稀土增强反铁电薄膜取向生长及场诱导相变储能研究

Antiferroelectric materials are very important for applications in pulse power technology due to super energy storage properties. Larger phase transition electric field from antiferroelectric to ferroelectric (E(AFE-FE) ) and enhanced energy storage properties can be obtained in rare earth elements doped PbZrO3 antiferroelectric(RE-AFE). Antiferroelectric thin films become hot research field in energy storage dielectric materials due to oriented growth and improved break down electric field, which makes the pulse capacitor become smaller. Orientation growth and electric field induced energy storage is base for application of antiferroelectric thin films for pulse capacitor. In this project, RE-AFE with high E(AFE-FE) are selected as the research objective. RE-AFE thin films will prepared by sol-gel and sputtering process. The effects of thermal annealing, substrates, buffer layers on orientation growth will be investigated. The effects of substrates, buffer layers and electrode interfaces on energy storage properties of RE-AFE thin films will be studied. The charge-discharge properties of RE-AFE thin films will be investigated. The mechanism of buffer layer affecting microstructure and orientation growth will be obtained. The effect of microstructure, orientation and interface on energy storage properties and charge-discharge properties will be explained. This project will provide knowledge for pulse power technology of our country, and enrich research content of dielectric physics.

反铁电介质材料由于具有高储能密度，在脉冲功率技术中具有重要应用。稀土元素部分取代锆酸铅反铁电介质中的铅或锆均可提高反铁电-铁电相变电场，显著提高储能密度。薄膜型反铁电介质可以实现取向生长，耐击穿场强增大，有望大幅度减小脉冲储能电容器体积，成为储能介质的研究热点。稀土增强反铁电薄膜的取向生长及场诱导相变储能研究是其电容器应用的基础。本项目选取高反铁电-铁电相变电场的稀土增强锆酸铅反铁电薄膜为对象，采用溶胶-凝胶法和磁控溅射法制备稀土增强反铁电薄膜，研究热处理工艺、衬底、缓冲层对取向生长的影响；研究衬底、缓冲层以及电极界面对稀土增强反铁电薄膜的储能特性的影响；研究不同取向的稀土增强反铁电薄膜的动态放电特性。揭示缓冲层对稀土增强反铁电薄膜的微观结构及取向生长的影响机制；阐明微结构、取向、界面影响稀土增强反铁电薄膜储能及动态放电特性的规律，为我国脉冲功率技术提供知识积累，丰富电介质物理研究内涵。

反铁电介质材料由于具有高储能密度，在脉冲功率技术中具有重要应用。反铁电薄膜材料耐击穿场强高，能大幅缩减脉冲储能电容器体积，是储能介质研究热点，关于取向生长及场诱导相变储能特性的研究是其电容器应用的基础。本项目围绕高反铁电-铁电相变电场的稀土增强锆酸铅反铁电薄膜的研制和探索，首先解决了平整光滑LaNiO3缓冲层的生长问题，掌握了单晶衬底酸腐蚀暴露单一原子终止层和含铅反铁电薄膜退火工艺方法；制备了一系列Pb1−3x/2LaxZrO3 (x=0~0.12)反铁电薄膜，(111)取向大于97.1%，通过在A位引入化学压提高转折电场，优化储能特性（23.5 J/cm3、72%），化学压引入增大了AFE-FE相变势垒，反铁电性增强，同时La引入减弱了AFE-FE电致应变，获得疲劳特性优异的反铁电薄膜（1×108次循环保持稳定）；不同厚度薄膜中存在同质界面，随膜厚增加同质界面增多，出现大周期非公度调制结构使转折电场减小，反铁电性减弱；在Nb:SrTiO3衬底上制备(100)、(110)和(111)薄膜分别具有96.1%、97.2%和99.0%取向度，不同取向薄膜转折电场的差异与极化和外加电场夹角及电场在极化方向上的分量大小相关；为了进一步增强击穿强度，设计了一种TiO2纳米线阵列/反铁电复合薄膜新结构，显著提升击穿强度（1560提升至2230 kV/cm），降低了高温和低温下漏电流，获得了较高储能密度（50.6 J/cm3）和优异-120~130 ºC宽温稳定性（变化率均小于5%）；首次制备出B位复合离子Pb(Yb0.5Nb0.5)O3钙钛矿反铁电薄膜，报道了PYN体系室温下的宏观反铁电行为，探索出PYN薄膜生长机理，实现了B位离子的有序排列；揭示了铅基反铁电体系中大小和角度两类极化调制模式的结构本质；探索了稀土La对无铅反铁电AgNbO3和NaNbO3体系反铁电性和储能特性的增强效应；对比分析了反铁电电容器储能特性的电滞回线积分法、UI积分法、电阻能量消耗法和等效参数评估方法。以上研究结果揭示了微观结构和取向生长对稀土增强反铁电薄膜场诱导相变行为的影响机制，阐明了稀土增强反铁电薄膜的储能特性及充放电性能的变化规律，为我国脉冲功率技术提供了一定的知识积累。