bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Formation of Thick Sector Boundaries by Appearance and Disappearance of Faces of Crystals
Authors: Szurgot Marian
Published: January 2007

Wide sector boundaries revealed in KBC crystals by chemical etching have been observed and analysed. It was established that the boundaries represent sectors of small faces appearing and vanishing in the habit during crystal growth. This nature of thick boundaries has been confirmed by the analysis of values of relative growth velocities of faces with respect to the critical velocities governing the presence of faces on growing crystals.
The Influence of Interstitials and Growth Conditions on the X‐Ray Colorability of Synthetic Quartz Crystals
Authors: Bernhardt Hj.
Published: January 2007

The saturation colorability of quartz crystals depends not only on the contamination of the material but also on the regarded growth sector. But even in the same sector the colorability varies locally. Investigations of crystals with induced growth striations and defined local growth rate showed that the dependence of the colorability on the growth conditions is very complex. The growth rate to colorability characteristics may have positive or negative slopes regarding e.g. —x‐or z‐sections. Optical investigations of —x‐sections prove that under certain circumstances light and/or dark striations may occur or even uncolorable regions may be observed, althought the contamination is sure. We explain this by the interaction of the coloration centres with interstitials. That effect might be of importance for the evaluation of the impurity by means of the coloration of natural or synthetic quartz crystals.
Stability Determinant of Anisotropic Phases
Authors: Sirota N. N.
Published: January 2007

The thermodynamic stability of crystal determinant D) and nonstability Dn st(14) of the fourteenth order, their adiabatic and corresponding isodynamical coefficients are discussed.
Dielectric Properties of Beta Barium Borate and Potassium Pentaborate Single Crystals
Authors: Raja C. Ramachandra , Gobinathan R. , Gnanam F. D.
Published: January 2007

Single crystals of beta barium borate and potassium pentaborate (commonly known as β‐BaB2O4 or BBO and KB5O8. 4 H2O or KB5) were grown by high and low temperature solution growth methods, respectively. The dielectric constant and loss tangent were determined as a function of temperature. Frequency response of the dielectric constant and tan δ have been studied over a frequency range of 0.1 −100 kHz; it is found that both the dielectric constant and tan δ decrease with increase in frequency for both crystals. The dielectric constant and tan δ are found to increase with increase in temperature for both the crystals. Further, the dielectric constant and tan δ measured on different orientations of the grown crystals reveal the anisotropic nature of the crystals.
The Discovery of the Diffraction of X‐rays in Crystals — A Historical Review
Authors: Hildebrandt G.
Published: January 2007

The history of the discovery of X‐ray diffraction in crystals and its first sequels are reported; the life of M. v. Laue, the discoverer and founder of a first basic theory, and of P. P. Ewald, who contributed to the discovery and to later developments of the theory, are shortly described.
A Statistical Thermodynamics and Growth Restrictions (STGR) Model of Polytypism with Special Reference to Zinc Sulfide
Authors: Ahmad Shandar , Wahab M. A.
Published: January 2007

A model to explain polytypism based upon classical statistics and the idea of minimum sandwiches of basic phases has been developed. Presence of two or more phases under suitable thermodynamic conditions and restrictions imposed by statistical, structural, and growth factors have been elaborated. A new statistical approach is used and a criterion to find most probable polytypes of a compound has been evolved. Logical implications of the model are found in good agreement with the experimental data.
The Hydrothermal Effect on Crystal Development and Electrical Conductivity of Li2CO3
Authors: Ghobarkar Habib , Schäf Oliver
Published: January 2007

Lithiumcarbonat was treated hydrothermally in the range of temperature from 80 °C to 600 °C. The Li2CO3‐crystals of the starting material were monoclinic with the unit cell a = 8.39 Å, b = 5.00 Å, c = 6.21 Å, β = 114.5° and the space group C2/c (Zemann). During the increase of temperature the habit of the Li2CO3‐crystals changed in the ranges of higher temperatures that they could be described as pseudocubic. In parallel with this development the electrical conductivity of the crystals also changed.
Growth and Characterisation of Pure and Nickel‐doped Strontium Tartrate Tetrahydrate Single Crystals
Authors: Rethinam F. Jesu , Oli D. Arivu , Ramasamy S. , Ramasamy P.
Published: January 2007

Strontium tartrate tetrahydrate single crystals doped with nickel have been grown in silica gel. The grown crystals have been characterized by X‐ray, atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), and etching technique.
Growth Morphology and Structure Peculiarities of Superthin Titanium Films
Authors: Mikhailov I. F. , Borisova S. S. , Fomina L. P. , Babenko I. N. , Melnik N. N. , Pudonin F. A.
Published: January 2007

Superthin titanium films of 0.3 to 2 nm thickness, prepared by radio‐frequency sputtering, have been studied by modern X‐ray methods, such as reflectometry, fluorescent analysis and grasing‐beam structural analysis. Two simple models were used to describe early stages of film growth. It has been shown that the thinnest titanium films were the TiO2 islands with an equal height. Thicker films could be described as bilayers Ti/TiO2. The films became continuous already near 1.5 nm effective thickness.
High‐temperature Raman Investigations of Arsenic Vapour
Authors: Herms M. , Wunderwald U. , Irmer G.
Published: January 2007

Raman spectra of arsenic vapour were measured at temperatures up to 1210 K. The intensity ratio of the vibrational modes was used to determine the partial pressure ratio of As2 and As4.

