Structural and thermoelectric properties of Ba0.97Nd0.0267Ti 0.95W0.05O3 ceramic

Polycrystalline sample of Ba0.97Nd0.0267Ti0.95W0.05O3 was prepared by the Molten Salt method. X-Ray diffraction (XRD) analysis using Rietveld refinement has shown that the sample under investigation crystallises in the tetragonal structure with a P4mm space group. Complex impedance analysis confirmed a non-Debye relaxation phenomenon in the compound. Moreover, this study showed a semicircle arcs modeled by an equivalent electrical circuit and explained by the contribution of the grain and grain boundaries in the transport properties. Scale behaviors implied that the distribution of relaxation times was temperature-independent, while dynamic processes for jump carriers were temperature-dependent. From the temperature dependence of the average normalized change (ANC), we deduced the temperature at which the available density of trapped charge states vanishes. AC conductivity obeys Jonscher's law and Almond-West's modified Jonscher law. The extracted value of the exponent 'n' suggests that the conduction mechanism follows the theoretical model of Overlapping Large-Polaron Tunneling (OLPT). This conduction mechanism governs the charge transport in the compound. Relaxations were associated with conductivity resulting from jump movements of singly and doubly ionized oxygen vacancies for the lower and higher temperature, respectively.