Influence of crystallisation conditions on the microtexture of the directionally solidified eutectic of the MgF2?CaF2 system

The influence of high-frequency (HF) and resistive (R) heating of a vertical crystallizer furnace on the directional solidification process of the MgF₂ CaF₂ system eutectic has been compared. The turbulent flow induced by HF heating given rise to inhomogeneities in microtexture, which do not occur under R heating conditions. Variations in the growth rate (v) and temperature gradient (ΔT) lead to characteristic changes of the eutectic microstructure: from lamellar to rod-like. Quantitative analysis of these changes was advantageously performed using a digital image analysis of the area (AR), maximum cross-section (D-MAX), direction of the maximum cross-section (ANGLE D-MAX) of MgF₂ particles of the microtexture. This was recorded on SCAN images of transverse cuts through the given directionally solified samples as well as the analysis of the shape of MgF₂ particles.     

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.     

The influence of preageing and the cooling rate on the decomposition processes taking place during artificial ageing in Al?Zn/4.5at.%/?Mg/X/alloys

The influence of pre-ageing procedures and cooling rates on the processes taking place in Al Zn/4.5 at%/ Mg/1; 2; 3 at.% alloys during artificial ageing are studied by means of X-ray small angle scattering and transmission electronmicroscopic investigations. The main results are: The stability of the precipitates grown during the pre-ageing is increased by the increase of their size. The cooling rate is strongly influencing the decomposition processes at different ageing temperatures, T_a. Preageing procedures seem to affect the ageing behaviour at T_a remarkably only in the case when the pre-ageing temperature is far enough from T_a.     

On the influence of various pre-ageing treatments on the structure changes taking place at elevated temperatures in alloys of the type Al?Zn5?Mg1

Investigated were two alloys of Type Al-5 wt% Zn-1 wt% Mg, one of them contained additionally 0.2 wt% of Mn, Cr, Fe as well as Si (technical alloy), be means of hardness and TEM investigations.     

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.     

On the growth kinetics of Y3Fe5O12: Bi films grown from Bi2O3?PbO?B2O3 melts

LPE isothermal growth of thin films of Y_3−xBi_xFe₅O₁₂ from PbO B₂O₃ Bi₂O₃ melts was used as a tool for studies of structure of high temperature solutions (HTS). Using an anionic model of HTS enthalpy and entropy of dissolving of the garnet phase, the equilibrium constant of Bi₂O₃ dissociation and diffusion coefficients of the growth unit were calculated from experimental data.     

Spectroscopic Investigation on the Formation of a Dinuclear Me2SO–Ru2-Mercaptopyridine Bridged Complex: [Ru2Cl3(μ-pyS)(μ-dmso)(dmso)4]?·?2H2O

Abstract  A dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine (2-pyridinethiol or 2-pyridyl mercaptan) and a methyl sulfoxide (dmso) have been characterized by X-ray crystallography. The reported compound with formula [Ru₂Cl₃(μ-pyS)(μ-dmso)(dmso)₄] · 2H₂O, [C₁₅H₃₆Cl₃NO₇S₆Ru₂] (P2/c, a = 13.8175(2) ?, b = 10.5608(2) ?, c = 21.3544(3) ?, β = 106.090(1)°, V = 2,994.05(8) ?³, Z = 4) represents a seven-membered ring system with both rutheniums in an octahedral geometry. All the hydrogen bonds (C–H–Cl) and the van der Waals contacts give rise to three-dimensional network in the structure and add stability to the dinuclear compound. To our knowledge, this is the first time that the formation of a dinuclear ruthenium(II) complex double-bridged by an N-aromatic ligand 2-mercaptopyridine and dmso have been reported. The study also provided valuable insight into bioinorganic chemistry as continuing efforts are being made to develop metal-based cancer chemotherapeutics. A major feature of this paper is the resolution of a double bridged ruthenium structure which contributes to a better understanding of ruthenium reactivity. Index Abstract  A major feature of this paper is the resolution of a double bridged ruthenium structure which contributes to a better understanding of ruthenium reactivity.