Effect of sintering temperature on structural and electrical properties of prepared through citrate auto-ignition method

Na_0.5Bi_0.5TiO₃ (NBT) having an ABO₃ distorted perovskite structure, has received increasing attention in recent years in developing lead-free materials. NBT has been investigated intensely as solid electrolytes for Intermediate Temperature SOFCs (IT-SOFCs). In this work we have prepared NBT through citrate auto ignition method and sintered at different temperatures. The analysis of X-ray diffraction patterns confirmed the presence of rhombohedral perovskite as a primary phase with space group R3c in all the samples. Lattice parameters, particle size and lattice strain values are obtained using Rietveld Analysis of the XRD profiles. Electrical data was recorded using a LCR meter in the frequency range 42 Hz to 5 MHz and in the temperature range 100 °C to 540 °C. The data were analyzed using impedance spectroscopy analysis which indicated the presence of non-Debye type relaxation for all the samples. The electrical analysis shows the dc conductivity to be thermally activated. It increases with increase in measuring temperature while decreases with increase in sintering temperature. The nature of impedance spectra reveals the presence of both grain and grain boundary contribution. Detailed analysis of the obtained results will be reported in the presentation. (author)