Dielectric relaxation and electrical properties of Sm_0.5Bi_4.5Ti₃FeO₁₅ ceramics

Single-phase Aurivillius Sm_0.5Bi_4.5Ti₃FeO₁₅ ceramics was synthesized by the conventional solid-state reaction technique. Dielectric response and electrical properties of the ceramics were investigated in a wide range of temperature and frequency by dielectric and impedance spectroscopies. Two dielectric relaxation behaviors were distinguished by the combination of impedance and electric modulus analysis which could be attributed to the contributions of grains and grain boundaries, respectively. The resistance of grain boundaries was found to be much larger than that of grains, whereas the capacitances were in the same level. A ferroelectric phase transition was observed to take place at ∼440 °C. The kinetic analysis was performed to study the corresponding relaxation-conduction mechanisms in the material. Above 270 °C the conduction behavior of the compound was ascribed to the motion of ionized oxygen vacancies.