Optical properties and weakening of elastic moduli with increasing glass transition temperature (T g) in (80–x)TeO2-xBaO-20ZnO glasses

Abstract

Abstract BaO addition to ternary (80–x)TeO2-20ZnO-xBaO (x = 0–20 mol.%) glasses resulted in a decrease in ultrasonic velocities and independent elastic moduli; this result indicated that the rigidity of the glass network weakened possibly because non-bridging oxygen increased. Thermal analysis results showed that glass transition temperature increased as BaO content increased because of the stabilizing effect of Ba2+ on the glass network. Additional analyses using bulk compression and ring deformation models revealed that the ratio between theoretical bulk modulus and experimental bulk modulus increased; this result indicated that the compression mechanism mainly involved isotropic ring compression. Furthermore, the increase in non-bridging oxygen formation with BaO addition caused a decrease in optical energy gap and an increase in refractive index. An increase in Urbach energy indicated that the degree of disorder in the glass system also increased.