Effect of glycine substitution on the ferroelectric phase of betaine arsenate [(CH3)3NCH2COO·H3AsO4]

Abstract: The present work reports an experimental investigation on the influence of glycine (NH2CH2COOH) substitution in the polar properties and the critical dynamics of the molecular ferroelectric betaine arsenate, (CH3)3NCH2COO·H3AsO4. The dielectric dispersion (20Hz<ν<3MHz) and the thermally induced displacement currents are investigated in detail over the extended Curie region of the system (130K<T<100K). The results obtained for a single crystal with nominal glycine content of 20% are analyzed, compared with those obtained for pure betaine arsenate and discussed within the scope of a phenomenological Landau model previously used to describe a system with competing ferroelectric and structural instabilities. [Copyright &y& Elsevier]