The data obtained exhibit discrepancies to existing theoretically predicted values. The reason for these differences is yet unclear.
Magnesium Sulphite Hexahydrate Supersaturated Solutions Stability
Authors: Söhnel O. , Rieger A.
Published: January 2007

Wet purification of crude MgSO3 · 6 H2O obtained at flue gases desulphurization is based on its dissolution, separation of solid ash followed by crystallization of a clear supersaturated solution. The stability of supersaturated solutions during ash separation represents a requisite condition for realization of this process. The stability of agitated supersaturated solutions containing from 5 to 8 wt% of MgSO3 is assessed in the temperature range from 80° to 95 °C based on experimentally determined induction period of crystallization, tind, and desupersaturation curves. Time necessary for complete dissolution of MgSO3 · 6 H2O at the studied conditions, tD, is also determined. A plot of (tind – tD) versus solution initial supersaturation facilitates selection of suitable processing conditions for the wet purification.
Electron Microscopy and X‐ray Study of the Growth of FeCr2S4 Spinel Single Crystals by Chemical Vapour Transport
Authors: Volkov V. V. , Van Heurck C. , Van Landuyt J. , Amelinckx S. , Zhukov E. G. , Polulyak E. S. , Novotortsev V. M.
Published: January 2007

The growth features of FeCr2S4 spinel single crystals prepared by chemical vapour transport were studied by means of scanning electron microscopy, transmission electron microscopy, high resolution electron microscopy, electron diffraction and X‐ray analysis. Our results indicate that the epitaxial growth of the new phases FeCr7S12 and FeCr8S12, both based on the NiAs structure, can essentially inhibit the growth of large FeCr2S4 spinel single crystals in the octahedral habit. The new phases are fully characterised and the effects of defect ordering in these new phases are also reported.
Formation of Hydrogen‐Bonding Adduct between 1‐Phyenyl‐2‐Amino Pyrimidine and Vaniline, C17H13N3O2
Authors: Farag I. S. Ahmed , Gad A. M. , El‐Shabiny A. M. , Rybakov V. B.
Published: January 2007

The adduct compound was prepared by condensation of equimolar quantities of analar vaniline and 1‐phenyl‐2‐amino pyrimidine in absolute ethyl alcohol. Prismatic crystals were obtained with the crystallographic data: a = 12.901 (6), b = 19.297 (9), c = 6.828 (3) Å, γ = 102.67 (2)°, V = 1657.9 Å3, Z = 4, F.W. = 291.31, Dx = 1.17 g/cm3, space group P2/n, R = 0.038 and Rw = 0.036.

The intensity data were collected on an Enraf Nonius CAD‐4 computer controlled diffractometer using MoKα radiation. The structure was solved by direct method and refined by full matrix least‐squares using anisotropic temperature factor of all atoms, except for hydrogen ones, which were treated isotropically. A full discussion was given to explain: a) the occurrence of the condensation process between the OH‐group of vaniline and the heterocyclic N‐atom in position 5 of the pyrimidine cycle and b) why this condensation does not take place between the amino‐group of the pyrimidine compound and the aldehydic group of vaniline to give a Schiff base.
Vibrational Studies of Magnesium Hydrogen Phosphate‐ and Barium Hydrogen Phosphate Crystals
Authors: Kolandaivel P. , Parthipan R. , Selvasekarapandian S.
Published: January 2007

Magnesium hydrogen phosphate and Barium hydrogen phosphate crystals were grown in the presence of sodium meta silicate (sol‐gel method). Raman and IR spectra were measured for the above crystals. Vibrational assignments were made for both the crystals. The large shift of the stretching and bending modes of water from the free state values indicates the different hydrogen bonds strenghts present in the magnesium hydrogen phosphate crystals.
Structural Aspects of Dehydration Processes in Rubidium‐, Potassium‐ and Sodium p‐Nitrosophenolates
Authors: Milart P. , Kapturkiewicz‐Kowal E. , Borzecka‐Prokop B.
Published: January 2007

Rubidium p‐nitrosophenolate has been prepared and characterized by means of IR spectroscopy and XPD methods. Differences of dehydration processes of the rubidium salt and relative potassium‐ and sodium p‐nitrosophenolates have been detected by DTA/TG studies and discussed in terms of crystallochemically inequivalent types of water molecules in these salts.
The influence of HF on the incorporation of silicon into the erionite‐like AlPO4‐17 molecular sieve
Authors: Lohse U. , Jancke K. , Löffler E. , Schaller T.
Published: January 2007

The synthesis of SAPO‐17 with high silicon content (up to 18 weight‐%) succeeded with the addition of HF to the reaction mixtures. The characterization of the samples with chemical analysis, XRD, and adsorption measurements show the incorporation of silicon into tetrahedrally coordinated framework positions. Spectroscopic methods (IR, 19F MAS NMR) demonstrate the presence of fluorine in the as‐synthesized samples. The effect of the fluorine consists in (i) the improvement of the silicon incorporation into framwork positions, (ii) the stabilization of the as‐synthesized samples and (iii) the charge compensation of the template ion by F−.
Stoichiometric defects and volume diffusion in epitaxial PbTe‐SnTe multilayers
Authors: Fedorov A. G. , Galkina E. V. , Mikhailov I. F. , Shpakovskaya L. P.
Published: January 2007

The effect of annealing on multilayer structures based on epitaxial layers of PbTe‐SnTe was investigated by X‐ray diffraction profile changes. Decrease of satellite reflections intensity and conversion of pattern asymmetry were found. Profiles of interplanar distance and electron density deviations were determined by solving both the direct problem (numerical computation of Takagi‐Taupin equations) and the inverse problem (optimisation task) according to the average lattise model. Computation showed the presence of interlayer area of PbSnTe composition containing up to 8% of stoichiometric vacancy type defects between PbTe and SnTe layers. Two diffusion mechanisms are proposed: “fast” diffusion connected with occupation of stoichiometry defects and “slow” substitutional diffusion.
X‐ray determination of thermal lattice expansion of CuSi2 + xP3 (x = 1, 2) at elevated temperatures
Authors: Bhikshamaiah G. , Omar M. S. , Suryanarayana S. V.
Published: January 2007

