Room‐Temperature Symmetric Giant Positive and Negative Electrocaloric Effect in PbMg<sub>0.5</sub>W<sub>0.5</sub>O<sub>3</sub> Antiferroelectric Ceramic
Junjie Li, Hong‐Hui Wu, Jianting Li, Xiaopo Su, Ruowei Yin, Shiqiang Qin, Dong Guo, Yanjing Su, Lijie Qiao, Turab Lookman, Yang Bai
Abstract
Abstract As an emerging solid‐state refrigeration technology with zero‐emission and high energy conversion efficiency, there is a compelling need for ferroelectric materials with giant electrocaloric effects (ECEs) at room temperature suitable for refrigeration applications. The complex perovskite antiferroelectric (AFE), PbMg 0.5 W 0.5 O 3 , containing non‐equivalent B‐site ions with a symmetric giant positive and negative ECE near room temperature is presented. At the Curie temperature of 36 °C, the first‐order AFE–paraelectric phase transition gives rise to a large enthalpy change of 3.92 J g −1 , more than four times that of BaTiO 3 . This leads to a significant ECE under the influence of an electric field. The direct electrocaloric characterization shows that the adiabatic temperature change, Δ T , exhibits symmetric peaks with a giant positive maximum of 1.79 K (Δ S = 1.68 J kg −1 K −1 ) at 36 °C and a negative maximum of −2.02 K (Δ S = −1.93 J kg −1 K −1 ) at 34 °C. The ultrahigh magnitude of Δ T near room temperature makes PbMg 0.5 W 0.5 O 3 a superior electrocaloric material far beyond traditional PbZrO 3 ‐based AFEs. The coexistence of symmetric giant positive and negative Δ T to further improve cooling efficiency is expected. In addition, the good reversibility and negligible leakage current should pave the way for practical applications.