Maxwell–Wagner relaxation and anomalies of physical properties in Cu0.15Fe1.7PS3 mixed material

Abstract

In this contribution the broadband dielectric spectra of newly synthesized Cu0.15Fe1.7PS3 polycrystalline material are presented in a wide temperature range. The dielectric/electric properties of Cu0.15Fe1.7PS3 are governed by the Maxwell–Wagner relaxation, arising at the interfaces between crystallites and boundaries. No ferroelectric phase transition was detected by broadband dielectric investigations in the temperature range from 25 K to 300 K. However anomalies of the electrical conductivity, the thermal capacity and the ultrasonic attenuation indicate a structural transition close to 109 K. The activation energy has been calculated from the temperature dependence of the DC conductivity and compared with conductivity activation energy values of FePS3, CuCrP2S6 and CuInP2S6 crystals. The values of the dc conductivity activation energy and the dielectric relaxation are very low, indicating that the hopping between shallow energy levels is the main electrical conductivity mechanism.