BiFeO3-BaTiO3压电陶瓷的A位空位构筑及其性能调控机制研究

BFO-BT压电陶瓷因同时具有高居里温度、较高压电系数和无铅化特点，是极具应用前景的无铅高温压电陶瓷材料。目前电致应变低及高温电导大是该材料用于高温驱动器应用时需要解决的关键难题。本项目将以MPB区域的BFO-BT压电陶瓷为研究对象，从材料铁电性物理起源、电致应变及电导机制等相关物理本质出发，在BFO-BT材料中构筑A位空位点缺陷，通过改变BFO-BT材料局域结构及化学计量比等调控电致应变及电导特性；研究不同组成及热处理工艺对材料性能影响规律；研究外场下相结构演变及载流子响应行为，揭示BFO-BT材料电致应变及高温电导机制，建立微观结构和宏观性能的内在联系，发展出获得高电致应变、低电导及优异温度稳定性BFO-BT材料新方法。本项目的实施可深入理解MPB附近BFO-BT基材料的结构-性能本质关联，相关物理机制同时可以拓展到其它Bi基压电材料中，为设计高性能无铅压电新材料提供指导。

BiFeO3-BaTiO3 (BFO-BT) piezoelectric ceramics possess high Curie temperatures, high piezoelectric coefficients and lead-free, making them the most promising lead-free high-temperature piezoelectric ceramics. Currently there exist two key problems including low electrostrain and high temperature conductivity of BFBT, which need to be solved before being used in high temperature actuators. BFO-BT piezoelectric ceramics near the morphotropic phase boundary (MPB) are chosen as the research object. This project will begin with the physical origins of ferroelectrics, electrostrain and conductivity, by designing A-site vacancy of BFO-BT materials to change local stucture and stoichiometric ratio, adjusting electrostrain andconductivity characteristics. The influence of different compositions and heat treatment processes on material properties, the phase structure evolution, ferroelectric domain and carrier response behaviors under external field will be studied, to reveal the mechanism of electrostrain and high temperature conductivity for BFO-BT, establishing the intrinsic relationship between microstructure and macroscopic properties, and developing a new method for preparing BFO-BT materials with high electrostrain, low conductivity and excellent temperature stability. This project will promote the understanding about the structure-performance relationships of BFO-BT-based materials near MPB, and the related physical mechanisms can be extended to other Bi-based piezoelectric materials, providing guidance for designing new high-performance lead-free high temperature piezoelectric materials.