Crystallization behavior of hafnium fluoride-based fluorochloride glasses

Abstract

The crystallization mechanism of chlorine-containing fluorohafnate glasses with the compositions (65–56)HfF₄ · (20–x)BaF₂ · xBaCl₂ · 4LaF₃ · (3–y)AlF₃ · yInF₃ · (5–18)NaF has been studied by X-ray diffraction and differential thermal analysis. The results demonstrate that characteristic features of the glasses are a decrease in glass transition temperature and the precipitation of fine-particle crystalline chloride phases at temperatures below the crystallization temperature of their fluoride analogs. We have studied the effect of the Cl/F ratio in the glass batch and the melt cooling rate on the crystallization behavior of the glasses and determined the heat treatment temperature and time for the formation of transparent glassceramic materials. The luminescence properties of Er³⁺-doped fluoride and fluorochloride glasses and glassceramics prepared from them have been investigated in the 1.5-µm range.