Exploring Electronic Transport Properties of Vanadium-Doped Barium Calcium Titanate Ceramics

Abstract

This paper explores the effect of vanadium doping on electric modulus, impedance, and AC conductivity over a frequency range of 100 Hz to 1 MHz and a temperature span of 573 to 753 K in barium calcium titanate (BCT) ceramics synthesized via solid-state reaction process. The frequency-dependent AC conductivity obeys Almond–West law. Various parameters such as σ_dc, ω_H, and s have been obtained from the theoretical fitting of σ'(ω) according to Almond–West law. An analysis of the frequency exponent s indicates that the conduction mechanism in the investigated samples follows Correlated Barrier Hopping Model. The activation energy values for DC conduction range from 0.71 to 0.80 eV. The relaxation time and activation energies of the studied ceramics extracted from fitting the imaginary part of the modulus were found to be between 2.98 and 664 µs and 0.917 to 1.024 eV, respectively. Nyquist plots fitted well using a series combination of two R-CPE equivalent circuits, indicating that the relaxation process is of a non-Debye type, influenced by both grain and grain boundaries. The resistances of the grains and grain boundaries found to decrease with increasing temperature, indicating that the ceramic samples exhibit semiconducting properties. These studies suggest the applications of prepared ceramic compositions for high sensitivity sensors, capacitors used in automotive, and power electronics operating under high thermal stress, actuators, solid oxide fuel cells (SOFCs).