Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, School of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006, China.
Institute for Advanced Materials and Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou, 510006, China.
Sci Rep. 2017 Mar 27;7:45335. doi: 10.1038/srep45335.
Both relaxor ferroelectric and antiferroelectric materials can individually demonstrate large electrocaloric effects (ECE). However, in order to further enhance the ECE it is crucial to find a material system, which can exhibit simultaneously both relaxor ferroelectric and antiferroelectric properties, or easily convert from one into another in terms of the compositional tailoring. Here we report on a system, in which the structure can readily change from antiferroelectric into relaxor ferroelectric and vice versa. To this end relaxor ferroelectric PbLa(ZrTi)O and antiferroelectric PbLa(ZrTi)O ceramics were designed near the antiferroelectric-ferroelectric phase boundary line in the LaO-PbZrO-PbTiO phase diagram. Conventional solid state reaction processing was used to prepare the two compositions. The ECE properties were deduced from Maxwell relations and Landau-Ginzburg-Devonshire (LGD) phenomenological theory, respectively, and also directly controlled by a computer and measured by thermometry. Large electrocaloric efficiencies were obtained and comparable with the results calculated via the phenomenological theory. Results show great potential in achieving large cooling power as refrigerants.
弛豫铁电体和反铁电体材料各自都可以表现出较大的电卡效应（ECE）。然而，为了进一步提高 ECE，关键是要找到一种材料体系，它可以同时表现出弛豫铁电体和反铁电体的特性，或者可以通过组成调整很容易地从一种特性转换为另一种特性。在这里，我们报告了一个系统，其中结构可以很容易地从反铁电体转变为弛豫铁电体，反之亦然。为此，我们在 LaO-PbZrO-PbTiO 相图中的反铁电-铁电相界附近设计了弛豫铁电 PbLa(ZrTi)O 和反铁电 PbLa(ZrTi)O 陶瓷。采用传统的固态反应法制备了这两种成分。ECE 特性分别通过麦克斯韦关系和朗道-金兹堡-德文希尔（LGD）唯象理论推断得出，也可以通过计算机直接控制和温度测量进行直接测量。获得了较大的电卡效率，与唯象理论计算的结果相当。结果表明，作为制冷剂，在获得较大制冷功率方面具有很大的潜力。