CuSi2P3 is a semiconductor having sphalerite structure with the space group F33m with random distribution of the copper and silicon atoms on the cation sites. Silicon is soluble in CuSi2P3 upto 3 moles to form CuSi2 + xP3 (x = 1, 2, 3) compounds in single phase. In continuation of our work on thermal expansion of ternary semiconductors, CuSi3P3 crystals have been grown by a modified Bridgman method. Using a Unicam high temperature camera, the precision lattice parameter and the coefficient of thermal expansion (CTE) of CuSi3P3 at various high temperatures have been evaluated from X‐ray diffraction data. It has been found that the lattice parameter increases non‐linearly while the coefficient of thermal expansion increases linearly with temperature. The results on thermal expansion of various semiconductors have been discussed in terms of their ionicities.
A rietveld study of the cation substitution between uvarovite and yttrium‐aluminum synthetic garnets, obtained by sol‐gel method
Authors: Carda J. , Tena M. A. , Monros G. , Esteve V. , Reventos M. M. , Amigo J. M.
Published: January 2007

A series of synthetic garnets solid solutions is compositions between Y3Al2Al3O12 (Y‐Al garnet) (YAG) and Ca3Cr2Si3O12 (uvarovite) was synthesized using the sol‐gel method. The expected general formula is (CaxY1‐x)3 (CrxAl1‐x)2 (SixAl1‐x)3O12 where x = 0 to x = 1.

The cation distribution in dodecahedral, octahedral and tetrahedral sites and bond distances in these synthetic garnets were determined using the Rietveld method. It shows the incomplete substitution in small sites. The smaller site the smaller substitution there is.
The preparation of calcium oxalate dihydrate crystals
Authors: Doherty W. O. S. , Crees O. L. , Senogles E.
Published: January 2007

Two simple related methods for exclusively preparing well‐developed tetragonal bipyramidal crystals of calcium oxalate dihydrate at moderate supersaturations and at ambient temperature are reported. These crystals have an average length of 5.7–7.2 μm and are easy to wash and filter. One of the methods is suitable for studies of the kinetics of spontaneous precipitation and crystal morphology of the oxalate in the presence and absence of additives. A tentative mechanism is given to account for the sole formation of this particular hydrate.

At 70 °C a mixture of the monohydrate and dihydrate phase were formed with various crystal shapes and sizes. These phases were also identified in the presence of sucrose at this temperature, although some of the crystals contained tetragonal habit as obtained at ambient temperature.
The crystal and molecular structure of three homologue 1,4‐dialkanoyloxy‐biphenyls (SYM‐n)
Authors: Thyen W. , Zugenmaier P.
Published: January 2007

The three homologue compounds with the general formula CnH2n+1COOC6H4C6H4OOCCnH2n+1 (SYM‐n) crystallize in the following space groups: SYM‐1: triclinic, P1, a = 7.400(6), b = 9.227(3), c = 10.579(3) Å, α = 85.97(3), β = 89.09(3), γ = 71.47(3)°; SYM‐2; monoclinic, P21/c, a = 11.712(7), b = 5.648(1), c = 12.408(6), Å, β = 103.84(3)°; SYM‐5: triclinic, P1, a = 5.505(4), b = 8.342(8), c = 24.79(2) Å, α = 86.67(3), β = 85.45(6), γ = 71.74(7)°.

The structures have been solved by direct methods and refined to R = 0.075, 0.061 and 0.053, respectively. The packing arrangements show a layer‐like structure. The layers are almost separated for SYM‐1 as well as for SYM‐2 and interdigitated for the structure of SYM‐5.
Elastic properties of the pseudocubic perovskite (CsCd(NO2)3
Authors: Haussühl S.
Published: January 2007

Multidomain crystals of CsCd(No2)3 grown from aqueous solutions at about 310 K exhibit a quasi‐cubic symmetry in their thermal expansion, elastic and thermoelastic properties. The elastic constants of the low‐temperature multidomain state resemble the behaviour of stable cubic perovskites almost quantitatively. This suggests that the trigonal low‐temperature phase of CsCd(NO2)3 possesses a quasi‐cubic symmetry. The transition from the trigonal low‐temperature phase into the cubic high‐temperature phase at about 464 K is accompanied by a small deformation of about 10−4 and a lambda‐type variation of the thermal expansion.
Computer‐aided evaluation of kossel patterns obtained from quasicrystals
Authors: Weber S. , Schetelich Ch. , Geist V.
Published: January 2007

For the evaluation of Kossel experiments on quasicrystals such as the decagonal phase of AlCoNi or AlCoCuSi a computer program called KOQUA has been written, which allows to simulate Kossel patterns of two‐ and three‐dimensional quasicrystals as well as of every conventional crystal system. In some examples the application of the program is demonstrated.
The growth of high‐quality MCT films by MBE using in‐situ ellipsometry
Authors: Svitashev K. K. , Dvoretsky S. A. , Sidorov Yu. G. , Shvets V. A. , Mardezhov A. S. , Nis I. E. , Varavin V. S. , Liberman V. , Remesnik V. G.
Published: January 2007

The ellipsometry and RHEED study of high‐quality MCT films grown on (112)‐ and (130) CdTe and GaAs by MBE was carried out. The dependence of the ellipsometric parameter ψ on MCT composition is evaluated. It was shown that such parameters as growth rate, the surface roughness, initial substrate temperature, and film composition may be measured by the in‐situ ellipsometry. The appearance of surface roughness was observed in the initial stage of MCT growth under various compositions (xCdTe = 0 ÷ 0.4). The further growth at optimum conditions leads to the smoothing of the surface and supplies us with high‐quality MCT films. The concentration, mobility, and life time of carriers in MCT films were respectively: n = 1.8 × 1014 ÷ 8.2 × 1015 cm−3, μn = 44000 ÷ 370000 cm2 V−1 s−1, τn = 40 ÷ 220 ns; p = 1.8 × 1015 ÷ 8.4 × 1015 cm−3, μp = 215 ÷ 284 cm2 V−1 s−1, τp = 12 ÷ 20 ns.
Defect studies in CuBIIIC chalcopyrite compounds using the ion channeling technique
Authors: Neumann H.
Published: January 2007

