Microstructural and high temperature dielectric, ferroelectric and complex impedance spectroscopic properties of BiFeO3 modified NBT-BT lead free ferroelectric ceramics

Highlights: • Modified solgel process is used to synthesize nano structured NBT-BT-BF compositions. • The effect of Ba ion substitution at A-site and Fe ion substitution at B site in NBT ceramics is reported. • The conductivity increases with temperature above 150 °C confirming the NTCR behavior. • The dielectric peak temperature increased with the increase of BF concentration. - Abstract: Solid solutions of nano structured Na_0.5Bi_0.5TiO₃-Ba_0.925Nd_0.05TiO₃-BiFeO₃ (0.7NBT-0.2BT1-0.1BF & 0.7NBT-0.1BT1-0.2BF) compositions were prepared by the conventional sol-gel method and the effect of BiFeO₃ addition on microstructure, dielectric, ferroelectric and high temperature electrical properties of NBT-BT1-BF ceramics were investigated through XRD, SEM, dielectric and electrical characterization. X-ray diffraction patterns are well indexed and found that samples are crystallized in rhombohedral phase. SEM images have shown uniform distribution of grains and change in grain size with BiFeO₃ concentration. The samples exhibited relaxor behavior, which is accompanied by a shift in ε_max and Z'' towards high temperature with increasing BiFeO₃ concentration. The grain and grain boundary response as well as the relaxation processes at different frequencies and temperatures were discussed. These observations suggest that BiFeO₃ addition to NBT-BT1 ceramics can be considered as a potential lead free ceramic system in multi-ferroic devices.