一步法合成的2.0%Sm-0.25Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.75Pb(Zr_(1-x)Ti_(x))O_(3)压电陶瓷的压电性能

Piezoelectric Properties of 2.0%Sm-0.25Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.75Pb(Zr_(1-x)Ti_(x))O_(3)Ceramics Prepared by One-step Method

通常采用两步合成法制备铌镁酸铅-锆钛酸铅(Pb(Mg_(1/3)Nb_(2/3))O_(3)-Pb(Zr,Ti)O_(3),PMN-PZT)压电陶瓷,即先合成MgNb_(2)O_(6)前驱体。工业生产中,两步法生产效率相对较低,成本高,并影响产品性能的一致性。本工作通过高效及低成本的一步合成法,研制了高致密度和高压电性能的2.0%(摩尔分数,下同)Sm-0.25Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.75Pb(Zr_(1-x)Ti_(x))O_(3)(Sm-PMN-PZT)压电陶瓷。在x=0.52~0.53范围内,构建了三方相、四方相(R-T)共存的准同型相界(MPBs);Sm3+的引入增强了局域结构异质性,外电场下铁电相变的势垒较低,即自由能曲线的曲率最小,压电性能得到优化。当x=0.525时,陶瓷具有最优的综合电学性能,压电系数d33=645 pC/N,机电耦合系数k_(p)=0.657,相对介电常数ε_(r)=3110,介电损耗tan=1.78%,居里温度T_(C)=242℃。采用瑞利定律分析可知,晶格贡献和可逆畴壁运动的内部压电响应,以及不可逆畴壁运动的外部压电响应均得到提高是该组分陶瓷获得高压电性的重要原因。

Niobium magnesium-lead zirconate titanate(Pb(Mg_(1/3)Nb_(2/3))O_(3)-Pb(Zr,Ti)O_(3),PMN-PZT)ceramics are usually prepared by a two-step synthesis method where the MgNb_(2)O_(6)precursor needs to be synthesized firstly.In industrial production,the two-step synthesis method has relatively low production efficiency and high cost and affects the consistency of product performance.In this work,2.0mol%Sm-0.25Pb-(Mg_(1/3)Nb_(2/3))O_(3)-0.75Pb(Zr_(1-x)Ti_(x))O_(3)(Sm-PMN-PZT)piezoelectric ceramics with high density and high piezoelectric properties were prepared by a one-step synthesis method with high efficiency and low cost.In the range of x=0.52-0.53,the morphotropic phase boundaries(MPBs)with the coexistence of rhombohedral(R)and tetragonal phases(T)were constructed.Introduction of Sm3+enhances the heterogeneity of local polar structures,decreases the potential barrier required for the transition of R-T phase under external electric field(Eex),minimizes the curva-ture of the free energy curve and finally improves the piezoelectric properties.The ceramic at x=0.525 presents the best comprehensive electrical performance,such as piezoelectric coefficient d33=645 pC/N,the planar electromechanical coupling coefficient kp of 0.657,the relative dielectric constantεr of 3110,the dielectric loss tanδof 1.78%,and the ferroelectric Curie temperature TC of 242℃.Based on Rayleigh’s law analysis,it has been found that the ceramic at x=0.525 achieves the high piezoelectricity due to its intrinsic response of lattice contribution and reversible domain wall movement,and extrinsic piezoelectric response of irreversible domain wall movement both being enhanced.