PROPERTIES AND CRYSTALLIZATION BEHAVIORS OF TEO2-LINBO3 GLASSES

(100 - x)TeO2 - xLiNbO3 (x = 10-60) glasses were prepared by using a conventional melt-quenching method, and some properties such as thermal stability, density and refractive index and crystallization behaviors of glasses were measured. The thermal stability of the glasses with x = 20 and 30 was high. The density of glasses decreased monotonically with increasing LiNbO3 content from 5.50 g/cm3 to 4.58 g/cm3. The values of the refractive index of glasses were 2.04-2.11 and showed an anomalous compositional dependence. It was found from Raman scattering spectra that the structure of glasses was composed of the structural units of TeO4 trigonal bipyramid, TeO3 trigonal pyramid and NbO6 octahedra. In the glasses with x = 10 and 20, alpha-TeO2 (paratellurite) crystals were precipitated by heat treatment above 450-degrees-C. In the glasses with x greater-than-or-equal-to 40, LiNbO3 crystals were formed through the transformation of a metastable pyrochlore-type compound at temperatures above 500-degrees-C. From the present study, it is proposed that the fabrication of transparent TeO2-based glasses containing ferroelectric LiNbO3 microcrystallites may be possible.