Betaine compounds–a new family with ferroelectric and incommensurate phases

Abstract

Several addition compounds of the amino acid betaine and inorganic acids were found in the last years to possess structural, ferroelastic, ferroelectric or antiferroelectric phase transitions. As well commensurate as incommensurate phases are observed. The materials are betaine phosphate (antiferroelectric), betaine arsenate (ferroelectric, but antiferroelectric if deuterated), betaine borate (ferroelastic), betaine phosphite (ferroelectric), and betaine calcium chloride dihydrate (several commensurate and incommensurate phases with soft mode behavior, ferroelectric in its lowest phase).