Deep insights into morphological, structural and dielectric properties of BaTi0.5 (Cr0.33Mo0.17) O3 ceramics

Abstract

In our present paper, the morphological, structural and electrical properties of chromium-doped BaTiO3 ceramics were investigated. BaTi0.5 (Cr0.33 Mo0.17)O3 was prepared by the sol-gel technique. Tetragonal phase with P4mm space group was observed by X-ray diffraction analysis. An excellent agreement between the calculated and the observed model was verified by Rietveld refinement. A polycrystalline compound with a particle size of 1.96 μm was identified using scanning electron microscopy. The electrical conductivity graph is divided into two regions in the frequency interval 102–106 Hz over the temperature range 480–640 K. The Ac conductivity spectrum follows the Jonscher's law. The conductivity mechanism in the studied temperature range can be explained by the Non-overlapping Small Polaron Tunnel (NSPT) model. The imaginary parts of impedance show that the maximum value of Z″ decrease with temperature rise, reflecting the progressive loss of insulating properties. In addition, the peaks of Z″ shifted to higher frequencies, indicating relaxation behaviour. Furthermore, the real part of Z″ decreased with temperature and frequency increase, indicating Negative Temperature Coefficient Resistance (NTCR) behaviour. The complex impedance plot showed large semicircular arcs corresponding to the merging of two semicircles due to grain and grain boundary contribution. Examination of the impedance and modulus normalization curves revealed a shift in both peaks, indicating the existence of a short moving carrier. The exponent “n" increased with temperature increase, which proves the existence of the Non-overlapping Small Polaron Tunnel (NSPT) model in the studied temperature range.