Effect of Bi₂O₃ addition and sintering time on the physical and electrical properties of lead-free (Na_0.5Bi_0.5)TiO₃-Ba(Zr_0.04Ti_0.96)O₃ ceramics

抄録

Although PbZrO₃-PbTiO₃ (PZT)-based ceramics are playing a dominant role in piezoelectric materials, their evaporation of harmful lead oxide during the sintering process causes a crucial environment problem. It is necessary to search for lead-free piezoelectric materials that have such excellent properties as those found in the PZT-based ceramics. Therefore (Na_0.5Bi_0.5)TiO₃-based solid solutions were studied to improve piezoelectric properties. In the present study, various quantities of Bi₂O₃ were added into 0.99(Na_0.5Bi_0.5)TiO₃-0.01Ba(Zr_0.04Ti_0.96)O₃ (0.99NBT-0.01BZT) ceramics. High-density samples were obtained through the addition of Bi₂O₃ into 0.99NBT-0.01BZT ceramic. It was found that 0.99NBT-0.01BZT with the addition of 0-4.0 wt% Bi₂O₃ exhibit relatively good piezoelectric properties. For 0.99NBT-0.01BZT ceramic with the addition of 0.5 wt% Bi₂O₃, the electromechanical coupling coefficients of the planar mode k_p and the thickness mode k_t reach 0.15 and 0.55, respectively, at the sintering of 1100°C for 2 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.6. It is obvious that 0.99NBT-0.01BZT solid solution ceramic by adding low quantities of Bi₂O₃ is one of the promising lead-free ceramics for high frequency electromechanical transducer applications.