities.
Growth and Properties of the Organometallic Nonlinear Optical Crystal: Semicarbazide Cadmium Chloride (SCCC)
Authors: Wang B. G.
Published: January 2007

Semicarbazide cadmium chloride (SCCC) is an organometallic nonlinear optical crystal. Preparation and crystal growth of SCCC have been studied, thermal and IR spectral properties of the crystal are characterized. Investigations of the molecular and crystal structures show that there is a large charge‐transfer bridge in the molecule, and that the crystal has a distorted polyhedrally‐coordinated structure. The relations between the structures and NLO effects of complex crystals have been discussed, and optimization of structures of organometallic NLO crystals are suggested.
Structural and Spectral Studies of 2‐(3,4,5‐trimethoxyphenyl)‐Benzothiazole
Authors: İde S. , Öztaş S. G. , Ancin N. , Tüzün M.
Published: January 2007

2‐(3,4,5‐trimethoxyphenyl)‐benzothiazole, C16H15NO3S was obtained by condensation of 2‐aminobenzenethiol with 3,4,5‐trimethoxybenzoldehyde. The structure of the title compound was indicated by IR, 1H‐NMR, UV spectra and confirmed by an X‐ray analysis. In the molecule the trimethoxyphenyl and benzothiazole groups are connected by a CC bond of 1.478(6) Å. The trimethoxyphenyl except a methoxy group and the benzothiazole group are nearly planar. The dihedral angle between these planes is 8.5(9)°.
Rietveld Refinement of the Crystal Structure of Nickel Hexaamina Perchlorate and ‐Tetrafluorborate
Authors: Lutoslawska‐Rogóż J. , Mucha D. , Hodorowicz S. A.
Published: January 2007

Room‐temperature phases of nickel hexamina perchlorate (NHP) and nickel hexaamina tetrafluorborate (NHT) were analysed by means of X‐ray powder diffractometry. Both compounds crystallize in the cubic system (Fm3m space group) with cell parameters:a= 11.4689 Å for NHP anda= 11.2692 Å for NHT structure, respectively. The crystal structures of these compounds were refined using Rietveld method.
Theoretical Approach to the Deformation‐induced Luminescence in Metals
Authors: Chandra B. P. , Khan M. S. , Singh Seema R. , Ansari M. H.
Published: January 2007

The present paper reports the mechanoluminescence (ML) produced during fracture of metals. The mechanism of ML in metals is based on the generation of holes during the decay of mobile dislocations on the surface and subsequent electron‐hole radiative recombination. The following equation is derived for the transient ML intensity of the fracto‐induced ML in metals
equation image
.

The above equation shows that I should be maximum for a particular value of time t. For β 〉 α,
equation image
.

This equation shows that I should decrease exponentially with time. For the fracto‐induced ML in metals, tM and Im may be expressed by the following equations
equation image
.

The spectroscopy of ML in metals is also discussed. A good correlation is found between the theoretical and experimentals results.
Structural and Thermal Characterization of Zeolite Type Y Modified by Ion Exchange with Zn, Cd, and Hg Cations
Authors: Sarbak Z.
Published: January 2007

The object of our studies was zeolite NaY and its Zn2+‐, Cd2+‐ and Hg2+ modifications obtained by ion‐exchange method. Influence of the above cations on the crystalline structure of zeolite type Y and its thermal stability has been shown on the grounds of X‐ray diffraction, differential thermal analysis, and infrared spectroscopic measurements.
Phase Transition Energy of the Short Period Basic Polytypes of CdI2
Authors: Khan Momeen M. Y.
Published: January 2007

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

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

In a ternary mixture of two liquid crystals and a non‐mesomorphic chiral dopant an intermediate state with an unusual texture was found between the cholesteric and the SA phase which could be identified as a separate twisted mesophase. The reflection wavelength of this mesophase does not change with temperature whereas the transmission of unpolarized light decreases from 50 to 20%.

