Dielectric constant and phase transition sequence in betaine calcium chloride dihydrate

Abstract

BCCD exhibits a sequence of structural phase transitions from a high-symmetry orthorhombic phase to different commensurate or incommensurate phases modulated along [001]. This work reports a study of the dielectric constant at a constant frequency of 10 kHz as a function of temperature. The results are discussed within the scope of Landau theory and reveal the existence of new intermediate high-order commensurate phases, in agreement with recent pyroelectric measurements.