| 초록 |
At present, lead zirconate titanate (PZT)-based ceramics are the most widely applied piezoelectric materials because of their superior properties. However the toxic lead of the PZT-based ceramics causes environmental problems. Therefore, lead-free piezoelectric materials such as (Bi0.5Na0.5)TiO3 (BNT)-based oxides have been receiving much attention to replace PZT-based ceramics. In this study, the overall characteristics of lead-free Bi0.5(Na1-xKx)0.5TiO3 ceramics such as dielectric, and piezoelectric properties were examined in the entire compositional range from x = 0.0 to x = 1.0. From the specimens prepared using a solid state reaction method, the rhombohedral-tetragonal morphotropic phase boundary (MPB) was confirmed by X-ray diffraction. The decreasing tendency in grain size as Bi0.5K0.5TiO3 increased was observed by scanning electron microscopy (SEM). The optimum values of piezoelectric constant (d33), dielectric constant (ε), and electromechanical coupling factor (KP) were obtained in the MPB region. In order to improve d33 further, the Nb doping effect was studied. |