The experimental findings point to the existence of a twisted grain boundary phase.
Growth of GaAs Crystals by VGF at Different As Source Temperatures
Authors: Frank C. , Hein K. , Hannig C. , Gärtner G.
Published: January 2007

The influence of the As source temperature on the properties of undoped 〈100〉 orientated GaAs crystals during VGF crystal growth was investigated in the range of TAs = 600 to 631 °C. The crystal morphology has shown significant differences. A monocrystalline growth is observed in the range of TAs = 607 to 620 °C. The EPD values are in the range of 103 cm−2 irrespective of the preset temperature of the As source. A decrease in the As source temperature from 620 °C to 607 °C will result in a reduced concentration of the intrinsic defect EL2 from 0.8. 1016 cm−3 to 0.6. 1016 cm−3.

Der Einfluß der As Quellentemperatur auf die Eigenschaften von undotierten, <100>‐orientierten GaAs Kristallen bei der VGF Züchtung wurde im Bereich von TAs = 600–631 °C untersucht. Die Kristallmorphologie wies dabei deutliche Unterschiede auf. Bei TAs von 607–620 °C wird einkristallines Wachstum beobachtet. Die EPD Werte liegen dabei im Bereich von 103 cm−2 unabhängig von der eingestellten Temperatur der As‐Quelle. Mit Verringerung der As Quellentemperatur von 620 °C auf 607 °C tritt eine Reduzierung der Konzentration des Eigendefektes EL2 von 0,8. 1016 cm−3 auf 0,6. 1016 cm−3 ein.
Crystallization of K2SO4 in presence of Cr2O Ions
Authors: Nývlt Jaroslav , Žáček Stanislav
Published: January 2007

Bichromate ions exhibit a strong effect on crystallization of potassium sulphate. Solubilites in the three‐component system given in the literature for 25 and 40 °C were recalculated for the region from 20 to 70 °C and bichromate concentrations up to 10%. Metastable zone width measurements in solutions containing up to 3% of the admixture served for an estimate of the kinetics of nucleation. Batch crystallization experiments and MSMPR experiments yielded kinetic data of nucleation and crystal growth. Computer simulations of the crystal shape indicated the effect of admixture on the crystal growth of individual faces.

Die Kristallisation von K2SO4 wird stark durch die Anwesenheit von Cr2O beeinflußt. Die Löslichkeit in diesem Dreikomponentensystem wurde an Hand von Literaturangaben für 25 und 40 °C auf das Intervall 20 bis 70 °C und bis 10% der Beimischung rechnerisch erweitert. Messungen der Breite des metastabilen Gebietes in Lösungen mit einem Gehalt bis 3% der Beimischung dienten zur Bestimmung der Keimbildungskinetik. Diskontinuierliche und kontinuierliche Kristallisationsversuche lieferten kinetische Daten der Keimbildung und des Kristallwachstums. Die Kristalltracht des K2SO4 wurde mit dem Rechner simuliert, was die Abschätzung der Einwirkung der Beimischung auf die Wachstumsgeschwindigkeit einzelner Flächen ermöglicht.
Structure and Texture of Nickel‐Molybdenum Catalysts on Alumina Support Modified with Fluoride or Chloride Ions
Authors: Lewandowski M. , Sarbak Z.
Published: January 2007

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

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

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

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

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

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

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

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

The investigation aims to analyse the influence of different kinds of thermal treating on the structure of martensite.

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

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

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

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

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

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

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

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

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

Growth of spherulitic crystals of iron tartrate by controlled diffusion in sodium metasilicate gels has been described. Infrared spectroscopic, thermogravimetric and elemental analysis have been conducted to characterize the crystals. The results are interpreted and explained.
On the Interface Shape of Semitransparent Crystals obtained by the Bridgman Method
Authors: Nicoarǎ Irina , Pusztai A. , Nicolov Mirela
Published: January 2007

The effect of the pulling rate and of the furnace configuration on the interface shape in semitransparent crystals grown by the vertical Bridgman method are studied by finite—element analysis.
Stabilization Effect of Zr and Ti Additions on the Ageing Characteristics of Al‐1 wt% Si Alloy Through a Creep Study
Authors: Deaf G. H. , Beshai M. H. N. , El Khalek A. M. Abd , Graiss G. , Kenawy M. A.
Published: January 2007

