(1-x)K0.49Na0.51NbO3-xLiNbO3无铅压电陶瓷的性能

Properties of (1-x)K_(0.49)Na_(0.51)NbO_3-xLiNbO_3 Lead-Free Piezoceramics

用传统固相烧结法制备(1-x)K0.49Na0.51NbO3-xLiNbO3(KNNLN,x=0.00～0.08,摩尔分数)体系无铅压电陶瓷。用X射线衍射仪及精密阻抗分析仪等研究不同掺量LiNbO3掺杂后对KNNLN体系陶瓷的晶体结构和电性能的影响。结果表明:在研究组成范围内,LiNbO3加入后能够形成单一钙钛矿结构的固溶体。随着LiNbO3的掺量的增加,晶体结构从正交转变为四方结构,并且经过由正交至四方多型相转变的过渡组成区域0.05≤x≤0.06。在过渡组成区域的四方相边界x=0.06处能够获得优异的电学性能:压电常数d33=246 pC/N,相对介电常数εr=679,机械品质因子Qm=52,平面机电耦合系数kp=41.6%。由于该组成陶瓷具有很高的Curie温度TC=467℃,因此适合应用于高温场合。

A（1-x）K0.49Na0.51NbO3-xLiNbO3（KNNLN,x=0.00-0.08,mole fraction） lead-free piezoceramic system was prepared by the traditional solid state reaction sintering method.The X-ray diffractometry and precision impedance analysis were employed to investigate influences of LiNbO3 dosages on crystal structure and electrical properties of the KNNLN ceramic system.Results indi-cate that full solid solution with a perovskite structure is formed after the LiNbO3 is added.By increasing the LiNbO3 content,the crystal structure is transformed from orthorhombic to tetragonal symmetry across a polymorphic phase transition（PPT） region with the composition range 0.05≤x≤0.06.Composition with x=0.06 on tetragonal side of the PPT region exhibits optimal electrical properties： piezoelectric constant d33=246 pC/N,relative dielectric constant εr=679,mechanical quality factor Qm=52,and planar electromechanical coefficient kp=41.6%.This ceramic sample has a very high Curie temperature TC=467 ℃,which means that it is suitable for high temperature applications.