BaZrO3掺杂对(K0.49Na0.51)0.98Li0.02(Nb0.77Ta0.18Sb0.05)O3无铅压电陶瓷的结构与电性能的影响

Effect of BaZrO_3 Depant on the Structure and Electric Properties of (K_(0.49)Na_(0.51))_(0.98)Li_(0.02)(Nb_(0.77)Ta_(0.18)Sb_(0.05))O_3 Lead-free Piezoceramics

采用固相反应法制备了（K0.49Na0.51）0.98Li0.02（Nb0.77Ta0.18Sb0.05）O3-xBaZrO3（NKNLST-xBZ,x=0~0.020 mol）无铅压电陶瓷,系统研究了BaZrO3的掺杂量对陶瓷的压电、介电、机电和铁电性能的影响。结果表明：随着BaZrO3掺杂量x的增加,陶瓷的晶体结构由正交相向四方相转变,在x=0.005~0.008区间出现正交相与四方相两相共存的区域,在此区域内陶瓷的晶粒变得细小且均匀,介电损耗tanδ大幅降低,压电常数d33和平面机电耦合系数kp增加。该体系陶瓷的介电常数ε33T/ε0则随着BaZrO3的增加持续增加,相变温度则向低温方向移动。当x=0.005时,该组成陶瓷具有最佳的综合性能：压电常数d33=372 pC/N,平面机电耦合系数kp=47.2%,介电损耗tanδ=3.1%,以及较高的介电常数ε33T/ε0=1470和居里温度Tc=208℃。

（K0.49Na0.51）0.98Li0.02（Nb0.77Ta0.18Sb0.05）O3 （NKNLST-xBZ, x = 0-0.020 mol） lead-free piezoelectric ceramics were prepared by solid state reaction method. The effect of BaZrO3 doping amount on the piezoelectric, dielectric, electromechanical and ferroelectric properties were investigated systematically. The results revealed that the crystal structures transformed from orthorhombic phase to tetragonal phase with BaZrO3 doping amount increasing, and the coexistence of orthorhombic-tetragonal phases were observed in the x range from 0.005 to 0.008. Under the condition of two phases co-existence, the ceramic grain became small and uniform and dielectric loss tanO significantly decreased, while the piezoelectric constant d33 and planar electro-mechanical coupling factor kp increased. The dielectric constant ε33T/ε0 of this system ceramics increased continuously with the increase of the BaZrO3 doping amount and the phase transition temperatures shifted to lower temperature. The optimized piezoelectric properties could be obtained at the x = 0.005 composition ceramic as follows： the mized piezoelectric properties could be obtained at the x = 0.005 composition ceramic as follows constant d33 = 372 pC/N, planar electromechanical coupling coefficient kp = 47.2%, dielectric loss tan δ = 3.1%, a high dielectric constant ε33T/ε0 = 1470 and Curie temperature Tc=208℃.