Description of AC conductivity via Meyer-Neldel rule: A comparative study between oxide and chalcogenide systems

Abstract

Nature of conductivity spectra in oxide and chalcogenide systems are found to be different, which should be indication of different conduction mechanisms via polaron hopping. This behaviour has been well explored using Meyer–Neldel rule (MNR), which provides microscopic information regarding conduction nature in different systems. Optical phonon assisted polaron hopping should impart this multiexcitation process of MNR. Microstructural information of present systems is also found to be helpful to validate conductivity data. A schematic model (nanocluster model) has been proposed to describe conduction mechanism in these complicated disordered solids. TEM micrographs and selected area electron diffraction (SAED) patterns reveal the agglomerates (cluster) in the oxide system, which may be favourable for stability of the system. More dislocations in the chalcogenide system should make the system unstable. This feature of instability should make them suitable candidates for more doping, which should increase their semiconducting nature.