铁电体热释电循环的能量转换机理  

Mechanism of energy conversion of ferroelectric in pyroelectric cycle

作　　者：曹万强[1] 沈孟 张清风[1] 陈勇 郭全胜[1] Wanqiang Cao;Meng Shen;Qingfeng Zhang;Yong Chen;Quansheng Guo(Key Laboratory of Ministry of Education for the Green Preparation and Application of Functional Materials,Key Laboratory of Ferro&Piezoelectric Materials and Devices of Hubei Province,Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials,School of Materials Science and Engineering,Hubei University,Wuhan 430062,China;School of Physics and Electronic Science,Hubei University,Wuhan 430062,China)

机构地区：[1]湖北大学材料科学与工程学院,有机化工新材料湖北省协同创新中心,铁电压电材料与器件湖北省重点实验室,功能材料绿色制备与应用教育部重点实验室,武汉430062 [2]湖北大学物理与电子科学学院,武汉430062

出　　处：《科学通报》2023年第8期972-980,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(51872079)资助。

摘　　要：环境中的废热可以被铁电体在变温和变电场的热释电循环中转换为电能.然而,铁电体的极化强度随外界条件的变化一直是待解的难题.本文根据电场作用下铁电体中偶极子在三维空间转动的唯象理论,引入偶极子的耦合效应解决了极化强度在一定初始条件下随温度和电场的变化规律,推导出了奥尔森热释电循环中温度和电场对极化强度和热释电转换效率的影响规律.通过数值模拟得到如下结论:热释电循环的等高温线与电滞回线的上曲线重合;等低温线在电滞回线的中线与上线之间,由所加最大电场决定;热释电循环时,低温端的温度越接近居里点,以及高温端的温度略高于居里点,会有较高且较为稳定的热释电转换效率.上述结论与实验结果基本相符.“Waste heat”in the environment can be converted into electric energy by the Seebeck effect of semiconductor and pyroelectric effect of ferroelectrics ascribed to induction effect of polarization by electric field applied,energy conversion originates from the difference of polarization hysteresis electric field(P-E)loops between two different temperatures.Two isothermal processes and two iso-electric field processes form a pyroelectric cycle.By absorbing and releasing heat between two thermal reservoirs,a ferroelectric change its polarization successively so as to convert heat into electricity in a thermal-electric cycle,similar to the Carnot cycle.Output electric energy is the area enclosed by the cycle.For a constant high temperature environment,how to design a ferroelectric with proper Curie temperature and how to set cycling condition to match the temperatures to enlarge the area of a cycle are the two crucial problems.Experiment researches on pyroelectric energy conversion have been performed since the 1960s.The theoretic research was limited on simple expressions due to the difficulty on solving P-E loop.The P-E loop of ferroelectrics stems from rotation of dipoles and polarization hysteresis.In three-dimensional ferroelectrics,Gibbs free energies in the orientation directions of dipoles change with applied electric field differently,which causes changes in probabilities of dipole in different directions,i.e.,rotation effect of dipoles.By introducing a coupling factor in the parallel dipoles the hysteresis effect was solved.The above solutions are extended to pyroelectric cycle to solve the problems referring to two isothermal processes and two iso-electric field processes with different initial condition.By combining the rotation effect and coupling effect that the coupling strength between dipoles is proportional to the rotated dipoles in the field direction during the field increasing process and persists to the same value in the field withdrawing process,mechanisms of polarization hysteresis are deri

关 键 词：铁电体 能量转换 热释电循环 极化强度 热释电 

分 类 号：TM221[一般工业技术—材料科学与工程]