Based on simple approximations the backscattering minimum yield is estimated for axial ion channeling in perfect crystals of six CuBIIICchalcopyrite compounds. The results obtained for CuInSe2are compared with experimental channeling spectra. Point defect concentrations up to about 1021cm−3are estimated for CuInSe2single crystals grown by the vertical Bridgman method. A simple power law is found for the fluence dependence of the damage density in oxygen implanted CuInSe2single crystals.
Characterization of dislocations in a LiNbO3 single crystal grown by micro pulling down method
Authors: Yoon D. H. , Yonenaga I. , Fukuda T.
Published: January 2007

LiNbO3 single crystals grown by the micro pulling down (μ‐PD) method have been revealed to be as free of dislocations and subgrain boundaries up to 500 μm in diameter. On the other hand, μ‐PD LiNbO3 single crystals grown along the x‐axis in diameter of 800 μm were observed to be dislocated due to the size effect of crystal. The Burgers vectors of dislocations were determined to be [2201], [1011], and [0111] by X‐ray topography.
Li–Zn ferrites with nonmagnetic additives
Authors: Rezlescu N. , Rezlescu E. , Craus M. L. , Pasnicu C.
Published: January 2007

The authors investigated the effect of small additive amounts of non‐magnetic ions as Na1+, Ca2+, Zr2+, Sb3+ and binary or ternary combinations of these ions on some physical properties of the (Li0.5Fe0.5)0.6Zn0.4Fe2O4 ferrite used in high frequency. It was found that by the segregation of these additives on the grain boundaries, the grain growth is diminished and much higher sintered densities are obtained in several cases, though not all. We established that additives such as Na2O, CaO, ZrO2 enhance the rate of sintering, giving a speedy start to the sintering process. All additives improve the electrical resistivity due to insulating intergranular layers generated by segregation of additives.
Growth of corundum single crystals by the top‐seeded solution growth technique (TSSG)
Authors: Watanabe Koichi
Published: January 2007

Single crystals of corundum were grown by the top‐seeded solution growth technique from a cryolite, Na3AlF6, solvent. The relationship between the growth rate (mg/h) of a crystal and the temperature difference (= supersaturation) or the rotation rate of a seed crystal was investigated, and optimum growth conditions for obtaining single crystals with good quality are discussed.
Crystal structure of a dehydroabietate derivative
Authors: Padha Naresh , Singh Vinod , Subramaniun E. , Gupta K. K. , Taneja S. C. , Goswami K. N.
Published: January 2007

The crystal structure of methyl‐16, nor‐5‐hydroxy‐6,7,15‐trioxo dehydroabietate has been determined from three‐dimensional X‐ray diffraction data. The compound crystallizes in the orthorhombic space group P21212 with unit cell parameters a = 19.226(3) Å, b = 11.075(3) Å, c = 8.375(2) Å, Z = 4, V = 1783.3(7) Å3, d0 = 1.36 gcm−3. The gross structure was determined by direct methods which on refinement yielded a final value of R index as 0.038. Ring A is a chair, ring B an envelope whereas the ring C adopts a strictly planar conformation. The rings A and B are trans fused. The ester group at C4 is cis fused to methyl carbon C15 whereas another methyl carbon C18 and oxo O(15) of the isopropyl group at C13 are rotated to positions 0.107(3) Å and 0.179(2) Å out of the plane of ring C.
Crystal and molecular structure of the chiral compound 4–(2–methylbutyloxy)phenyl–4–(2‐propenyloxy)‐benzoate, C21H24O4
Authors: Kaeding A. , Zugenmaier P.
Published: January 2007

The enantiomeric [(S)‐(–)‐MBP3B] and the racemic form [(±)‐MBP3B] of the title compound with the formula C3H5O–C6H4–CO2–C6H4–OC5H11were studied by single crystal analysis at room temperature.

(S)‐(–)‐MBP3B crystallizes in the orthorhombic space group P212121witha= 7.835(3) Å,b= 11.093(6) Å,c= 44.820(3) Å and 8 molecules per unit cell. The structure was determined from 966 reflections with intensities > 3σ. The refinement with isotropic temperature factors leads toR= 0.094.

The crystals of the racemic form are monoclinic, space group P21/a witha= 7.899(5) Å,b= 11.046(6) Å,c= 22.845(12) Å, β = 99.28(3)°,Z= 4.1236 diffractometer data (I> 3σ) were refined by least‐squares methods with anisotropic temperature factors for the non‐H atoms toR= 0.070.

The packing arrangement for both forms shows a layer‐like structure with very similar packing coefficients,k= 0.7085 for the pure enantiomer andk= 0.7014 for the racemic form.
Growth and characterization of mixed neodymium praseodymium oxalatze decahydrate crystals in silica gel
Authors: Joseph Cyriak , Varghese George , Ittyachen M. A.
Published: January 2007

Mixed single crystals of neodymium praseodymium oxalate decahydrate were grown from silica gel by controlled reaction of rare earth nitrates with oxalic acid. The crystals were characterized using X‐ray powder diffraction and optical absorption studies.
Influence of synthesis and postgrowth treatment conditions on the structural homogeneity of YBa2Cu3Ox single crystals
Authors: Ivanova T. I. , Yu. Vlasov M. , Moshkin S. V. , Frank‐kamenetskaya O. V. , Kuzmina M. A.
Published: January 2007

