Phonon anomalies and structural instabilities in TbScO3 (SXD)

Distorted perovskite TbScO3 is a particularly interesting lanthanide scandate, exhibiting a dramatic flexoelectric effect, along with the common features of the wider family of lanthanide scandates. Accurate knowledge of its structure and dynamics is of particular importance, for example due to its use as a substrate for epitaxial growth of high-quality perovskite thin films. However, the structure and dynamics of this material at low temperatures are not properly understood. We plan to investigate these by combining phonon studies with powder and single crystal neutron diffraction. Powder diffraction on HRPD and single crystal diffraction on SXD will be used to study structural models and characterise subtle distortions of this material. Phonon spectrometry on MERLIN – preceded by careful phonon characterization using CASTEP with Horace and the Euphonic package – will be used to clarify discrepancies between phonon modes allowed by symmetry and those previously experimentally observed.

畸变钙钛矿型铽酸钪（TbScO3）是一类极具研究价值的镧系钪酸盐，除具备该材料家族共有的典型特征外，还展现出显著的挠曲电效应（flexoelectric effect）。精准掌握其结构与动力学特性具有重要意义，例如它可作为高质量钙钛矿薄膜外延生长的衬底材料。然而，目前学界对该材料在低温条件下的结构与动力学行为尚未形成充分认知。本研究拟结合声子（phonon）研究与粉末、单晶中子衍射技术开展相关探究：其中，采用HRPD开展粉末衍射实验、利用SXD开展单晶衍射实验，用于构建该材料的结构模型并表征其细微晶格畸变；随后，借助MERLIN中子谱仪开展声子光谱测量——在此之前，将通过CASTEP软件结合Horace与Euphonic工具包完成细致的声子特性表征，以厘清对称性允许的声子模式与既往实验观测结果间存在的分歧。