中文摘要：

采用常压烧结方法制备了Mn掺杂的（K0.5Na0.5）0.96Sr0.02Nb1-xMnxO3无铅压电陶瓷.研究了Mn含量对该体系材料的相组成、微观结构、介电、压电和热稳定性能的影响.XRD表明随着Mn含量的增加,体系由正交相过渡到赝四方相;而且,富Na的第二相消失,得到纯净的钙钛矿相结构.在Mn含量为x=0.03和0.04时,观察到了两个温度（200和390℃）处的介电反常,这和晶格畸变引起的复晶胞结构有关.Mn含量为x=0.02时,得到综合性能优良的压电超声换能器用材料：介电常数ε^T33/ε0=479,压电常数d33=121pC/N,机电耦合系数Kp=41%,机械品质因子Qm=298,介电损耗tanδ=1.6%,居里温度Tc=391℃,谐振频率αfr和机电耦合系数Kp随温度的变化率αfr（80℃）和αKp（80℃）分别为-1.85%和1.19%.

英文摘要：

Dense lead free ceramics of （Ko.sNa0.5）0.96Sr0.02Nb1-xMnxO3 （z=0,0.01,0.02,0.03,0.04）were successfully prepared by a conventional mixed oxide method. The X-ray diffraction patterns revealed pure peroveskite structure after Mn doping as compared to the original composition. This was attributed to the inhibition of K^＋ volatility during sintering process. Dielectric anomaly was observed and explained by multiple-cell structure resulting from Mn-induced lattice distortion. Low loss tangent and relatively high planar electromechanical coupling factor were obtained at x=0.02. The main parameters for the composition of x=0.02 are：ε^T33/ε0=479,d33=121pC/N Kp=41%,Qm=298,tanδ=1.6%,Tc=391℃The rates of resonant frequency variation,αfr and planar coupling factor variation,αKp with temperature are 1.85% and 1.19% at 80℃, respectively. This material may be suitable for applications in ultrasonic transducers.