Dielectric and ultrasonic studies of new Ag0.1Cu0.9InP2S6 layered ferroelectric compound

Abstract

The dielectric properties of newly synthesized Ag_0.1Cu_0.9InP₂S₆ crystals were investigated in broad frequency (20 Hz – 1 MHz) and temperature range (110 K – 350 K). Anomaly in the temperature dependence of a complex dielectric permittivity indicating the polar phase transition was detected at the temperature 283 K . The dielectric properties of the presented crystal are mainly caused by conductivity and phase transition. The frequency spectra of the conductivity obey the Almond-West power law. The activation energy of the conductivity was found to be E_A/k= 6381 K. A suggestion is given that the electric conductivity in these crystals can be interpreted by ionic mechanism. The piezoelectric sensitivity was observed only when DC bias electric field was applied along direction normal to layers. In this case the piezoelectric sensitivity appeared due to electrostriction.