Effect of Ca, Nd, and Mn substitution on the microstructural, optical, and dielectric properties of lead-free Na0.5Bi0.5TiO3 ceramics

Recently, the perovskite Na0.5Bi0.5TiO3 (NBT) and its derivatives have garnered increasing attention due to their promising multifunctional properties. This study explores the structure, microstructure, and optical, dielectric, and electrical properties of the new perovskites Na0.5Bi0.47Ca0.03TiO3 (NBCT), Na0.5Bi0.47Nd0.03TiO3 (NBNT), and Na0.5Bi0.47Mn0.03TiO3 (NBMT). X-ray diffraction analysis confirms the presence of a rhombohedral phase (R3c) in all compositions at room temperature. The introduction of modifying ions results in a significant reduction in grain size, thereby influencing the microstructure. The compounds exhibit bandgap energies ranging from 2.98 eV to 3.15 eV, characteristic of semiconducting behavior. Regarding dielectric properties, the three compounds demonstrate low leakage currents and low dielectric losses at room temperature. With increasing temperature, the NBCT compound stands out with a low loss tangent (tan (delta) approximate to 10-3) in the temperature range of 98 degrees C-258 degrees C. These findings show that the chemical modifications effectively reduce dielectric losses, particularly those related to bismuth volatilization, while enhancing the overall performance of NBT.