Features of electronic polarizability and approach to unique properties in tellurite glasses

Tellurite glasses showing unique properties such as low phonon energy and high linear and nonlinear optical properties have been considered as promising materials for photonic device applications. The present article reviews the current status of the electronic polarizability in binary and ternary tellurite glasses and approaches their unique properties. Tellurite glasses consisting of basic modifier oxides (eg, Na2O, ZnO) and basic conditional glass forming oxide (TeO2) exhibit the features of high electronic polarizability and weak chemical bond strength, that is, refractive index-based large oxide ion polarizability alpha(O2-)(n(o)), large optical basicity perpendicular to(n(o)), small interionic interaction parameter A(n(o)), and small single bond strength BM-O. The values of alpha(O2-)(n(o)), perpendicular to(n(o)), and A(n(o)) in several tellurite glasses containing WO3, Nb2O5, and Bi2O3 were estimated in this article, and a good correlation was confirmed between perpendicular to(n(o)) and A(n(o)). Unique properties of low glass transition temperature, fragile structural relaxation behavior, poor mechanical properties, high third-order nonlinear optical susceptibilities in tellurite glasses were discussed from the point of electronic polarizability.