Effect of samarium substitution on the dielectric and ferroelectric properties of BaBi4−xSmxTi4O15 ceramics

Abstract

Sm-substituted barium bismuth titanate BaBi4−xSmxTi4O15 (BBSTx, x=0, 0.4, 0.6, 0.8) ceramics were prepared by a solid-state reaction method. X-ray diffraction patterns showed that the ceramics have a tetragonal structure with space group of I4/mmm at room temperature. The plate-like morphology was observed by scanning electron microscope (SEM) and the average grain size decreases with the increase of Sm substitution. The dielectric, ferroelectric properties and complex impedance spectra of BaBi4−xSmxTi4O15 ceramics were studied. The results showed that Sm substitution decreased the temperature of the dielectric maximum (Tm) obviously from 390°C to 241°C. A modified Curie–Weiss law was used to describe the relaxor behavior of the ceramics. Through Arrhenius fitting, the activation energy was estimated to be 0.97–1.18eV, which could be attributed to the thermal motion of oxygen vacancies. The remnant polarization (Pr) first increases, then decreases with increasing Sm substitution, and the maximum Pr was found to be 0.60μC/cm2 for BBST0.6 ceramics.