Effect of sintering time on electrical, ferroelectric, and piezoelectric performances of microwave synthesized sodium bismuth titanate ceramics

Herein, we report the synthesis of sodium bismuth titanate (Na0.5Bi0.5TiO3/NBT), a lead-free ceramic prepared via a cost and time-effective microwave synthesis route. This work presents the investigation of microstructural, electrical, and optical characteristics of NBT ceramics. The formation of a single-phase NBT sample sintered for 30 and 40 min (denoted as NBT 30 and NBT 40) is confirmed by Rietveld refinement and Raman measurement. FTIR spectroscopy is used to characterize the single-phase nature and to confirm the presence of desired vibrational spectra in the perovskite structure. Tightly packed micron-sized grains are observed from the field emission scanning electron microscopy. Due to the A-site disorder present in the lattice, two diffuse types of dielectric anomalies are present in the temperature-dependent dielectric plot for both samples. The maximum dielectric constant values of 1475 and 1628 are found for NBT 30 and NBT 40 samples at the transition temperature. From temperature-dependent AC conductivity measurement, NBT 40 samples show a higher value of conductivity in comparison to NBT 30. The PE hysteresis loops confirm the ferroelectric character present in both samples. An improved piezoelectric coefficient is observed with increasing sintering time and is found to be 80 pCN-1 for NBT 40. The optical bandgap of materials is 3.03 and 3.1 eV for NBT 30 and NBT 40, respectively.