Characterization of 0.74(Bi0.5Na0.5)TiO3-0.26SrTiO3 Lead-Free Piezoceramic Fabricated via Conventional and Microwave Sintering

Fabrication of 0.74(Bi0.5Na0.5)TiO3-0.26SrTiO3 (abbreviated as BNST26) ceramics via both conventional furnace sintering (CFS) and microwave sintering (MWS) was investigated in this work. MWS at 1100°C for 5 min resulted in ceramic with density comparable to that of ceramic fabricated via CFS at 1175°C for 2 h. Average grain sizes of 3.2 μm and 2.4 μm were calculated for the ceramics prepared by CFS and MWS, respectively, which was attributed to the lower temperature and shorter sintering time for MWS compared with CFS. In order to investigate the effect of sintering method on the electrical properties of the prepared ceramics, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were explored. The results revealed that the remanent polarization (Pr) and coercive field (Ec) of the ceramic prepared by MWS at 1100°C for 5 min were comparable to those of the ceramic under CFS at 1175°C for 2 h. However, the maximum polarization (Pmax) of the CFS ceramic was higher than that of the MWS ceramic. In the case of electric field-induced strain, there was no considerable difference between the MWS and CFS ceramics, and normalized strain d33* = 501 pm/V was obtained for the MWS ceramic at 1100°C, indicating the effectiveness of MWS for fabrication of BNT-based piezoceramics at lower temperature and shorter time versus CFS.