The effect of synthesis and postgrowth treatment (by annealing at various temperatures and partial oxygen pressures) conditions on structural homogeneity of YBa2Cu3Ox single crystals has been studied. The obtaining of single crystals with both high oxygen content and high critical temperatures Tc has been optimized. The wide range of postgrowth treatment conditions proposed allows to receive single crystals with given oxygen content from 6.2 to 7.0.
Dielectric characteristics of neodymium heptamolybdate crystals grown by gel encapsulation technique
Authors: Bhat Sushma , Khosa S. K. , Kotru Dr. P. N. , Tandon R. P.
Published: January 2007

Results obtained from the dielectric studies of neodymium heptamolybdate crystals grown in the system Nd(NO3)3 –MoO3 –NH4OH– HNO3 —Na2SiO3 by gel encapsulation technique are presented. The variation of dielectric constant (ε′), dielectric loss (tanδ) and conductivity (σ) with frequency at different temperatures is studied. The dielectric constant of the material increases sharply, attains a peak value and then decreases rapidly, as material's temperature rises from room temperature to higher degrees. The temperature at which the peak value is attained is the transition temperature of the material. Dielectric loss (tan δ) follows almost a similar behaviour. The conductivity (σ) is also found to be temperature‐and frequency‐dependent. This sharp rise in ε′ is attributed to the contribution from space charge polarization. Theoretically obtained data using the expression ε′ = a0 + a1 T2 and —In σ = a + b(T — T0)2 for T < T0) fits very well with the experimentally obtained data indicating that space charge polarization increases as some power of temperature larger than one.
Growth and Characterisation of Gel‐grown Lead(II)Chloride and Lead(II)Bromide Single Crystals
Authors: Sagayaraj P. , Sivanesan S. , Gobinathan R.
Published: January 2007

Single crystals of pure and doped lead(II)chloride and lead(II)bromide were grown by gel technique employing a modified two‐stage chemical reaction. Methods to minimise the predomination of needle morphology during the growth of these crystals have been investigated and the results are discussed. The grown crystals were characterised by optical transmission spectrum. Undoped and monovalent cation (K+, Na+, Cu+, Ag+ and Hg+) doped crystals of PbCl2 and PbBr2 were subjected to d.c. electrical conductivity studies. Using the log σT versus T−1 plot, the activation energies for the migration of anion vacancies in lead(II)halides are calculated. They are found to be less for the doped crystals than those of undoped ones.
Synthesis and Structure Study of the Complex [Cu2 (μ–C2O4) (C10H8N2)2(H2O)2] (C6H4COSO2N)2 Crystal Structure Containing Cu (II) Bipy Oxalato and Saccharin
Authors: Jianmin Li , Jingzhen Sun , Pengcheng Chen , Xintao Wu
Published: January 2007

The title compound has been synthesized and its crystal structure determined at room temperature. MW = 927.86, monoclinic, space group P21/c, Z = 2, a = 9.283(1) Å, b = 16.239(2) Å, c = 12.209(1) Å, β = 99.848(9)°. The crystal structure consists of repeated [Cu2(μ–C2O4)(C10H8N2)2 · (H2O)2]2 cations and non‐coordinated saccharin anions. Each copper ion is in a square pyrimidal environment with two oxalate oxygen and two bipyridine nitrogen atoms as a base and one water molecule at the apex. The two copper ions are bridged by oxalato and the distance is 5.138 Å.
Intergrowth Structures of YBA2Cu3Ox Single Crystals with Oxygen Inhomogeneity
Authors: Ivanova T. I. , Frank‐Kamenetskaya O. V. , Drits V. A. , Kastowsky M. , Bradaczek H.
Published: January 2007

The diffraction pattern simulation of four YBa2Cu3Ox single crystals with inhomogeneous distribution was successfully carried out on the base of the theory of X‐ray diffraction by disordered interstratified structures. The specific feature of their two‐component irregular mixed‐layered structures is the total segregation of layers with various oxygen content that led to the formation of so‐called intergrowth structures. The concentration of admixture layers varied from 10 to 40% while oxygen content difference within the crystal ranged from 0.5 to 0.3. In one of the crystals the fluctutations of layer heights corresponded to oxygen variation from 6.2 to 7.0.
Twins in GaAs Crystals Grown by the Vertical Gradient Freeze Technique
Authors: Koh H. J. , Fukuda T. , Choi M. H. , Park I. S.
Published: January 2007

The growth of facets and the generation of twins on <100> VGF (vertical gradient freeze technique) grown GaAs were investigated using DSL (diluted Sirtl‐like etchant with light) photoetching and transmission X‐ray topography. Due to the polarity of the (111) plane in GaAs, As facets are larger and more irregular than Ga facets and twins always occur on As facets. Twins are initiated at the change of boundary condition which is affected by temperature gradient and crucible shape. The mechanism of twin generation is explained by considering the edge concavity at the solid‐liquid interface and the supercooling required for initial nucleation of a facet. Twins are more often produced in Si‐doped crystals than undoped ones due to the constitutional supercooling.
Comparative Dielectric Investigations on Nematic Liquid Crystals with Aerosil
Authors: Tschierske S. , Yaroshchuk O. V. , Kresse H.
Published: January 2007

Dielectric measurements on a nematic room temperature mixture and the mixture with 20% aerosil were carried out. Addition of aerosil results in a small increase of the clearing temperature and in increasing relaxation frequency for the reorientation around the short molecular axis. The results are interpreted as orientation effect of the nematic sample at the fractal aerosil.
Modified Growth of Mercuric Iodide Crystals from the Vapour Phase
Authors: Li Associate Pro. Zheng‐Hui , Li Wei‐Tang , Liu Jun , Zhu Shi‐Fu , Zhao Bei‐Jun , Yuan Hong , Xu Hua‐Peng
Published: January 2007

The Hgl2 single crystal with shiny natural crystal planes, low density of dislocation, and 350 g in weight has been grown by a new technique of modified vapoir phase located point method. The perfection and nuclear spectroscopic performance of the grown crystals are also studied.
Growth and Character of the Transition Spectrum of Nd‐doped K2La(NO3)5 · 2 H2O Crystals
Authors: Fang C. S. , Zhuo H. S. , Yang Z. H. , Fang L. , Sherwood J. N.
Published: January 2007

