采用固相法制备了 Na0.5Bi0.5TiO3–K0.5Bi0.5TiO3–BaTiO3–SrTiO3(NBT–KBT–BT–ST)陶瓷,该体系是按(1–2x)(0.8NBT–0.2KBT)–x(0.94NBT–0.06BT)–x(0.74NBT–0.26ST) (x = 0.10、0.20、0.25、0.30、0.35、0.40、0.45)组合而成的,研究了该系陶瓷的结构与电性能。结果表明:所有样品都处于三方–四方准同型相界区域。该系陶瓷在准同型相界附近表现出了优异的压电性能,压电常数 d33、机电耦合系数 kp和剩余极化强度 Pr随 x 的增加先升高后降低,其中 x=0.35 陶瓷的电性能最佳:d33= 210 pC/N,kp= 0.319,Pr= 39.3 μC/cm2,Ec= 20.2 kV/cm,是一种良好的无铅压电陶瓷候选材料。依据准同型相界组成的线性组合规律来寻找具有优异压电性能的 NBT–KBT–BT–ST 陶瓷准同型相界组成是可行的。
Nao.sBi0.5TiO3-K0.5Bi0.5TiO3-BaTiO3-SrTiO3 (NBT-KBT-BT-ST) lead-free piezoelectric ceramics with the compositions of (1-2x)(0.8NBT-0.2KBT)-x(0.94NBT-0.06BT)-x(0.74NBT-0.26ST)(x=0.10, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45) were fabricated by a solid state reaction method. The structure and electrical properties for NBT-KBT-BT-ST samples were investigated. The mor- photropic phase boundary (MPB) between the rhombohedral and tetragonal phases was identified in all the samples. The results demonstrate that such ceramic systems near the MPB exhibit superior electrical properties. The piezoelectric constant d33, electrome- chanical planar coupling factor Kp and remanent polarization Pr firstly increased and then decreased with the increase ofx. The opti- mum electric properties (d33 = 210 pC/N, kp = 0.319, Pr= 39.3 μC/cm2, Ee = 20.2 kV/cm) could be obtained for a composition with x = 0.35. It is suggested that NBT-KBT-BT-ST with the composition (x = 0.35) could be a candidate material for lead-free applications. Therefore, the MPB linear combination rule could be used to search for the composition neear MPB with the excellent properties of NBT-KBT- BT-ST ceramics.