Structural and physical properties of a novel TeO 2–BaO–SrO–Ta 2O 5 glass system for photonic device applications

Abstract

A detailed study on a novel TeO 2–BaO–SrO–Ta 2O 5 glass system developed for photonic device applications is reported in this paper. The glass transition and crystallization temperatures could be selected by varying the Ta 2O 5 content in this glass system. This glass system is found to have good thermal stability among tellurite glasses. Raman spectroscopy has been used as a tool to analyze the structural details of this technologically important glass system. In addition to the TeO 4 trigonal bipyramid and TeO 3 trigonal pyramid structural units, glasses in this system revealed the presence of an additional Raman band attributed to TaO 6 octahedra. The Raman bandwidth of the present glasses are broader compared to the conventional tellurite glasses by 35%. The influence of a gradual addition of the modifier oxides on the coordination geometry of tellurium atoms has been elucidated. Unlike the other tellurite glasses, even at higher modifier concentrations the TeO 4 structural units dominate in the glass network compared to TeO 3 trigonal pyramids. The ratio of TeO 4/TeO 3 structural units was discussed for different series of glass compositions.