反铁电体中的热释电效应和电卡效应研究

项目名称： 反铁电体中的热释电效应和电卡效应研究

项目编号： No.10874130

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 杨同青

作者单位： 同济大学

项目金额： 35万元

中文摘要： 具有大的热释电效应和电卡效应一直是铁电材料在热释电红外探测器和致冷器应用上所追寻的目标。反铁电体由于结构上相邻子晶格自发极化方向的反向平行排列，可在电场诱导下发生反铁电与铁电的相互转变，呈现较高的极化强度和介电常数的非线性变化。本项目采用固相反应法制备了PZST反铁电陶瓷，研究了FE-AFE相界附近组份变化对场诱相变所导致的极化强度、介电常数、相变临界参数等的影响；通过A位离子调控，将反铁电体的居里温度从高温调整到室温附近。通过电场的诱导，在PZST反铁电体中获得了本征和介电辐射热计两种热释电响应。本征热释电峰值系数达到300×-8℃cm2K数量级，呈现较宽的移动范围。反铁电体的介电常数在居里温度附近呈现出较高的电场可调性能，而介电辐射热计热释电响应依赖于介电常数偏置电场下的变化率，随着偏置电场的增大而增大，具有可调性。通过对铁电体、反铁电体电卡效应的直接测试，获得了与电滞回线(P-E)相对应的电卡回线(T-E)，温度的变化与极化强度相对应，有非线性和线性变化区域。研究发现电卡效应的大小与材料组份和居里温度，以及诱导电场的大小和激励模式、测试温度等密切相关。首次观察到逆电卡效应。

中文关键词： 反铁电体；场诱相变；热释电效应；电卡效应；电场诱导

英文摘要： Ferroelectric materials with high pyroelectric effect and electrocaloric effect are expected at all times for applications of pyroelectric infrared detector and refrigerator. Antiferroelectricity don't display macroscopic polarization due to its special sub-lattice structure. Upon application of an electric field to the antiferroelectric ceramics, the ferroelectric phase can be induced from antiferroelctric phase. This phase transition is accompanied by a nonlinear change in physical properties, such as an abrupt jump in polarization and dielectric constant. Therefore, utilizing the nonlinear properties of polarization of antiferroelectric materials induced by the external fields of electric-field or temperature, high pyroelectric effect and electrocaloric effect of antiferroelectricity are expected to come true. Hence, in this project, the nonlinear change of polarization with the external fields is the key point. In order to realize the aim, PZST antiferroelectric ceramics were prepared by solid-state reaction method and modified in A site, and the properties of field-induced phase transition were studied in detail. The peak pyroelectric response is about 300×-8℃cm2K, which can be ajusted by electric field,and dielectric bolometer reponse was observed at Tc. By measurement, the T-E hysteresis loop of electrocaloric effect was observed, with linear and nonlinear change. The effect of Tc,temperature, mode of appled electric field and composition on electrocaloric effect was also studied. Inverse electrocaloric effect was observed firstly.

英文关键词： antiferroelectricity; field-induced phase transition; pyroelectric effect; electrocaloric effect; electric field induced