Piezoelectric and Ultrasonic Studies of New Lamellar Crystals of CuInP2S6Type

Abstract The ultrasonic and piezoelectric investigations were performed in CuInP2S6 family layered crystals, where Cu, In, S were substituted by Ag, Bi and Se. We have shown that in CuBiP2Se6 crystals the anomalies of piezoelectric sensitivity and ultrasonic velocity appears in the vicinity of two phase transitions at 145 K and 220 K. In AgBiP2S6 layered crystals the only one anomaly of ultrasonic velocity and attenuation was observed at 220 K. In these crystals below room temperature the large ultrasonic attenuation and corresponding velocity dispersion were observed. Such ultrasonic behaviour was supposed to be determined by acoustoionic interaction due to large ionic conductivity of Ag+ cations. Keywords: Ferroelectricsphase transitionsultrasonic and piezoelectric properties