高灵敏度、宽温区反铁电基场致热释电材料的研究

Pyroelectric material was an important part of uncooled infrared detection equipments, and its performance directly determined the detection   ability of the detector.Lead lanthanum zirconium titanium stannate (PLZST) based antiferroelectric material was seen as one of the important alternative materials used in infrared detectors with high properties because of its dc field–induced dielectric enhancement effect.In order to solve the bad pyroelectric properties, high curie temperature and narrow temperature zone of PLZST based antiferroelectric ceramic used as sensitive element of infrared detectors, a co-precipitation method with buffer solution was used to prepare PLZST based antiferroelectric powder with good purity and accurate chemical composition in this project so as to improve the pyroelectric propertie. Partial Pb was substituted by Ba to decrease the curie temperature of antiferroelectric ceramics and at the same time, Mn replacing Ti was used to increase the stability of antiferroelectric phase,improve the field-induced dielectric enhancement effect and the pyroelectric properties of antiferroelectric ceramics. By forming antiferroelectric particles with different curie temperature encapsulated by PbO-B2O3 glass phase structure to stop the interdiffusion among different antiferroelectric phase, antiferroelectric composite ceramic with coexistent multi-phase was successfully fabricated. Through the superposition of the pyroelectric effect for each composition,the pyroelectric properties of the composite ceramic was enhanced and the using temperature zone was widened.

热释电材料作为非制冷红外探测设备的重要组成部分，其性能直接决定了探测器的探测能力。锆钛锡酸铅镧（PLZST）基反铁电体具有优良的场致介电增强效应，被看作是用来制备高性能红外探测器的重要备选材料之一。本项目基于解决目前PLZST基反铁电陶瓷用于红外探测器敏感元材料存在的热释电性能不够好、居里温度偏高及使用温区过窄等问题，拟采用缓冲液共沉淀法制备纯度高且化学组成控制准确的PLZST基反铁电粉体，提高陶瓷场致热释电性能；利用Ba部分取代Pb降低反铁电陶瓷居里温度的同时，通过Mn部分取代Ti以增强反铁电相的稳定性，提高陶瓷的场致介电增强效应和热释电性能；通过形成PbO-B2O3玻璃对几种居里温度不同的反铁电粉体的包裹结构以阻止反铁电相间的直接扩散，获得多相共存复相体系；利用各组分热释电效应的叠加，实现反铁电复相陶瓷热释电性能的提高和使用温区的展宽。

热释电材料作为非制冷红外探测器的重要组成部分，其性能直接决定了探测器的探测能力。(Pb,La)(Zr,Sn,Ti)O3基反铁电体具有优良的场致介电增强效应，被看作是用来制备高性能红外探测器的重要备选材料之一。本项目针对目前(Pb,La)(Zr,Sn,Ti)O3基反铁电陶瓷用作场致热释电材料遇到的热释电性能偏低、居里点太高，使用温区过窄等问题开展了一系列相关的研究。利用溶胶凝胶法，我们制备出了粒径约为200nm，且尺寸均一的反铁电纳米粉，并将其在1100℃的低温下烧结成了陶瓷。实验结果显示，采用溶胶凝胶法制备的反铁电陶瓷可以有效避免Sn元素偏析现象，从而展现出更纯的钙钛矿相和更优的铁电及热释电特性。通过利用具有惰性气体型外层电子云结构的Ba2+对Pb(Zr,Sn,Ti)O3中具有非惰性气体型外层电子云结构的Pb2+的取代有效降低了反铁电陶瓷的居里温度，并同时利用Mn离子取代Ti离子大幅提高了反铁电陶瓷在室温下的热释电性能。采用低熔点的PbO-B2O3玻璃作为助烧剂，通过研究玻璃的添加量、烧结时间及不同氧化铅含量的玻璃对反铁电陶瓷的微观结构、介电、铁电及场致效应的影响，揭示了反铁电陶瓷的介电及场致热释电性能与结构和晶相控制间的关系，最终实现了具有良好热释电性能的反铁电陶瓷在1000℃的烧结。基于热处理的粉料活性比较低，不易发生反应的原理，通过将两种不同居里点的反铁电粉料预处理后相混合，制备出了具有双热释电峰的反铁电复相陶瓷，从而大幅拓展了热释电高灵敏度的温区。项目的实施对促进我国热释电红外探测器研究、开发和应用水平的提高具有重要的推动作用。此外，在本项目支持下，项目组还开展了0.94Bi0.5Na0.5TiO3-0.06BaTi0.8Zr0.2O3无铅陶瓷热释电特性和(Pb,La)(Zr,Sn,Ti)O3基反铁电材料储能特性的研究，并研制出了高性能的无铅热释电材料和反铁电基储能材料。