Crossover between small polaron hopping and Mott's variable range hopping in Pr2MgTiO6

Abstract

A combined study of X-ray diffraction (XRD) pattern and Raman spectrum authenticates the lower symmetric orthorhombic Pnma structure for solid-state synthesized Pr2MgTiO6 (PMT). The Ag mode demonstrates itself as a breathing vibration of the TiO6 octahedra. The ac conductivity, dielectric relaxation, and impedance spectra highlight the joint contributions of the grain-boundaries and grain microstructures to the charge carrier dynamics in PMT. The double power-law formalism is accepted to fit ac conductivity spectra. The relaxation spectra has a non-ideal nature with the circulation of relaxation time as observed from the impedance spectroscopic data. An equivalent circuit model has been employed for fitting impedance data using a constant phase element (CPE) model. The dc conductivity investigation points towards a crossover from small polaron hopping to Mott s variable range hopping due to lowering activation energy. The crossover between two different conduction mechanisms (Mott s variable range and small polaron hopping) is investigated using a conjunction of thermal varying conductivity, dielectric relaxation and impedance spectrum in polycrystalline PMT.Comment: 10 pages, 5 figures, 4 tables. arXiv admin note: substantial text overlap with arXiv:1707.02830, text overlap with arXiv:1904.1196