THE INFLUENCE OF QUENCHING TEMPERATURE AND MELT COOLING RATE ON THE BINARY BARIUM FLUOROZIRCONATE GLASSES STRUCTURE

摘要

Short range order structure of the 66.7ZrF_4 - 33.3BaF_2 melt in the temperature range from 873 to 1073 K and the effect of melt cooling conditions on structure of the xZrF_4 - (1-x) BaF_2 (x=66.7, 60, 50 mol.%) glasses were studied by X-ray diffraction method. The obtained diffraction data indicated that with increasing melt temperature from 873 to 1073 K Zr(F) coordination number decreased from 7.3 to 4.0. Structural parameters of the 66.7ZrF_4 - 33.3BaF_2 glass depend on both the quenching temperature and the melt cooling rate. For the rapidly quenched ( ～ 10~5 K/s) glass samples Zr(F) coordination number and Zr-F distances decrease from 7.8 and 0.210 nm to 6.0 and 0.205 nm with increasing quenching temperature from 873 to 1273 K. On the contrary, the values of Zr-F distances and Zr(F) coordination number increase with decreasing melt cooling rate from ～ 10~~5 to ～ 50 K/s. The dependence of structural parameters on quenching temperature decreases with increasing BaF_2 content in glass.