Low-temperature sintered Bi0.5Na0.5TiO3-SrTiO3 incipient piezoceramics and the co-fired multilayer piezoactuator thereof

Lead-free Bi0.5Na0.5TiO3-SrTiO3 incipient piezoceramics with Li2CO3 and MnO2 additives were successfully fabricated at low firing temperature for applications in co-fired multilayer piezoactuators. The addition of Li2CO3 effectively shifted the sintering temperature from 1230 °C down to 1075 °C, where the ceramics were co-fired with a Ag/Pd (75/25) inner electrode. The prototype actuators were prepared by tape-casting method using ceramics with the composition of 0.74Bi0.5Na0.5TiO3-0.26 SrTiO3 + 0.15 wt%MnO2 + 0.45 wt%Li2CO3. The total number of active layers was 13, and each ceramic layer had a thickness of 60 μm. The actuator output a large strain up to ∼0.20% at a driving field of 4 kV/mm, due to the field-induced phase transition between the ergodic relaxor and ferroelectric phases. The excellent voltage-displacement performance of the prototype actuator demonstrates the potential for industrial applications.