Dielectric and Piezoelectric Properties of Microwave Sintered BNT-ST Ceramics

This study investigated the microstructure and piezoelectric properties of lead-free 0.74(Bi1/2Na1/2)TiO3-0.26SrTiO3 (BNST26) piezoelectric ceramics sintered using a microwave furnace. For comparison, specimens were also prepared using a conventional furnace sintering (CFS). Average grain sizes of 2.4 μm and 3.2 μm were obtained in the sample sintered at 1,100°C for 5 min using microwave sintering (MWS) and at 1,175°C for 2 h using CFS, respectively. To quantify the changes in the microstructures and electrical properties according to the sintering conditions, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were evaluated. As a result, it was determined that the Pmax (maximum polarization), Pr (remanent polarization) and Smax (maximum strain) values tend to increase with the average grain size. Based on these results, it is concluded that the MWS method can produce lead-free ceramics with superior performance in a relatively short time compared to the conventional CFS method.