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

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

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

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

Microhardness testing of three different planes of natural apophyllite crystals is reported. Variation of Vicker's microhardness value Hv with applied load ranging from 10–100 g indicates two distinct regions. In the low load region (10–70 g) Hv increases with load till it attains maximum value and then decreases thereafter. This variation is explained qualitatively in terms of depth of penetration of the indentor. Variation of orientation of the indentor w.r.t. each of the (100) and (111) planes indicates microhardness anisotropy.
New technique for crystal growth and Phase Transition in TlInS2 Crystals
Authors: Gamal G. A.
Published: January 2007

New technique for crystal growth was designed in the present work. The electrical conductivity and Hall effect of the TInS2 single crystals, grown by this technique, were measured in the temperature range 150–500 K. From the measurements, the conductivity type, the energy gap, ionization energy of the impurity level, Hall mobility and carrier concentration were determined. Also the measurements revealed a presence of phase transition in the crystal at 189 and 220 K.
Crystallization of an organic intercalation compound: cholic acid
Authors: Kalkura S. Narayana , Kanakavel M. , Ramasamy P.
Published: January 2007

Crystals of cholic acid have been grown in silica and tetramethoxy silane gels. Crystals grew with different morphology and Leisegang rings were also seen in some cases. Crystals were analyzed by X‐ray, IR and microhardness studies. The grown crystals were found to be monohydrate and the hardness of the crystals were found to decrease with increase of load.
Hydrothermal Synthesis and Morphology of Thomsonite and Edingtonite
Authors: Ghobarkar H. , Schäf O.
Published: January 2007

The hydrothermal treatment of different glasses of the composition 2 Na2O–8 CaO–10 Al2O3– 20 SiO2 and 2 BaO–2 Al2O3–6 SiO2 at one kilobar pressure in a temperature‐range between 80 °C and 230 °C lead to the formation of the zeolite‐minerals thomsonite (orthorhombic symmetry space‐group Pbmn, a = 13.05 Å, b = 13.09 Å and c = 13.22 Å), and edingtonite (orthorhombic symmetry, space‐group: P2,2,2, a = 9.55 Å, b = 9.67 Å and c = 6.52 Å). Under the chosen hydrothermal conditions both mineral phases are formed in the whole temperature interval.
Understanding and Controlling the Morphology of ZnO Crystallites under Hydrothermal Conditions
Authors: Wang B. G. , Shi E. W. , Zhong W. Z.
Published: January 2007

The morphological features of ZnO crystallites influenced by solution basicity under hydrothermal conditions have been studied from the standpoint of the incorporation of the growth units. A crystal chemistry approach is developed to understand and thus to control a desirable morphology of the crystallites. The effects of the additive OH− on the crystal morphology of ZnO crystallites are qualitatively but satisfactorily explained by a mechanism considering two aspects: (1) solution structures and the structural forms of growth units under a certain growth condition, i.e. the interactions between the solvent molecules and the growth units; and (2) the influence of the solvent molecules or additives on growth interfaces, particularly on two polar faces of ZnO crystallites in terms of the inhibition or promotion of the incorporation of various growth units depending on the solution basicity. Since the incorporation rates of the growth units are different on positive and negative polar faces, the relative growth rates of these faces are different and thus lead to the habit modifications. The approach clearly demonstrates that the hindrance of crystal growth is a consequence of surface adsorption processes.
Temperature Induced Surface Transitions in Liquid Crystal Planar‐Tilted Hybrid Cells
Authors: Moldovan R. , Frunza S. , Beica T. , Tintaru M. , Ghiordanescu V.
Published: January 2007

Temperature induced surface transitions in liquid crystal hybrid cells with asymmetrical anchoring, planar to one surface and tilted to the other, are experimentally studied. The results are theoretically explained by an elastic theory and the resulting values for the effective splay‐bend elastic constant for a given liquid crystal, as well as the parameters characterising the anchoring on the boundary surface with tilted anchoring are compared with data from previous experiments, with good agreement.
Crystalloluminescence produced during the micro‐fracture of growing crystallites
Authors: Chandra B. P. , Verma P. K. , Ansari M. H.
Published: January 2007

