Isomorphic substitutions in the CeO2?La2O3 system at 850° C

It was proved that there are two isomorphic series of mixed crystals in the CeO₂ La₂O₃ systems from 0 to 14 mol% CeO₂-mixed crystals based on the La₂O₃ structure and from 32 to 100 mol% CeO₂-mixed crystals based on the CeO₂ structure. The oxides were obtained by co-precipitation of oxalates, followed by heating at 850 °C. The changes of the parameters of the lattice with the changes of the composition were investigated. Also the solubility of the mixed crystals in 25% HCl was determined.     

The Distribution Coefficient of Isomorphous Admixtures for KCI?KBr?H2O,K2SO4?(NH4)2SO4?H2O and KNO3?NH4 NO3?H2O Systems at 298 K

For the systems KCI KBr H₂O, K₂SO₄4-(NH₄)₂H₂O and KNO₃ NH₄NO₃ H₂ O equilibrium investigations have been performed and the distribution coefficients of isomorphous admixtures have been determined. For each solid solution the changes of the distribution coefficient D, the dependencies between the values of the real and ideal distribution coefficients and the directions of energetic changes in these systems during the co-crystallization of isomorphous and isodimorphous admixtures have been discussed.     

Epitaktische Abscheidung von GaAs im System Ga(CH3)3?AsH3?H2 (I) Autoepitaktische Abscheidung

Some aspects of Ga(CH₃)₃/AsH₃/H₂ pyrolysis are described. The quality of the epitaxial GaAs layers on GaAs substrates is examined by chemical etching, X-ray technique and observation of the surface morphology. The investigations show a relation between the quality of the layers and growth conditions (As/Ga-proportion, substrate temperature).     

Crystal Packing of Potentially Mesomorphic Azobenezene Derivatives R1–C6H4–N=N–C6H4–R2 (R1, R2 = CH3COO,C2H5O; CH2=C(CH3)COO,C2H5; C6H13COO,C2H5O)

Crystallography Reports - The structure and thermal properties of azobenzene derivatives R1–C6H4–N=N–C6H4–R2, where R1/R2 = CH3COO/C2H5O (I), CH2=C(CH3)COO/C2H5 (II), or...     

Crystal growth of Ca3−xYxMn2Ge3O12 and phase relations in the PbO?B2O3?GeO2 based melts

The bulk crystals of Ca_3−xY_xMn₂Ge₃O₁₂ garnets were grown on a seed from the PbO B₂O₃ GeO₂ based melts, where the primary crystallization field of garnets was found. The saturation temperatures of the melts were determined before each growth run. The dependence of Y incorporation into the crystals versus the melt composition was also evaluated.     

Phase relations and crystal growth of YBa2Cu3O7−δ in the system YO1.5?BaO?CuO

The liquidus face of the system YBa₂Cu₃O_7−δ BaCuO₂ CuO was investigated by DTA. We found liquidus temperatures below 1000 °C only in a narrow region with small yttrium oxide content near the eutectic of the system BaCuO₂ CuO. The crystallization path of crystal growth experiments is discussed and the principle structure of the phase diagram is derived. Single crystals are grown being superconductive after thermal treatment in oxygen atmosphere.     

Hydrothermal synthesis of (Zr0.33 Ti0.67) O2–srilankite in the system ZrO2?TiO2?H2O?MF; (M = Na,K)

The hydrothermal synthesis in the system ZrO₂ TiO₂ H₂O MF; (M = Na, K) is discussed for the temperature range 573 K–773 K and the pressure of 100 MPa to 150 MPa. Starting with Zr- and Ti- butoxides their co-precipitated hydrolysates which had been annealed in different ways were used as initial products. The formation of mixed crystals (Zr, Ti)O₂ analogous to the rare mineral srilankite was dependent on the crystallinity and homogeneity of the initial products. 573 K and 100 MPa proved to be the most favourable conditions for synthesis. Higher temperatures (773 K) produced multiphase crystallizates of (Zr, Ti)O₂, baddeleyite, anatas, and rutile.     

Epitaxial Deposition of GaAs in the Ga (CH3)3?AsH3?H2-System (IV) Thermodynamic and Kinetic Considerations

For reactions taking place between the species Ga, As₂, As₄, AsH₃, and H₂, the equilibrium constants were calculated. The discussion indicates that factors other than thermodynamic considerations significantly influence the deposition process. Kinetic investigations demonstrate the importance of the As:Ga proportion that has to apply for perfect layer growth. The mechanism of deposition is in correspondence with a Langmuir-Rideal Model. For high substrate temperatures a homogeneous reaction in the vapour phase can-not be excluded.     

Epitaxial Deposition of GaAs in the Ga(CH3)3?AsH3?H2 System (III) Heteroepitaxy on Isolating Substrates

Epitaxial growth of GaAs has been achieved on CaF₂, α-Al₂O₃ and spinel substrates. X-ray investigations showed well defined relations between layer perfection and the quality of substrate material. The formation of epitaxial layers in pyrolytic deposition processes is discussed in terms of supersaturation and its influence on nucleation and layer growth.     

