Optical birefringence imaging of the phase transition of K2Mn2(SO4)3

Abstract

The present paper reports on the observation of the optical birefringence as a function of temperature of the langbeinite-type crystal K2Mn2(SO4)3by using an imaging version of the so-called rotating-polarizer method. This method provides separate moving images of the orientation of the optical indicatrix and the magnitude of the optical anisotropy, showing the domain-wall behaviour during temperature changes. Some new results on the domain behaviour of the phase transition of K2Mn2(SO4)3have been obtained. It is concluded that the sample single crystal consists of local regions, indicating the coexistence of two phases in this langbeinite-type crystal.