Electrocaloric solid-state refrigeration is a primary candidate for the next-generation cooling method for microelectronic systems. However, the mechanisms of electrocaloric effect remain unclear due to the lack of direct correlation evidence, especially for novel negative electrocaloric (NEC) effect. In this work, we develop a high-accuracy direct measurement method for simultaneously measuring local electrocaloric and electrostrain responses under ambient conditions, providing the accompanying electrostrain evidence during electrocaloric effect. Combined with experiments, thermodynamic analyses and finite element simulations, it is found that the electrostrain is very large when NEC and large positive electrocaloric (PEC) responses occur, and NEC effect is caused by ferroelectric-ferroelectric phase transition, while large PEC response originates from paraelectric-ferroelectric phase transition. Results also indicate that NEC temperature change does not increase with electric field, and shows the maximum temperature change at phase transition critical electric field, different from PEC temperature change increasing with electric field. The developed method provides an alternative and sensitive pathway to investigating electrocaloric effect.

中文翻译：

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通过同时直接测量环境条件下的局部电热和静电应变来揭示电热效应的机制


电热固态制冷是下一代微电子系统冷却方法的主要候选者。然而，由于缺乏直接相关证据，电热效应的机制仍不清楚，特别是新型负电热（NEC）效应。在这项工作中，我们开发了一种高精度直接测量方法，用于同时测量环境条件下的局部电热和电应变响应，在电热效应期间提供伴随的电应变证据。结合实验、热力学分析和有限元模拟发现，当发生NEC和大的正电热（PEC）响应时，静电应变非常大，NEC效应是由铁电-铁电相变引起的，而大PEC响应源于铁电-铁电相变。顺电-铁电相变。结果还表明，NEC 温度变化不随电场增加而增加，并且在相变临界电场处表现出最大温度变化，这与 PEC 温度变化随电场增加不同。所开发的方法为研究电热效应提供了一种替代且灵敏的途径。