Vapour Phase Epitaxy of GaxIn1−xAs in the Ga?In?HCl?AsH3?H2-System Using a Mixed Ga/In Source

The mixed crystal composition of Ga_xIn_1−xAs layers is analysed as a function of the composition of a mixed Ga/In source during VPE in the hydride system. Experimental results are compared with thermodynamic calculations. Both thermodynamics of the deposition reactions and thermodynamies of the souree reactions are considered in the calculations.     

Synthesis, Structure and Properties of (H2NCH2CH2NH3)3 {(VO)6 [B10O16 (OH)6]2} · 11H2O

Abstract A new polyoxovanadoborate cluster (H₂NCH₂CH₂NH₃)₃ {(VO)₆[B₁₀O₁₆(OH)₆]₂} · 11H₂O was prepared by hydrothermal technique and characterized by single crystal X-ray diffraction analysis, IR and TGA. The crystal of the new compound belongs to monoclinic system, space group C2/c with a = 20.198(1) ?, b = 13.4476(8) ?, c = 21.602(1) ?, β = 97.067(1)°, V = 5822.8(5) ?³, Z = 4, D _c = 1.956 g cm⁻³, M = 1714.4, μ = 1.066 mm⁻¹, S = 1.905, R = 0.059, R _w = 0.0966. Index Abstract A new polyoxovanadoborate cluster (H2NCH2CH2NH3)3{(VO)6 [B10O16(OH)6]2} · 11H2O was prepared by hydrothermal technique and characterized by single crystal X-ray diffraction analysis, IR and TGA.      

Epitaxial Deposition of GaAs in the Ga(CH3)3?AsH3?H2 system (II). Investigations on the Hetero-Epitaxy of GaAs on Ge

Epitaxial GaAs layers have been deposited on (111), (110) and (100) faces of Ge by pyrolysis of Ga(CH₃)₃ AsH₃ H₂. In this paper the influence of growth conditions and the lattice difference of GaAs and Ge on the quality of epitaxial GaAs layers is described and discussed. The epitaxial layers are characterized by chemical etching, X-ray investigations, and by the observation of the surface morphology.     

X-ray powder diffraction investigations of solid solutions with limited miscibility in the KNO3?NH4NO3?H2O system at 298 K

The measurements of crystal lattice parameters (a, b, c) were conducted and the volumes (v) of unit cells of solid solutions forming in the system KNO₃ NH₄NO₃ H₂O at 298 K were calculated. It was established that in this system at 298 K two series of solid solutions were formed: the mNH₄NO₃ · n(KNO₃ · 2 NH₄NO₃) solid solution with the gap of miscibility and the kKNO₃ · l(KNO₃ · 2 NH₄NO₃) solid solution with one-sided limited miscibility.     

Mesophase-Preceding Crystal Packing of 4,4'-Dialkyl-Substituted Salicylideneanilines; C10H21O–C6H3(OH)–CH=N–C6H4–С7Н13) Structure

Crystallography Reports - The crystal structure of 4,4'-substituted salicylideneaniline C10H21O–C6H3(OH)–CH=N–C6H4–C7H13 has been investigated by X-ray diffraction. A...     

Growth of crystals of ferroelectrics Ln2Ti2O7 (LnLa?Nd) with layer-type structure

Single crystals of rare-earth (La-Nd, Sm, Gd) and Y dititanates have been grown either by the method of direct high frequency heating in cold container or/and floating zone optical technique. The crystals Ce₂Ti₂O₇ and Pr₂Ti₂O₇ belong to the structural type of Ca₂Nb₂O₇ and possess dielectric and optic characteristics which are very similar to that of known ferroelectrics La₂Ti₂O₇ and Nd₂Ti₂O₇.     

一个新的过氧钼酸盐(NH4)4(CH6N3)2[Mo7O23(O2)]·3H2O的合成、晶体结构及催化性质

以钼酸铵和盐酸胍为原料,30;双氧水为氧化剂,在室温下采用常规的水溶液法合成了一种新的单过氧七核钼酸盐(NH4)4(CH6 N3)2[Mo7O23(O2)]·3H2O,通过元素分析、X-射线单晶衍射、红外光谱、固体紫外可见光谱对其进行了表征.标题化合物属于单斜晶系,P21/n空间群,a=1.367(14) nm,b=1.085(11) nm,c =2.748(3) nm,β=93.15(2)°,V=4.0685(7) nm3,Z=4,Dc=2.031g· cm-3,R1 =0.0713,wR2 =0.2199(I＞2σ),GOF=1.03.将合成的过氧钼酸盐(NH4)4(CH6N3)2[Mo7 O23 (O2)]·3H2O作为催化剂用于苯甲醇氧化合成苯甲酸的反应,考察了催化剂用量、氧化剂(30;H2O2)的用量、反应温度、反应时间等对苯甲酸产率的影响.最佳催化反应条件是:n(催化剂)∶n(苯甲醇)=0.063∶1,n(H2O2)∶n(苯甲醇)=40∶1,反应温度85℃,反应时间7h,苯甲酸的产率达到82.2;.