Optimizing electrocaloric effect of PbSc <sub>0.5</sub>Ta <sub>0.5</sub>O <sub>3</sub> ceramics near/below room temperature by ordering degree modulation
Ruowei Yin, Yuxuan Hou, Lv Xiaowei, Junjie Li, Rongju Zhong, Yanjing Su, Lijie Qiao, Renchao Che, Li‐Feng Zhu, Chuanbao Liu, Yang Bai
Abstract
Lead scandium tantalate (PbSc<sub>0.5</sub>Ta<sub>0.5</sub>O<sub>3</sub>, PST) is one of the most promising ferroelectric materials for electrocaloric (EC) refrigeration because of the large enthalpy change (Δ<em>H</em>) at room temperature (RT), whose properties are determined by the ordering arrangement of two kinds of heterovalent ions in B-sites. This work continuously adjusts the ordering degree (<em>Ω</em>)<em> </em>for PST ceramics in a large scale from 0.51 to 1 by multiple heat treatment processes. For the PST sample with <em>Ω </em>= 1, a large Δ<em>H</em> = 1.06 J g<sup>-1</sup> and a huge EC Δ<em>T</em><sub>max </sub>= 4.26 K (@60 kVcm<sup>-1</sup>) are obtained due to the highly ordered arrangement of Sc<sup>3+</sup> and Ta<sup>5+</sup> ions. With the reduction of <em>Ω</em>, the Curie temperature gradually shifts from RT to below 0 °C, and the phase transition is diffused. A fairly large Δ<em>T</em><sub>max </sub>= 1.57 K is obtained at a rather low temperature of 0 °C in the ceramic with <em>Ω </em>= 0.51. This work proves that lattice ordering is another efficient route to modify ferroelectric features, and the achieved large Δ<em>T</em><sub>max</sub> in a wide temperature range near/below RT facilitates high-performance cooling devices a cascade design towards the most urgent market needs.