Broadband dielectric investigations of indium rich CuInP2S6layered crystals

Results on dielectric properties of layered indium rich CuIn1+δP2S6 crystals are presented. At low frequencies and high temperatures, the dielectric spectra are strongly influenced by the high ionic conductivity with the activation energy corresponding to 6815 K (0.587 eV). The high-frequency part of the dielectric spectra is determined by the relaxational soft mode. The critical slowing down and Debye-type dispersion show an order–disorder type of the ferrielectric phase transition at 330 K, which is substantially higher than for pure CuInP2S6. The high ferrielectric phase transition temperature suggests an idea that a frustrated ordering should appears in indium sublattice at low temperatures. Indeed, at low temperatures the complex dielectric permittivity exhibits behaviour typical for dipolar glasses.