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  • Author or Editor: V. Krämer x
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For the selection of appropriate crystal growth methods for multi-component compounds, a detailed knowledge of the corresponding phase diagrams is desirable. It will be shown that differential thermal analysis (DTA) combined with chemical vapour transport (CVT) represents a versatile method for evaluation of the required phase diagrams. By means of DTA, liquidus and solidus curves can be established. The application of CVT with halogens yields suitable insights into the phase relationships of the subsolidus region, because the equilibrium compositions frequently occur as single-crystalline and spatially separated phases. The advantages of combining DTA and CVT are illustrated by the recently studied binary systems Ag2S-Ga2S3, PbS-In2S3, Ga2S3 and In2S3-Bi2S3, in which numerous new ternary compounds have been found. Supplementary thermogravimetric measurements on the chalcogenide halide systems Bi2S3-BiX3 and Bi2O3-BiI3 are added.

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Abstract  

The binary system Li2Se-In2Se3 was investigated in the range of 40 to 100 mol% In2Se3 by thermoanalytical and X-ray methods. The system is characterized by two eutectic points. Beside the two binary components and the known ternary compound LiInSe2 another ternary compound crystallizes in this binary system at 83.3 mol% In2Se3. This compound was identified as LiIn5Se8. In contrast to (Cu, Ag)IB5 IIIC8 VI compounds such as CuIn5S8 [1] it does not crystallize in the spinel structure. LiIn5Se8 shows a stratified structure. The melting point was determined to be at 810C. Starting from room temperature up to the melting point no phase transitions were observed.

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Abstract  

Differential thermal analysis has been carried out on AgGaS2 samples in order to investigate the relationship between the superheating of the melt and the supercooling behaviour of the material leading to an improvement of crystal growth conditions. The knowledge gained will be correlated to the crystal growth experiments which had been carried out by using the gradient freezing method.

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Six alkali metal nitrates and nitrites were evaporated in vacuum at a constant heating rate in a combined mass spectrometric and thermogravimetric apparatus. Time resolved profiles of decomposition gases and kinetics were obtained for LiNO3, NaNO3, KNO3, Na/KNO3, NaNO2 and KNO2. Activation energies for the evaporation of these salts were calculated and compared to previous results of isothermal experiments. In the temperature range 650–850 K, the decomposing nitrates released NO, N2 and O2 while the nitrites released only NO and N2.

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