采用传统陶瓷的制备方法,制备出(1-x)Na0.44K0.06Bi0.5TiO3-xNaNbO3(x=0~0.10)的无铅压电陶瓷。X一射线衍射(XRD)分析表明,所研究的组成均形成纯钙钛矿(ABO3)型固溶体,其晶体结构则随NaNbO3含量的增加由三方转变为假立方结构,并最终转变为立方结构。陶瓷材料的介电常数-温度曲线显示该体系材料为弛豫型铁电体,随着NaNbO3的增加,材料的弛豫性增强;采用改进的居里-外斯定理可较好地描述材料的介电常数-温度关系。测试了不同组成陶瓷的压电性能,当NaNbO5含量为0.08mol时,陶瓷的压电常数d33和平面机电耦合系数kp比基础组成略有下降,但其介电常数ε33^T/ε0和介质损耗tanδ则有较大程度的增加。
The ( 1 - x) Na0.44 K0.0s Bi0.5 TiO3-x NaNbO3 (x = 0 - 0. 10) lead-free piezoelectric ceramics were fabricated by conventional ceramics technique. The crystalline structure of all compositions is mono-perovskite phase ascertained by XRD. The crystalline symmetry varied from rhombohedral to pseudo-cubic,and then to cubic at x = 0.10. The dielectric constant as function of temperature showed that all specimens were relaxor ferroelectric, and the relaxation character increased with the amount of NaNbO3. The relation between dielectric constant and temperature could be characterized well by modified Curie-Weiss law. When x = 0.08 mol, the piezoelectric properties indicated the piezoelectric constant daa and planar electromeehanieal coupling factor kp, decreased a little, while the dielectric constant ε33^T/ε0 and dielectric loss tan δ improved much more.