短周期钙钛矿铁电超晶格压电效应机理研究

Perovskite ferroelectric superlattice is currently hot topic of ferroelectric material research field.By changing the epitaxial strain and component to control the superlattice properties is one of the important ways to design and develop high performance ferroelectric materials. Recent investigation reports that superlattices containing polar discontinuities have large nonswitchable polarization ,which may induce a robust temprature-independent piezoelectric response like PZT.The project will use these superlattices as the research objects, combined with the first-principles calculation and experimental methods, and focuses on the study of ferroelectric and piezoelectric behaviour in the superlattices containing polar discontinuities from the electronic and atomic level. In order to reveal the inherent mechanism of piezoelectric behaviour and establish properties evaluation method of polarity discontinuities piezoelectric superlattice, the effect of polar discontinuities, component and strain on the properties of superlattices is analysized and change rules of superlattice properties under the condition of different components and strains are explored. The project aims at achieving the breakthrough in the piezoelectric behaviour research of superlattices containing polar discontinuities and obtaining some new scientific laws and phenomena, and providing scientific basis for deeply understanding piezoelectric behaviour of ferroelectric superlattices and designing a new type of piezoelectric materials.

钙钛矿铁电超晶格研究是目前铁电材料领域的研究热点，通过改变外延应变和组分来控制超晶格性能是设计和研制高性能铁电材料的重要途径之一。最近研究报道极性不连续超晶格具有不可变化极化特性，并可能会诱发象PZT那样对温度不敏感的压电行为。本项目以这类新型超晶格为研究对象，结合第一性原理计算和实验方法，从电子和原子层次上重点研究极性不连续超晶格的铁电压电行为，分析极性不连续、组分以及应变对超晶格性能的影响，探索在不同组分和应变条件下极性不连续超晶格性能变化规律，揭示压电效应内在机理，建立极性不连续压电超晶格性能评价方法。目标是在极性不连续铁电超晶格压电行为研究等方面有所突破，获得一些新的科学规律和现象，为深入理解铁电超晶格压电行为、设计新型压电材料等方面提供科学依据。

本项目通过第一性原理计算研究了极性不连续钙钛矿铁电超晶格PbTiO3/KTaO3、BiAlO3/PbTiO3、PbTiO3/LaAlO3和PbTiO3/KNbO3 在不同组分和不同应变条件下的电子结构、原子结构、极化和压电行为,探索了组分、应变与结构性能之间的关系，探索了界面电荷对性能的影响规律。研究结果为深入理解铁电超晶格极化压电行为、设计新型压电材料等方面提供科学依据。研究了Pb基钙钛矿铁电超晶格（PbTiO3/KNbO3、PbTiO3/LaAlO3和PbTiO3/KTaO3）和无铅钙钛矿铁电超晶格（BaTiO3/SrTiO3、KNbO3/KTaO3和BaTiO3/KNbO3）中正离子对极化压电贡献，建立了一个研究铁电超晶格中A、B位原子对整体的极化和压电贡献的理论计算和分析方法。