Properties and crystallization behaviors of TeO 2LiNbO 3 glasses

Abstract

(100− x)TeO 2− xLiNbO 3 ( 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 LiNbO 3 content from 5.50 g/cm 3 to 4.58 g/cm 3. 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 TeO 4 trigonal bipyramid, TeO 3 trigonal pyramid and NbO 6 octahedra. In the glasses with x = 10 and 20, α-TeO 2 (paratellurite) crystals were precipitated by heat treatment above 450°C. In the glasses with x ≧ 40, LiNbO 3 crystals were formed through the transformation of a metastable pyrochlore-type compound at temperatures above 500°C. From the present study, it is proposed that the fabrication of transparent TeO 2-based glasses containing ferroelectric LiNbO 3 microcrystallites may be possible.