Room‐Temperature Symmetric Giant Positive and Negative Electrocaloric Effect in PbMg_0.5W_0.5O₃ Antiferroelectric Ceramic

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.