Lin Weikang, Li Guohui, Qian Jin, Ge Guanglong, Wang Simin, Lin Jinfeng, Lin Jimin, Shen Bo, Zhai Jiwei
Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804, China.
ACS Nano. 2024 May 21;18(20):13322-13332. doi: 10.1021/acsnano.4c03127. Epub 2024 May 10.
Lead-free electrocaloric (EC) ferroelectrics are considered ideal for the next generation of environmentally friendly solid-state refrigeration materials. However, their inferior performance compared to lead-based materials significantly restricts their potential application. According to phase-field simulations, it is predicted that the pinning effect of a moderate number of defects can effectively enhance the reversible polarization response associated with the entropy change. Herein, sodium-bismuth titanate (BNT) ceramics with high spontaneous polarization are selected to construct B-site defects by introducing Li and Nb. Under an electric field of 6 kV mm, ultrahigh EC temperature changes of Δ = 1.77 and Δ = 1.49 K are achieved at 65 °C by direct measurement (Δ > 1 K over 55-120 °C). Furthermore, Δ remains above 0.70 K in the temperature range from 25 to 130 °C, exhibiting immense potential for practical applications. This study offers a promising direction for optimizing the EC response in defect systems.
无铅电热（EC）铁电体被认为是下一代环保型固态制冷材料的理想选择。然而，与铅基材料相比，它们较差的性能严重限制了其潜在应用。根据相场模拟，预计适量数量的缺陷的钉扎效应可以有效增强与熵变相关的可逆极化响应。在此，选择具有高自发极化的钛酸铋钠（BNT）陶瓷通过引入Li和Nb来构建B位缺陷。在6 kV/mm的电场下，通过直接测量在65°C时实现了超高的EC温度变化ΔT = 1.77和ΔT = 1.49 K（在55 - 120°C范围内ΔT > 1 K）。此外，在25至130°C的温度范围内ΔT保持在0.70 K以上，展现出巨大的实际应用潜力。这项研究为优化缺陷系统中的EC响应提供了一个有前景的方向。
