高性能压电陶瓷，特别是性能可与单晶相媲美的压电陶瓷的开发，是压电材料研究者孜孜以求的目标。通过组分设计使陶瓷位于准同型相界附近和通过稀土离子掺杂增强局部结构异质性是两种在钙钛矿压电陶瓷中获得优异压电性能的方法。在所有稀土离子中，钐离子（Sm3+）是最有效的构筑局部异质结构的离子。在Sm3+掺杂铅基钙钛矿压电陶瓷中，可实现准同型相界和增强局部结构异质性两种机制协同作用，有效增强压电性能。稀土Sm3+离子掺杂会引入缺陷，而缺陷在调控压电性能中起到至关重要的作用。因此，深入研究稀土Sm3+离子掺杂的铅基压电陶瓷中缺陷的变化规律以及缺陷对电学性能的影响具有重要意义。 本文采用固相烧结法制备了铅基压电陶瓷，包括Pb[(Mg1/3Nb2/3)(1-x)Tix]O3(PMN-xPT)、Pb(1-x)Smx[(Mg1/3Nb2/3)0.68Ti0.32](1-x/4)O3(xSm-0.68PMN-0.32PT)、Pb(1-x)Smx[(Mg1/3Nb2/3)0.71Ti0.29](1-x/4)O3(xSm-0.71PMN-0.29PT)、Pb(1-x)Smx[(Mg1/3Nb2/3)0.15Zr0.43Ti0.42](1-x/4)O3 (xSm-PMN-PZT(43/42))、Pb(1-x)Smx(Zr0.54Ti0.46)(1-x/4)O3(xSm-PZT(54/46))，对制备的陶瓷进行了XRD、SEM微观形貌表征，同时进行介电、压电、铁电等电学性能表征，分析材料中的缺陷对材料电学性能的影响，结论如下： 在xSm-PMN-PT中，与未掺杂的PMN-xPT相比，压电性能显著增强。xSm-0.68PMN-0.32PT体系中最大压电系数出现在x=0.025，d33=1004pC/N，掺杂使压电系数增大71.6%；在xSm-0.71PMN-0.29PT体系中最大压电系数出现在x=0.01，d33=1004pC/N，掺杂使压电系数增大了224%。Sm掺杂也使体系的介电性能增强，但其铁电性能却劣化。分析表明，在未掺杂的PMN-xPT中，最优压电性能与其中较高的A位空位浓度促进畴壁运动有关；而在Sm掺杂的PMN-PT中，压电性能增强则与掺杂引入的B位空位有关，适度提高B位相对A位缺陷的比例I1/I2有益于增强压电性能。 在xSm-PMN-PZT（43/42）和xSm-PZT（54/46）体系中，Sm掺杂也使压电性能增强，但其性能远不如xSm-PMN-PT。xSm-PMN-PZT（43/42）体系中最大压电系数出现在x=0.02，d33=383pC/N，Sm掺杂也使体系的介电性能增强，但其铁电性能却劣化，这与掺杂改变了体系中A位与B位缺陷的比例有关；xSm-PZT（54/46）体系中最大压电系数出现在x=0.01，d33=572pC/N，压电系数提高了近一倍，Sm掺杂也使介电性能增强，但剩余极化2Pr却随着Sm掺杂量x增大呈现出先增大后减小的趋势，这与该体系中缺陷类型改变有关，x=0、0.03和0.04陶瓷中出现了缺陷偶极子，对畴壁具有强烈钉扎作用，使压电、介电和铁电性能变差。

The development of high performance piezoelectric ceramics, especially those whose piezoelectric performance is comparable to that of single crystal, is always desired by the researchers in this field. There are two main techniques available for achieving the high piezoelectric response:locating the compositions at or near morphotropic phase boundary (MPB), where the rhombohedral and tetragonal phases coexist and result in easily domain reorientation during poling, by composition design;improving the local structural heterogeneity by rare earth ion doping, which can flatten the thermodynamic energy profile. Among all rare earth ions, samarium ion (Sm3+) is the most effective ion to induce local heterostructures. In Sm3+-doped Pb-based perovskite piezoceramics, piezoelectric properties are improved by synergistic contributions from MPB and enhanced local structural heterogeneity. Rare earth Sm3+ ion doping will introduce defects, which plays an important role in regulating piezoelectric properties. Therefore, it is of great significance to study the variation of defects and the effect of defects on electrical properties in Sm3+ ions doped lead based piezoelectric ceramics. In this paper, Sm3+-doped Pb-based piezoelectric ceramics, including Pb[(Mg1/3Nb2/3)(1-x)Tix]O3(PMN-xPT), Pb(1-x)Smx[(Mg1/3Nb2/3)0.68Ti0.32](1-x/4)O3(xSm-0.68PMN-0.32PT), Pb(1-x)Smx[(Mg1/3Nb2/3)0.71Ti0.29](1-x/4)O3(xSm-0.71PMN-0.29PT), Pb(1-x)Smx[(Mg1/3Nb2/3)0.15Zr0.43Ti0.42](1-x/4)O3(xSm-PMN-PZT(43/42)), Pb(1-x)Smx(Zr0.54Ti0.46)(1-x/4)O3(xSm-PZT(54/46)), were