K4CuNb8O23掺杂对K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3压电陶瓷性能的影响

采用固相反应法制备了K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3+xmol%K4CuNb8O23(0≤x≤2)(简称LF4-KCN)无铅压电陶瓷,使用XRD、SEM、Agilent4294A精密阻抗分析仪等对该体系的相组成、显微结构、压电及介电等性能进行表征。XRD分析表明,随着KCN含量的增加,室温时样品由四方相向正交相转变,且当x≥1时,出现K6Li4Nb10O30杂相。SEM分析表明,掺入KCN后,样品晶粒尺寸减小,晶粒轮廓清晰。随着KCN含量的增加,在100℃附近的介电常数温度曲线上出现第二介电常数极大值,即正交→四方铁电相变温度TO-T,同时居里温度TC向低温方向移动。KCN掺杂量对LF4的电性能有很大影响,表现为"硬性"掺杂,其压电常数d33,平面机电耦合系数kp,1kHz频率下的介电损耗tanδ和介电常数εr均随着KCN含量的增加而降低,而机械品质因素Qm整体提高,样品的密度也显著增大。

Effect of K4CuNb8O23 Doped on the Properties of K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3 Piezoelectric Ceramics

The K_(0.44)Na_(0.52)Li_(0.04)Nb_(0.86)Ta_(0.10)Sb_(0.04)O_3+x mol%K_4CuNb_8O_(23)(0≤x≤2)(abbreviated as LF4-KCN) lead-free piezoelectric ceramics were fabricated by solid state reaction. The phase, microstructure, electric properties of the samples were characterized by XRD, SEM and Agilent 4294A impedance analyzer. XRD result shows that the phase of the sample transforms from tetragonal into orthorhombic with the increasing of KCN content. When x≥1, the trace amount of second phase K_6Li_4Nb_(10)O_(30) can be detected. SEM shows that the grain size of those materials decreases as the KCN content increasing, and the figure of the grain becomes clearly. There is another dielectric constant maximum value around 100 ℃, which is the phase transition from orthorhombic to tetragonal (T_(O-T)), while the curie temperature (TC) shifts to higher temperature. The KCN-doping has great influence on the electrical properties, the ceramic becomes "hardened", the piezoelectric constant (d_(33)), electromechanical planar coupling coefficients(kp), the dielectric constant(ε_r) and dielectric loss(tanδ) at 1 kHz decrease as the KCN content increasing. The mechanical quality factor (Q_m) and the density increases significantly.