Insights into the dielectric and luminescent properties of Na0.5Pr0.003Bi0.497−xLaxTiO3 synthesized by the Pechini method

Abstract

Lead-free ferroelectric ceramics based on the Na_0.5Bi_0.5TiO₃ system, in solid solution with Pr³⁺ and La³⁺, are synthesized by the Pechini method at low temperature. The powders calcined at 700 °C are found to be below 200 nm in mean crystal size. The dielectric properties reveal a diffuse phase transition. In Na_0.5Bi_0.5TiO₃ ceramics the rhombohedral to tetragonal transition temperature (T_R–T) appears near 190 °C, and the Curie temperature (T_C) at 280 °C. These transitions are shifted when Pr³⁺ and La³⁺ cations are introduced into the lattice. The ferroelectric properties are also affected, causing the remnant polarization and coercive field to diminish with the increase in La³⁺ content. In addition, the piezoelectric properties decrease in the same way with La³⁺ concentration. Finally, the red luminescence of Pr³⁺ is improved when lanthanum concentration is increased.