A direct insight into ferroelectricty under pressure by X-ray absorption spectroscopy

The overarching aim of this project is to re-examine the general issue of breaking of inversion symmetry at extreme pressures. We focus here on the model ferroelectric perovskite PbTiO3. The approach is to use X-ray absorption spectroscopy to probe the local environment of the Pb and Ti cations and look for direct proofs of off-centring at high pressures. Measurements will be carried out up to 100 GPa, at room temperature and at 15 K for a more relevant comparison with first-principle calculations. Together with our recent infrared spectroscopy data, this is expected to provide new insight on the reality of ferroelectricty under pressure.

本项目的核心目标是重新审视极端压力下反演对称性破缺这一普适性问题。本研究聚焦于模型铁电钙钛矿（ferroelectric perovskite）钛酸铅（PbTiO3）。研究方案采用X射线吸收光谱（X-ray absorption spectroscopy）探测铅（Pb）与钛（Ti）阳离子的局域环境，以探寻高压下原子中心位移的直接证据。实验测量将在高达100吉帕斯卡（GPa）的压力条件下开展，分别设置室温与15 K两个测试温度，以便与第一性原理计算（first-principle calculations）进行更具相关性的比对。结合我们近期获取的红外光谱数据，本研究有望为压力条件下铁电性的存在性提供全新的认知视角。