B2O3 doping in 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 lead-free piezoelectric ceramics

Abstract The effects of B 2 O 3 doping on the dielectric and piezoelectric properties of 0.94(Bi 0.5 Na 0.5 ) TiO 3 -0.06BaTiO 3 (BNT-6BT) ceramics were investigated. Pre-reacted BNT-6BT powders synthesized by solid state reaction method were doped with B 3+ ions in 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1, and 2 mol%. All samples were sintered at 1150 °C for 12 h in air. The effects of boron doping on structure and electrical properties were characterized as a function of dopant concentration. The results indicate a substantial increase in piezoelectric coefficient ( d 33 ), dielectric constant ( e r ), and dielectric loss ( tan δ ) approximately 19%, 42%, and 95%, respectively. The positive effects of doping were more significant in BNT-6BT samples with 0.3% and more B 2 O 3 addition. The highest piezoelectric coefficient was obtained as d 33 =173 pC/N in 1% doped BNT-6BT. In terms of dielectric properties, both e r and tan δ values increased with B 3+ % reaching 1075 and 0.0421, respectively in 2% doped samples. Even though the measured density values remain relatively unchanged, the increase of all these coefficients together implies a donor dopant role of B 3+ ions.