Potassium lanthanum nitrate dihydrate (KLN) is a new nonlinear optical crystal. An Nd‐doped potassium lanthanum nitrate (KLNN), was grown. As the first on this crystal and its characters of growth, thermal, spectral, and nonlinear optic properties is reported. KLNN crystal will be a useful material in frequency conversion of generating blue‐green laser.
Study of the Growth Morphology of Ammonium Oxalate Monohydrate Crystals Obtained from Aqueous Solutions
Authors: Mielniczek‐Brzóska E. , Sangwal K.
Published: January 2007

The experimental results of the growth morphology of ammonium oxalate monohydrate [(NH4)2C2O4 · H2O; AO] single crystals obtained from aqueous solutions at 30 and 40 °C and supersaturation up to 9% are presented. The observations are compared with the theoretical morphology predicted by PBC analysis and Braivais‐Donnay‐Harker law.
Classification of Mechanoluminescence
Authors: Chandra B. P. , Rathore A. S.
Published: January 2007

On the basis of the processes involved in inducing luminescence, mechanoluminescence (ML) may be classified into different types, such as: (i) piezo‐electrification‐induced fracto ML, (ii) defective‐phase piezo‐electrification‐induced fracto ML, (iii) charged dislocation electrification‐induced fracto ML, (iv) baro diffusion electrification‐induced fracto ML, (v) chemically‐induced fracto ML, (vi) thermally stimulated fracto ML, (vii) incandescent fracto ML, (viii) stress perturbation‐induced fracto ML, (ix) thermal excitation‐induced fracto ML, (x) mechanically excited ML, (xi) deep trap‐induced fracto ML, (xii) dislocation mechanical interaction‐induced plastico ML, (xiii) dislocation electrostatic interaction‐induced plastico ML, (xiv) charged dislocation electrification‐induced plastico ML, (xv) thermal excitation‐induced plastico ML, (xvi) dislocation mechanical interaction‐induced elastico ML, (xvii) dislocation electrostatic interaction‐induced elastico ML, (xviii) thermal excitation‐induced elastico ML, (xix) electrically induced tribo ML, (xx) chemically‐induced tribo ML, (xix) electrically induced tribo ML, (xx) chemically‐induced tribo ML, and (xxi) thermally‐induced tribo ML. It is expected that the processes involving dislocation electrostatic interaction‐induced elastico ML and thermal excitation‐induced elastico ML may provide suitable ML materials in future.
On the Crystal Structure of Rare Earth Complexes with 2‐Ethylhexyl Phosphoric Acids
Authors: Bozukov L. N. , Milanova M. M. , Todorovsky D. S.
Published: January 2007

The crystal structure of the complexes of some rare‐earths (RE = La, Nd, Pr and Er) with bis‐ and mono‐(2‐ethylhexyl)phosphoric acids were studied by using the X‐ray powder diffraction. The results show that for all RE investigated, the complexes of the diester crystrallize in orthorombic symmetry and cell parameters have been determined. The complexes of the monoester have been found to be nanocrystalline or amorphous.
Trap Level Characterization of Synthetic Quartz
Authors: Gandhi Y. H. , Vyas P. R. , Joshi T. R.
Published: January 2007

Thermoluminescene (TL) of synthetic quartz specimens under different physical conditions is investigated. An analysis for one of the prominent glow peaks has been done using the peak shape method. Further, on the basis of extracted trap level spectroscopic information, the results are explained. It is found that with different physical conditions characteristics of trapping level changes systematically.
Convective Temperature Fluctuations in Liquid Gallium in Dependence on Static and Rotating Magnetic Fields
Authors: Dold P. , Benz K. W.
Published: January 2007

The influence of static axial, static transversal, and rotating magnetic fields on convective temperature fluctuations in liquid gallium (temperature range around 800 °C, Prandtl number 2.5 · 10−3) has been investigated. For a Rayleigh number of 6.3 · 10−5 (ΔT = 10°C, h = 50 mm), convective temperature fluctuations with peak to peak values of 3 °C have been measured. Depending on the strength, the frequency, and the configuration of the field, they could be eliminated to ΔT < 0.01 °C (static axial field of 182 mT), damped to a nearly periodic state with 0.1 °C amplitudes (static transversal field of 45 mT), or reduced to 0.03 °C oscillations by applying a rotating field.
Thermal Hysteresis Accompanying Incommensurate‐Commensurate Phase Transition in Mixed Crystals (K1‐xCsx)2ZnCl4
Authors: Ahn H. Y. , Jeong S. Y. , Jang M. S. , Chung W. S.
Published: January 2007

The mixed crystal (K1‐xCsx)2ZnCl4 with x = 0, 0.001, 0.01, 0.1, and 0.2 with optical quality has been grown by the Czochralski method. Using the Atomic Absorption Spectroscopy (AAS) and Energy Dispersive Spectroscopy (EDS), we determined the amount of Cs ion included in the mixed crystal. By using of DTA and DSC, we observed the change of Tc and Ti. The thermal hysteresis in the dielectric constants show strong dependence on the thermal process and on the amount of impurity which are explained by the influence of the thermal process and impurity, respectively on the creation, annihilation, and growth of discommensuration (DC).
Interactions between YBa2Cu3O7‐x and K2Co3
Authors: Vassilev G. P.
Published: January 2007

The interactions between YBa2Cu3O7‐x and K2CO3 have been studied using thermochemical methods, isothermal annealing of diffusion pairs, optical microscopy, X‐ray diffraction, and microprobe analyses. The experiments have shown existence of solubility of YBa2Cu3O7‐x or its constituents in both solid and liquid K2CO3. The barium ions are preferably dissolved in K2CO3, whereas potassium cations do not enter massively into the bulk of the YBa2Cu3O7‐x‐phase. A eutectic‐type phase diagram is supposed for the system K2CO3–YBa2Cu3O7‐x.