The present paper reports the theory of crystalloluminescence (CRL) produced during the micro‐fracture of growing crystallites. Surface charges may be developed during the micre‐fracture of crystallites due to several processes like piezoelectrification, movement of charged dislocations, barodiffusion of defects near the moving crack etc. The surface charges may be neutralized by the movement of charge carriers produced due to the dielectric breakdown near the surface of crystallites and consequently the recombination luminescence may occur. Considering the basic concepts of crystallization from the supersaturated solution, expressions are derived which are able to explain satisfactorily the temporal, thermal, spectral concentration and other characteristics of the CRL. It is shown that the induction period for crystal nucleation, lifetime of supersaturation, size of crystallites and time constant for the relaxation of charges on the newly created surfaces may be determined from the CRL measurements.
Phosphate Composition of Precipitates from Urine‐like Liquors
Authors: Grases F. , Villacampa A. I. , Söhnel O. , Königsberger E. , May P. M.
Published: January 2007

The composition of the solid phases precipitating from urine‐like liquors has been determined at 37°C over the pH range between 6 and 8 for solutions with varying amounts of magnesium, citrate, oxalate and ammonium ions. At pH ⩽7 hydroxyapatite appeared, either alone or, depending on the magnesium ion concentration, in a mixture with brushite. Stravite and calcium phosphates precipitated at pH ⩾ 7.5. No other phosphate solids were observed to precipitate from these urine‐like liquors under physiological conditions. No influence on the nature of the solid phase was exerted by citrate, oxalate or ammonium ions. The variation of solid phase composition caused by changing solution composition is ascribed to kinetic rather than thermodynamic factors.
Effects of Acceptor Modification on Charge Transfer in Crystals of Donor‐Acceptor Systems of TTF
Authors: Salmerón‐valverde A. , Robles‐Martínez J. G. , García‐serrano J. , Gómez R. , Ridaura R. , Quintana M. , Zehe A.
Published: January 2007

The degree of charge transfer has been determined in six TTF‐fluorene derivative charge transfer complexes, using IR and Raman vibrational spectroscopies. It has been found that changes of the intermolecular electronic distribution is strongly influenced by the presence of the dicyanomethylene group, by the increase of the nitro groups, as well as by the symmetry of the acceptor.
Growth and Optical Characterization of CdI2 Single Crystals
Authors: Ajithkumar G. , Ittyachen M. A. , Chaudhary S. K. , Unnikrishnan N. V.
Published: January 2007

Single crystals of CdI2 were grown by employing the horizontal zone refining method. Emission spectra of these crystals were recorded at room temperature and liquid nitrogen temperature. Various emission parameters such as optical gain coefficient, lifetime, gain, stimulated emission cross section were evaluated for the various emission components. The results show high gain at low temperature whereas very low value at rmm temperature. This has been explained by invoking the existence of self trapped excitons in the crystal.
Growth and Properties of Trigonal Aluminium Gallium Orthophosphate Single Crystals Al1‐xGaxPO4
Authors: Xia Hai‐Rui , Qin Zi‐Kai , Yuan Wu , Liu Shi‐Fang , Zou Zhi‐Qiang , Han Jian‐Ru
Published: January 2007

The new piezoelectric solid solution aluminium gallium orthophosphate single crystals have been successfully developed for the first time in our laboratory by hydrothermal method. It has been demonstrated that these crystals are homogeneous, and isomorphous with AIPO4 and GaPO4. The solid solution crystals Al1‐xGaxPO4 are easy to grown and have better optical quality than those of AlPO4 crystals under the same conditions. A phase transition temperature Tα‐β is 587 ± 3 °C for x = 0.12. Cell parameters, and elastic, piezoelectric, and dielectric constants are given.
Growth and Characterization of Na2CaGe6O14 Single Crystals
Authors: Takeda Hiroaki , Uecker Reinhard , Kumatoriya Makoto , Shimamura Kiyoshi , Reiche Peter , Fukuda Tsuguo
Published: January 2007

Transparent, crack‐free Na2CaGe6O14 (NCG) single crystals were successfully grown using the Czcchralski technique. The largest crystal had 30 mm in total length and 18 mm in maximal diameter. Best crystal quality was achieved under low temperature gradient arrangement. The crystal structure of NCG has been refined from single crystal X‐ray diffraction data. Some piezoelectric properties of NCG are reported.