Investigation of Compositional Effect on Dielectric and Variable Range Hopping Mechanism of Dysprosium Doped BNT-BT Ceramics

Abstract

The manuscript describes the dielectric properties and conduction mechanism of Dysprosium doped 0.92Na0.5Bi0.5TiO3–0.08BaTiO3 (BNT-BT8) composition prepared by solid-state reaction method. Rietveld refinement study of X-ray diffraction data shows that all the samples exhibit a combination of rhombohedral (R3c) and tetragonal (P4mm) crystallographic phases. It is found that with an increase in Dy content, the pseudo-cubic lattice parameter of R3c phase gradually decreases. The modification in the microstructure of the doped samples was investigated by scanning electron microscope. The temperature and frequency-dependent dielectric data show enhancement of the dielectric dispersion in the region of the dielectric peak with doping. To achieve more insight into the evolution of disorder in the system, the Landau-Devonshire (LD) cluster theory was employed to evaluate the local order parameter. The change of ac-conductivity with the temperature of the studied samples was analyzed using Arrhenius’s law and Mott’s variable range hopping mechanism. The fitting of the model parameters such as density of states (N(EF)), hopping length (RH), and hopping energies (WH) were calculated for all the compositions. The activation energy associated with the samples was calculated from the Arrhenius diagram, which reflects the conduction process is different at different temperature ranges.