Investigation of optical and electrical conduction mechanism of AgYP2O7 prepared by solid state process

Abstract

Diphosphate materials are promising materials for different applications where their properties need to be widely studied in order to optimize them. The AgYP2O7 compound was prepared following the solid-state reaction method. X-ray powder reveals that the title compound crystallizes in the triclinic system, while differential scanning calorimetry analysis discloses the existence of an endothermic peak around T = 480±10 K indicating the existence of a phase transition. As for optical properties, using reflectance spectroscopy and Kubelka– Munk's procedure, the deduced value of the direct energy gap of Eg =2.29±0.09 eV. The variation in conductivity with temperature confirms the presence of the phase transition evidenced by DSC measurements. The AC conductivity data are well described by Jonsher's law. The thermal behavior of the exponent parameter "s" reveals that the conduction mechanism changes from over large polaron tunneling to non-overlapping small polaron tunneling at the temperature of phase transition.