Electronic polarizability and its temperature dependence of Bi 2O 3–B 2O 3 glasses

Abstract

The refractive index ( n) and density ( ρ) of xBi 2O 3–(100 − x)B 2O 3 glasses with x = 32.5–60 (mol%) are measured in the temperature range of 30–150 °C in order to clarify the temperature dependence of the electronic polarizability of oxide ions ( α O2− ) and optical basicity ( Λ). It is found that the values of n, α O2− , and Λ increase almost linearly with increasing temperature. The value of the temperature dependence of refractive index, d n/d T, increases with increasing Bi 2O 3 content. Contrary, the values of d α O2 − /d T, and d Λ/d T, tend to decrease with increasing Bi 2O 3 content. It is suggested that the temperature dependence of the electronic polarizability of oxide ions in xBi 2O 3–(100 − x)B 2O 3 glasses has a large contribution for the temperature dependence of the refractive index in comparison with the contribution of the volume thermal expansion coefficient. The features in the temperature dependence of α O2− and Λ in the present glass system might be related to the extremely weak single bond strength of Bi 2O 3 compared with the strong single bond strength of B 2O 3.