Field-driven merging of polarizations and enhanced electrocaloric effect in BaTiO3-based lead-free ceramics
Xiang Niu, Xiaodong Jian, Weiping Gong, Wei Liang, Xuetian Gong, Guangzu Zhang, Shenglin Jiang, Kun Yu, Xiaobo Zhao, Yingbang Yao, Tao Tao, Bo Liang, Sheng‐Guo Lu
Abstract
Abstract Solid-state cooling technology based on electrocaloric effect (ECE) has been advanced as an alternative to replace the vapour-compression approach to overcome the releasing of the global warming gases. However, the development in high ECE materials is still a challenge. In this work, polarization merging strategy was proposed to achieve a large ECE in x Ba(Sn 0.07 Ti 0.93 )O 3 -( 1 − x )Ba(Hf 0.1 Ti 0.9 )O 3 ferroelectric ceramics, where x = 0, 0.2, 0.4, 0.6, 0.8, and 1. Ba(Sn 0.07 Ti 0.93 )O 3 with an orthorhombic phase and Ba(Hf 0.1 Ti 0.9 )O 3 with a rhombohedral phase at room temperature were prepared beforehand as precursors, and phase-coexisted x BSnT-(1− x )BHfT ceramics were formed via a solid-state reaction approach. Phase coexisting structures were confirmed using the X-ray diffraction. The merged polarization was confirmed by the dielectric and ferroelectric properties. Optimal ECEs were obtained for 0.2BSnT-0.8BHfT ceramics, i.e., adiabatic temperature change Δ T = 2.16±0.08 K at 80 °C and 5 MV/m, and Δ T = 3.35±0.09 K at 80 °C and 7 MV/m.