采用固相法制备了(1-x)(Na0.9K0.1)0.5Bi0.5TiO3-(Ba0.7Ca0.3)TiO3[(1-x)NKBT-xBCT]无铅压电陶瓷。研究了不同BCT含量(x=0,0.02,0.04,0.05,0.06,0.07)对NKBT陶瓷结构与电性能的影响。结果表明:所有样品均形成纯的钙钛矿结构,体系陶瓷的准同行相界(MPB)位于0.04≤x≤0.06。随着BCT掺量的增加,样品的退极化温度乃逐渐向低温方向移动,压电常数d3,和平面机电耦合系数k。均先升高后降低。系列陶瓷电性能较佳:x=0.05时,kp最大,为0.29。当x=0.06时,样品的综合性能较好,其中d33=168pC/N,kp=0.26,相对介电常数εr=1280,介质损耗tan6=3.7%,剩余极化强度Pt=37μC/cm^2,矫顽场Ec=18.8kV/cm。变温电滞回线和介电温谱表明体系陶瓷在死以上可能存在极性相与非极性相共存。
Lead-free piezoelectric ceramics (Na0.9K0.1)0.5Bi0.5TiO3-(Ba0.7Ca0.3)TiO3 [ ( 1 - x) NKBT- xBCT] were prepared by solid state reaction method. The effects of different BCT content on the structure and electrical properties of ceramic samples were investigated. The results show ( 1 - x) NKBT-xBCT materials possess the pure perovskite structure. The morphotropic phase boundary (MPB) of the system locates in the composition range of 0.04 ≤ x ≤ 0.06. Both of the piezoelectric constant d33 and planar coupling factor kp of ceramics first increase and then decrease, and the depolarization temperature Td decrease with the increasing of BCT content. The series ceramics exhibit good electrical properties : the best kp = 0.29 at x = 0.05, and when x = 0.06, the ceramic exhibits an optimum performance : d33 = 168 pC/N, kp = 26%, relative dielectric constant ε = 1280, dielectric loss tanδ - 3.7%, remnant polarization Pr = 37℃/cm2, coercive field Ec = 18.8 kV/cm. The temperature dependences of ferroelectric and dielectric properties suggest that the ceramics may contain both the polar and non-polar regions at temperatures above Td.