Some optical and thermal properties of CsCuCl3and its phase transition near 423K

Abstract

Optical rotatory power, birefringence and thermal expansion were measured near the structural phase transition point of CsCuCl3. All these quantities show discontinuous changes at the transition point. Enantiomorphic domains were observed in the low-temperature phase and irreversible temperature dependence of the optical rotation angle is ascribed to this domain formation. Helical atomic displacements are explained in terms of the condensation of doubly degenerate E1 phonon modes at +or-q0=(0 0+or-2 pi /3c) which is induced by the cooperative Jahn-Teller effect.