Elucidating the conduction behavior in KBT ceramic

Abstract

Single-phase powder of lead-free ferroelectric potassium bismuth titanate (K0.5Bi0.5TiO3, abbreviated as KBT) was prepared by the modified sol-gel process, and the crystal structure, microstructure, and electrical properties were investigated. Powder x-ray diffraction pattern confirmed that KBT crystallized in tetragonal (space group: P4mm) unit cell at room temperature. A frequency-dependent diffuse dielectric anomaly ~ 356 °C (at 1 MHz) was observed in dielectric constant versus temperature curve. Impedance spectroscopy was employed to study the effect of temperature on conduction and relaxation mechanisms. Temperature dependence of DC conductivity and the relaxation frequency were found to obey Arrhenius behavior, and the activation energies calculated from the linear fitting were found to be 1.02 ± 0.01 eV and 1.08 ± 0.01 eV, respectively. The conduction in 355 °C-505 °C temperature range was attributed to the movement of oxygen vacancies. © 2020 American Institute of Physics Inc.. All rights reserved.