Optical investigations of thallium selenate in the temperature range between 293 K and 40 K

Abstract

The phase transition of thallium selenate (Tl2SeO4) at 72 K has been investigated by optical measurements. An optical cryostat in connection with a polarizing microscope was used to measure the temperature dependence of the optical birefringence nγ-nβ between 293 K and 72 K. The phase transition at 72 K is marked by a large change of the birefringence, along with a change of the optical sign. Moreover, below 72 K domains have been observed which are intergrown with each other parallel to (010).