Li-Ta改性KNN基无铅压电陶瓷结构与性能

Structures and Properties of Li-Ta-Modified KNN Lead-free Piezoelectric Ceramics

采用传统固相反应法成功制备出了(1-x)K0.48Na0.52NbO3-xLi(Ta0.5Nb0.5)O3无铅压电陶瓷。研究Li(Ta0.5Nb0.5)O3(LTN)对K0.48Na0.52NbO3材料晶体结构和压电性能的影响。结果表明,随LTN摩尔分数的增加陶瓷由正交钙钛矿相向四方钙钛矿相转变,陶瓷的准同型相界位于0.06<x<0.08处,且在x≥0.08时,出现钨青铜结构的第二相K3Li2Nb5O15;随LTN含量的增加,陶瓷的"正交-四方"铁电相变点TO-T逐渐向低温方向移动,居里温度TC向高温方向移动;材料的介电常数rε、压电常数d33、机电耦合系数kp均随LTN含量的增加先增大后减小。在x=0.07时,材料具有较好的压电性能:rε=856(1 kHz),d33=140 pC/N,kp=0.33,机械品质因数Qm=161,TC=440℃。

Lead-free piezoelectric ceramics（1-x）K0.48Na0.52NbO3-xLi（Ta0.5Nb0.5）O3 have been fabricated by the conventional solid phase reaction method.The effects of Li（Ta0.5Nb0.5）O3（LTN） on crystal structure and piezoelectric properties were investigated.The results showed that the perovskite structures of material transformed from the orthorhombic phase to the tetragonal phase as LTN content increased.The morphotropic phase boundary was formed at 0.06x0.08 and the second phase K3Li2Nb5O15 with tungsten bronze structure appeared at x≥0.08 at beginning and then became dominant with the content of LTN increasing.The ferroelectric phase transitional point of ＂orthorhombic to tetragonal＂ ceramic TO-T shifted to the lower temperature while the Curie temperature（TC） shifted to the higher temperature because of LTN content increasing.The dielectric constant（εr）,the piezoelectric constant（d33）,the electromechanical coupling coefficient（kp） increased at beginning and then decreased with the LTN content increasing.For the ceramic with x=0.07,the ceramic material had good piezoelectric properties with εr=856（1 kHz）,d33=140 pC/N and kp=0.33.The mechanical quality factor（Qm） was 161 and the Curie temperature（TC） was 440 ℃.