Ceramics-Silikáty 51 (2) 112-118 (2007)

THE CRYSTALLISATION OF CALCIUM PHOSPHATE GLASS CONTAINING VANADIUM OXIDE

V. D. Živanovic, M. B. Tošić, N. S. Blagojević, S. R. Grujić, M. M. Mitrović

The crystallisation behaviour of calcium phosphate glass containing vanadium oxide was studied. Glass with a molar ratio of [CaO]/[P₂O₅] = 1.13 and a V₂O₅ content of 8 mol.% was prepared for the experiments. The crystallisation of bulk glass samples was performed under isothermal conditions at T = 650-820°C. The surface crystallisation mechanism of studied glass with dendritic growth of the primary -Ca₂P₂O₇ phase was observed. In all crystallised samples, -Ca₂P₂O₇ and VP₂O₇ appeared as the secondary phases. In the investigated temperature range, crystal growth rates 9  10^-9 - 2.14  10^-6 m/s were determined. The temperature dependence of the crystal growth rate makes possible to calculate activation energy E_a = 407 ± 30 kJ/mol of crystallization. The experimental data were compared with those estimated by using a theoretical model of the crystal growth rate and good agreement between the results was found.

Keywords: Phosphate glass, Vanadium oxide, Crystallisation.