Optical and Dielectric Properties of K₂Mn₂(SO₄)₃

Abstract

Dielectric and birefringence measurements have been made on K 2 Mn 2 (SO 4 ) 3 crystal. Anomalous temperature dependence of the spontaneous birefringences is found in D 4 2 phase (below –80°C). The differences of photoelastic coefficients p 11 - p 12 and p 11 - p 13 are determined by the static method to be both about 0.02 at room temperature. Temperature dependence of the spontaneous birefringence and dielectric susceptibility is analyzed on the basis of thermodynamic potential proposed by Dvořák.