preparedwith solid-state sintering method. The microstructures andelectrical properties were investigatedby XRD and SEM, and dielectric, piezoelectric, ferroelectric test. The defect information in ceramics was obtained using positron annihilation techniques (PAT),including positron annihilation lifetime spectroscopy (PALS) and Coincidence Doppler Bro-adening energy spectroscopy (CDB). The effect of microstructure defects on elelctrocal properties was analyzed. The conclusions are as follows: In comparison with undoped PMN-PT ceramics, the piezoelectric properties of Sm-doped PMN-PT ceramics are significantly enhanced. In xSm-0.68PMN-0.32PT, the optimal piezoelectric coefficient appears at doping amount x=0.025, d33=1004pC/N,which increases by 71.6% in comparison with undoped 0.68PMN-0.32PT (the MPB composition of PMN-PT) ceramics. In xSm-0.71PMN-0.29PT, the optimized piezoelectric coefficient appears at doping amount x=0.01, d33=1004pC/N, which increases by 224% in comparison with undoped 0.71PMN-0.29PT ceramics. In both systems, Sm doping enhances the dielectric properties of the system, but degrades its ferroelectric properties. It is inferred that the maximum piezoelectric coefficient of undoped PMN-PT is related to the much higher concentration of A-site Pb vacancy, which promotes the domain wall movement.In contrast, the enhancement of piezoelectric properties in Sm-doped PMN-PT ceramics is associated with B-site defects introduced by Sm doping. It is beneficial to enhancing piezoelectric properties by properly increasing I1/I2, which indicates the ratio of B-site to A-site defects . In xSm-PMN-PZT(43/42) and xSm-PZT(54/46) systems, Sm doping also enhances the piezoelectric properties, but their piezoelectric performances are much inferior to that of xSm-PMN-PT. In xSm-PMN-PZT(43/42) system, the maximum piezoelectric coefficient appears at x=0.02, d33=383pC/N. Like Sm-PMN-PT, Sm doping also enhances the dielectric properties of the system, but its ferroelectric properties deteriorate, which is related to the change of the ratio of A-site to B-site defect in the system. In xSm-PZT(54/46) system, the maximum piezoelectric coefficient appears at x=0.01, d33=572pC/N, and the piezoelectric coefficient increases nearly twice. Sm doping also enhances the dielectric properties, but the residual polarization 2Pr increases first and then decreases with the increase of Sm doping amount x, which is related to the change of defect types in the system. The presence of defect dipoles in x=0, 0.03, and 0.04 ceramics strongly pins the domain walls, resulting in poor piezoelectric, dielectric, and ferroelectric properties.

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