Grains and grain boundaries contribution to dielectric relaxations and conduction of Bi₅Ti₃FeO₁₅ ceramics

Dielectric relaxation behaviors of Aurivillius Bi₅Ti₃FeO₁₅ ceramics were investigated in a wide range of frequency and temperature via dielectric and impedance spectroscopies. We distinguished two dielectric relaxations using the combination of impedance and modulus analysis. Resistance of the grain boundary was found to be much larger than grains, whereas capacitance was at the same level. The kinetic analysis of dielectric data was carried out to evaluate the contributions of microstructure and defects to the relaxation and conduction. The possible relaxation-conduction mechanism in the ceramics was discussed. The results enable deep understanding of microstructure-defect-relaxation behaviors in Bi₅Ti₃FeO₁₅ ceramics.