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
作者
曹万强
沈孟
张清风
陈勇
郭全胜
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)
出处
《科学通报》
EI
CAS
CSCD
北大核心
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。
关键词
铁电体
能量转换
热释电循环
极化强度
热释电
ferroelectrics
energy conversion
pyroelectric cycle
polarization
pyroelectric