The so called “green phase” Y2BaCuO5 and a K–Cu–O compound have been found in the contact zone at 813 °C while a “black phase” layer with nominal composition Y1.6Cu2.8O5.4 has grown at 707 °C.
Monte Carlo Simulation of Clustering in Solutions
Authors: Nýavlt Jaroslav
Published: January 2007

A simple Monte Carlo simulation has been used for the study of clusters formation in solutions. The dependence of induction periods on supersaturation as well as the obtained clusters size distribution are in qualitative accord with the theoretical expectations.
Optical Investigation of Defects in p‐type CuInSe2Single Crystals
Authors: Neumann H. , Jones P. A. , Sobotta H. , Hörig W. , Tomlinson R. D. , Yakushev M. V.
Published: January 2007

Optical absorption spectra in the photon energy range from 0.03 to 1.1 eV and photoreflectance spectra in the range of the fundamental edge are measured on p‐type CuInSe2single crystals. Besides a dominant contribution to the absorption coefficient due to intervalence band transitions below about 0.75 eV the spectra revealed five additional structures that can be ascribed to defect induced optical transitions with characteristic energies between 0.48 and 0.72 eV. Based on a comparison of the near‐edge optical absorption and photoreflectance spectra a shallow defect (donor or acceptor) with an ionisation energy of about 46 meV was identified.
Magnetic Moment and Susceptibility Measurements of Mixed Rare Earth Oxalate Crystals
Authors: Joseph Cyriac , Varghese George , Ittyachen M. A.
Published: January 2007

The growth of double rare earth oxalate crystals with a general chemical formula AB(C2O4)3 · 10 H2O (where A and H are Nd, Pr and Sm) is reported. The variation of the magnetic moment of these crystals with an external field is studied and the magnetic susceptibility and the effective magnetic moment are calculated. The observed effective magnetic moment of the crystals are in good agreement with those calculated on theoretical grounds.
The Nature of One‐sided Intergrowths on (001) of Triclinic Centrosymmetric K2Cr2O7
Authors: Heide G. , Follner H.
Published: January 2007

Systematic composite crystal growth can arise when larger crystals of the same type exhibit oriented intergrowth. One example of this is potassium dichromate (P1) which SHUBNIKOV first described in 1912. In highly supersaturated solutions, a one‐sided roughening of its crystals occurs on (001). Electron micrographs show that this is due to the growth of platelet‐shaped crystals. Optical and X‐ray methods as well as electron channeling and BACK‐KIKUCHI diffraction patterns have shown that the growths are predominantly parallel intergrowths, about 10% of which are twins according to [010].
Crystal Structure of Sarcosine Cadmium Chloride
Authors: Krishnakumar R. V. , Rameela M. P. , Natarajan S.
Published: January 2007

Single crystals of sarcosine cadmium chloride were crystallised from a saturated aqueous solution containing stoichiomeric amounts of sarcosine and cadmium chloride, in 1:1 proportion. The intensity data were collected using a CAD‐4 diffractometer with graphite monochromated MoKα, radiation. The crystal data are as follows: a = 6.916(1) Å, b = 13.855(3) Å, c = 7.981(1) Å, V = 764.1 Å · F.W. = 272.4, dexpt = 2.39 g · cm−3, dcalc = 2.368 g · cm−3, Z = 4 and the space group is P21/n. The structure has been solved to an R value of 0.023 for all the 1323 reflections with I > 2σ(I). The sarcosine molecule exists as zwitterion in the structure. The conformation of the sarcosine molecule is significantly changed due to the complexation of the molecule with cadmium chloride. The cadmium ion is found to have an octahedral coordination with both the oxygens of the carboxyl group of the amino acid and chlorines taking part in it. Since the complex has no water of hydration, only two hydrogen bonds of the types NH ‥ O and NH ‥ Cl are found.
Thermodiffusion and Morphological Stability in Convectionless Crystal Growth Systems from Melts and Melt‐Solutions
Authors: Rudolph P. , Boeck T. , Schmidt P.
Published: January 2007

Crystal growth experiments of multicomponent systems under microgravity require an exact analysis of the diffusion phenomena in the nutrient fluid phase. The contribution of the Soret effect to the transport and distribution of matter in a convectionless casting arrangement for shaped crystal growth and in THM melt‐solution zones have been investigated. Some semiconductor systems were analysed from experimental (Bi1‐xSbx mixed crystals) and theoretical (PbTe, InP, GaAs, CdTe compounds) point of view. The criterion for constitutional supercooling was correspondingly modified. It has been distinguished between associated (AIVBVI, AIIBVI) and dissociated (AIII–BV) melt‐solutions, containing different species of diffusion (molecules or atoms, respectively).
The Crystal Structure of Hydrated Barium Copper Oxalate
Authors: Kasthuri V. Bangera , Rao P. Mohan , Nethaji M.
Published: January 2007

BaCu(C2O42.6 H2O is triclinic, P1, with a = 6.5405(9), b = 9.202(3), c = 10.939(1) Å, α = 85.46(2), β = 79.22(1), γ = 80.45(2), V = 636.99(1) Å3, Z = 2, D0 = 2.14, Dc = 2.465 g. cm−3, R = 0.074, wR = 0.0746 for 2219 significant reflections |F0|≧ 6.0σF0. The barium has eleven coordinations and the coordination polyhedra is a capped antiprism. Six water oxygen atoms are coordinated whereas the other five are coming from the oxalate group. In the unit cell the molecules form a polymeric network. One lattice water molecule belongs to the coordinating water. The barium oxygen distances vary from 2.75 Å to 3.15 Å.
Far Infrared and Raman Optical Study of CdInGaS4, CdIn2S4, HgInGaS4 and CdIn2S2Se2 Crystals
Authors: Syrbu N. N. , Radautsan S. I. , Cretu R. V. , Tezlevan V. E. , Moldoveanu N. A.
Published: January 2007

