(1-x)K0.48Na0.52NbO3-xBi0.45Nd0.05(Na0.92Li0.08)0.5ZrO3无铅压电陶瓷相结构及压电性能

为了在获得较高压电性能的同时又不大大降低陶瓷的居里温度(T_C), 设计和制备了Bi_0.45Nd_0.05(Na_0.92Li_0.08)_0.5ZrO₃改性的K_0.48Na_0.52NbO₃系无铅压电陶瓷((1-x)KNN-xBNNLZ), 研究了BNNLZ含量对KNN基无铅压电陶瓷相结构和电学性能的影响。研究结果表明, 所有陶瓷样品均具有较高的居里温度T_C(>300℃)。随着BNNLZ含量的增加, 陶瓷的正交-四方相变温度(T_O-T)不断向低温方向移动, 而三方-正交相变温度(T_R-O)不断向高温方向移动, 最终在陶瓷中形成了三方-四方(R-T)共存相, R-T共存相处于0.05<x<0.07范围。BNNLZ的加入引起陶瓷相结构的演化改变导致压电常数(d₃₃ )、介电常数(ε_r )、剩余极化强度 (P_r )和机电耦合系数(k_p )都先增大后减小, 当x=0.06时陶瓷具有最佳压电性能: d₃₃=313 pC/N, k_p=42%, P_r=25.48 μC/cm², ε_r=1353, tanδ=2.5%, T_C=327℃。

Phase Structure and Piezoelectric Property of (1-x)K0.48Na0.52NbO3-xBi0.45Nd0.05(Na0.92Li0.08)0.5ZrO3 Lead-free Piezoceramics

To enhance the piezoelectric properties and maintain relatively higher Curie temperature (T_C), (1-x)K_0.48 Na_0.52 NbO₃-x Bi_0.45 Nd_0.05 (Na_0.92Li_0.08)_0.5ZrO₃ ((1-x) KNN-xBNNLZ) ceramics were prepared by conventional solid-state method. The effects of BNNLZ content on the phase structure and electrical properties of the ceramics were investigated in details. The results show that all ceramic samples exhibit higher T_C (>300℃). With the increase of BNNLZ content, both orthorhombic-tetragonal phase transition temperature (T_O-T) and rhombohedral-orthorhombic phase transition temperatures (T_R-O) shift to room temperature simultaneously, and finally the R-T phase coexistence is constructed near room temperature in the compositions range of 0.05<x<0.07. The phase transitions of the ceramics caused by BNNLZ addition lead to values of d₃₃, ε_r, P_r, and k_p increase firstly and then decrease. The ceramic with x=0.06 exhibits optimal properties: d₃₃=313 pC/N, k_p=42%, P_r=25.48 μC/cm², ε_r=1353, tanδ=2.5%, together with a higher T_C of 327℃.