Influence of isovalent and aliovalent substitutions at Ti site on bismuth sodium titanate-based compositions on piezoelectric properties

The effect of isovalent and aliovalent substitutions in Bi_0.5Na_0.485La_0.005TiO₃ (BNLT) compounds were studied within the additive ranges of 0–2.5 at%. The Zr⁴⁺, Nb⁵⁺ and Fe³⁺ ions were selected as the substituents. The modified BNLT compounds were prepared by conventionally mixed-oxide method. The calcination and sintering were performed at the temperatures of 750–850 °C and 1050–1150 °C, respectively. An increase in the substituents contents affected the physical and piezoelectric properties. The BNLT compositions with the addition of 1 at% Zr⁴⁺, Nb⁵⁺ and Fe³⁺ ions exhibited high relative permittivities (_r) at 730, 735 and 660, respectively. The modified-BNLT with an addition of 1.0 at% Fe provided a piezoelectric coefficient (d₃₃) of 155 pC/N, Curie temperature (T_c) of 320 °C and electromechanical coupling factors in planar (k_p) and thickness (k_t) modes of 15 and 45%, respectively.