Bi_0.5Na_0.5TiO₃ (BNT)-based ceramics are one of the most promising lead-free ferroelectrics due to their high strain property. Compared to other chemical modifications, rare earth ions doping provides significant possibility to optimize the strain property of BNT-based ceramics. In this work, the effects of rare earth ions on phase structure, microstructure, and strain & electrostrictive properties of lead-free BNT-based ceramics were systematically investigated. Rare earth ions (i.e., La³⁺, Sm³⁺, Yb³⁺, Dy³⁺, and Nd³⁺) were selected as the doping ions. Introducing moderate La³⁺ ions can drive the ferroelectric state of BNT-based ceramics to nonergodic relaxor state or ergodic relaxor state. The enhanced strain response of ∼0.40–0.42% and high converse piezoelectric coefficient of ∼600–630 pm/V can be achieved under 60–70 kV/cm for La³⁺-doped ceramic with nonergodic relaxor state. Besides, the giant electrostrictive coefficient Q₃₃ of ∼0.047 m⁴/C² can be obtained for La³⁺-doped ceramic with ergodic relaxor state. Other rare earth ions also present the promotion effect on strain enhancement for BNT-based ceramics. This study affords a significant guidance to optimize strain and electrostrictive properties of BNT-based ceramics via rare earth ions doping.

Bi _0.5 Na _0.5 TiO ₃ (BNT)基陶瓷由于其高应变特性而成为最有前途的无铅铁电体之一。与其他化学改性相比，稀土离子掺杂为优化 BNT 基陶瓷的应变性能提供了重要的可能性。在这项工作中，系统研究了稀土离子对无铅BNT基陶瓷的相结构、微观结构以及应变和电致伸缩性能的影响。选择稀土离子（即La ³⁺、Sm ³⁺、Yb ³⁺、Dy ³⁺和Nd ³⁺）作为掺杂离子。引入中度 La ³⁺离子可以将BNT基陶瓷的铁电态驱动到非遍历弛豫状态或遍历弛豫状态。^{在 60-70 kV/cm 下，对于具有非遍历弛豫状态的 La 3+}掺杂陶瓷，可以实现 ∼0.40-0.42% 的增强应变响应和 ∼600-630 pm/V 的高逆压电系数。此外，对于具有遍历弛豫状态的La ³⁺掺杂陶瓷，可以获得~0.047 m ⁴ /C ²的巨电致伸缩系数Q _{33 。}其他稀土离子对 BNT 基陶瓷的应变增强也有促进作用。该研究为通过稀土离子掺杂优化BNT基陶瓷的应变和电致伸缩性能提供了重要指导。