Enhanced electrical properties of lead-free BNLT–BZT ceramics by thermal treatment technique

Electrical properties of lead-free solid solution ceramics from the Bi0.4871Na0.4871La0.0172TiO3 (BNLT) and BaZr0.05Ti0.95O3 (BZT) system have been improved by a thermal treatment technique. A modified two step mixed-oxide method was employed for the preparation of the (1−x)BNLT–xBZT ceramics, where x=0.06, 0.09, 0.12 and 0.20. After sintering at 1125 °C for 4 h, the BNLT–BZT ceramics were annealed at 825, 925 and 1025 °C. The annealing treatment caused an increase in dielectric constant of BNLT–BZT ceramics with x≤0.09 mol% and with x higher than 0.09 mol% the dielectric value dropped considerably. The ferroelectric properties of all annealed ceramic samples tend to decrease with increasing annealing temperature as confirmed by the slimmer P–E loops. The piezoelectric coefficient (d33) increased with annealing temperatures and a maximum value of ∼170 pC/N was obtained from the ceramic samples annealed at 1025 °C with x=0.02.