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  • Author or Editor: D. Klissurski x
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Abstract  

The thermal decomposition of copper sulphate hydroxide hydrate, (CuO·CuSO4). 2Cu(OH)2·H2O, to copper oxysulphate and CuO was investigated by X-ray phase analysis, IR spectroscopy, complex thermal analysis and electron microscopy. The effect of water vapour and time of treatment on the formation of decomposition products with a large surface area is studied. The strong decrease in specific surface area of the precipitate (from 80 m2/g to 20 m2/g) thermally treated at a temperature above 250°C is associated with the elimination of water having a coordination bond with the Cu2+ ion. During this process, the interplanar distances of the crystal lattice of copper sulphate hydroxide hydrate decrease. The time of decomposition of this compound essentially affects the decrease of the specific surface area. When the decomposition proceeds in an atmosphere containing water vapour sintering processes are predominating and the phase obtained has a considerably smaller specific surface area than in cases of decomposition under dry air.

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Abstract  

Characteristic temperatures, such as T g (glass transition), T x (crystallization temperature) and T l (liquidus temperature) of glasses from the V2O5-MoO3-Bi2O3 system were determined by means of differential thermal analysis (DTA). The higher content of MoO3 improved the thermal stability of the glasses as well as the glass forming ability. The non-isothermal crystallization was investigated and following energies of the crystal growth were obtained: glass #1 (80V2O520Bi2O3) E G=280 kJ mol-1, glass #2 (40V2O530MoO330Bi2O3) E G=422 kJ mol-1 and glass #3 (80MoO310V2O510Bi2O3) E G=305 kJ mol-1. The crystallization mechanism of glass #1 (n=3) is bulk, of glass #3 (n=1) is surface. Bulk and surface crystallization was supposed in glass #2. The presence of high content of a vanadium oxide acts as a nucleation agent and facilitates bulk crystallization.

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