Raman and infrared reflectivity spectra of CdInGaS4, CdIn2G4, HgInGaS4, and CdIn2S2Se2 crystals have been investigated. The fiindamental phonon parameters, the limiting dielectric constants ϵ0 and ϵ∞ and the reflectivity spectrum contours have been calculated using classical dispersion relations.
Elastic Behaviour of Some Substituted Nickel ferrites
Authors: Rao K. Vishnu Prasad , Purushotham Y. , Chandel J. S.
Published: January 2007

The longitudinal and shcar wave velocities of some substituted nickel ferrites Ni1.05Sn0.05Fe1.9‐x (Cr or Al)xO4 were determined at room temperature by the pulse transmission technique. The elastic moduli have been corrected to theoretical density. A linear relationship between Debye temperature and average sound velocity has also been observed.
High‐temperature Localization of Plastic Deformation in Lithium Fluoride Single Crystals
Authors: Skvortsova N. P.
Published: January 2007

Experimental results on the superlocalization of plastic deformation at high strains and high temperatures in LiF single crystals are described. The physical conditions of transition to a localized plastic flow in the temperature range of 603 K to 1073 K T (0.53–0.94Tmp) using constant strain rate compression tests under strain rates from 10−3s−1 to 10−2s−1 are found. The results indicate that the deformation mechanism involves dislocation climb, controlled by diffusion. The connection of high temperature flow instability with an excessive concentration of point defects (strain vacancies) in zone of shear has been confirmed.
On the Behaviour of Thermoacoustic Parameters in Liquid Crystals
Authors: Reddy R. R. , Ahamed Y. Nazeer , Kumar M. Ravi , Rao T. V. R.
Published: January 2007

Thermoacoustical parameters of liquid crystals are evaluated in terms of the coefficient of volume expansivity. The MOELWYN‐HUGHES parameter has been utilized to estimate a number of thermoacoustical parameters namely the isothermal, isobaric, and isochoric Grüneisen parameters, the repulsive exponent of intermolecular potential; the molecular constant, the fractional available volume, the Sharma constant, and Anderson‐Grüneisen parameter for a few liquid crystals at different temperatures. At the transition temperature when the mesogen transists from a highly disordered isotropically liquid state to a more ordered and dense nematic state, α exhibits a high value and this high value in α causes a sharp fall in S0 and enables to establish the transition temperatures more precisely is mesogen. It is noticed that S0 also exhibits pretransitional temperature as α does. In all these systems the S0 parameter, which is a characteristic constant imparts, on the average a constant value of 1.11 ± 0.01 both in the isotropic and nematic phases. The general behaviour of other thermoacoustical parameters have been clearly demonstrated.
Studies on the Structure of alpha‐Quinacridone
Authors: Lincke G. , Finzel H.‐U.
Published: January 2007

Alpha‐quinacridone crystallizes in the triclinic space group P1withZ= 2,a= 14.934 ± 0.064 Å,b= 3.622 ± 0.004 Å,c= 12.935 ± 0.040 Å; α = 91.39 ± 0.28°, β = 107.13 ± 0.02°, γ = 92.84 ± 0.24°. The molecules are connected by hydrogen bonds more far from linearity (≈145°) than gamma‐quinacridone 162°). Together with π‐π bonds, building molecular stacks along the short axisb= 3.622 Å, both types of bonds run through the whole lattice. Molecules within the hydrophobic planes exhibit orientational disorder. Transitions between gamma‐ and alpha‐quinacridone has been discussed: all inversion centers are retained, only the vectors of bravais lattice and the angles of molecules in the stacks are changed. The calculated pattern of alpha‐quinacridone is compared with the experimental one by means of overlay‐ and difference plots. – The transition character of the alpha‐quinacridone is stressed by generation of a combined pattern of 50% alpha‐ and 50% gamma‐quinacridone, calculating an experimental alpha‐quinacridone.
Speed Dependency of Abrasion during AFM‐Scanning under High Load
Authors: Wolf B. , Paufler P.
Published: January 2007

The paper discusses general questions of friction and wear from the point of material sensitivity in AFM studies. The depth of generated grooves after scanning under high load proved a tool of material characterization. The erosion depth was found to sensitively depend on the scanning speed. A model for quantitative discussion of this phenomenon is presented, which also explains the relation between external load and lateral friction force.
Research of the Central Core in Bi12SiO20Crystals
Authors: Gospodinov M. , Tassev V. , Dimitrov K.
Published: January 2007

The structure of the so‐called “central core” within Czochralski grown Bi12SiO20crystals is investigated by the laser projection. A finer structure with a number of optical inhomogeneities with irregular forms and sizes about 2–3 μm is observed within the core. The conditions for facet growth and absorption of impurities on the facets are described. Positron lifetime measurements are carried out within and outside the core. The results show a higher concentration of defects in regions within the core. The optical rotatory power in regions within and outside of the core was measured, too. An evaluation of the distribution of the different structural units and the dopants is made. Some suppositions about the kind and the role of the defective center are given.
Thermoanalytical and X‐ray Studies of Rapidly Solidified K2CO3
Authors: Vassilev G. P.
Published: January 2007

Molten K2CO3 was rapidly solidified, and investigatcd using DSC, X‐ray analysis and infrared spectra. All thermoanalytical investigations have been carried out in the temperature interval from 20 to 450 °C. The sorption of water by the anhydrous potassium carbonate is the reason for appearance of K2CO3 · 1.5 H2O in the specimens. The desorption processes occur in two stages usually. The enthalpics of desorption were estimated to be about 23000 J/mol. The polymorphic phase transitions of K2CO3 were studied and compared with literature data.