Saha Dipankar, Sławiński Wojciech A, Kumar Susmit, Fjellvåg Helmer
Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway.
Faculty of Chemistry, University of Warsaw, Ludwika Pasteura 1, 02-093 Warsaw, Poland.
Inorg Chem. 2024 Aug 19;63(33):15503-15509. doi: 10.1021/acs.inorgchem.4c02667. Epub 2024 Aug 8.
MnAs is an interesting material due to its magnetocaloric properties, which can be utilized in magnetic refrigeration. However, despite major efforts, its magnetic refrigeration performances in the substituted forms could not be improved compared to the parent MnAs phase. Both small and big box modeling of the pair distribution function of MnAs for the local structure description and powder X-ray diffraction for the average structure reveal an inherent local orthorhombic distortion in the hexagonal structure of MnAs. As a result of this distortion, any modification to the hexagonal structure results in an orthorhombic structure and a weaker magnetocaloric performance. This study highlights the importance of studying local distortion in magnetic materials. This is achieved by combining X-ray absorption spectroscopy with total scattering X-ray diffraction.
MnAs因其磁热性质而成为一种有趣的材料，可用于磁制冷。然而，尽管付出了巨大努力，与原始MnAs相相比，其替代形式的磁制冷性能并未得到改善。用于局部结构描述的MnAs对分布函数的小盒和大盒建模以及用于平均结构的粉末X射线衍射均揭示了MnAs六方结构中固有的局部正交畸变。由于这种畸变，对六方结构的任何修改都会导致正交结构和较弱的磁热性能。本研究强调了研究磁性材料局部畸变的重要性。这是通过将X射线吸收光谱与全散射X射线衍射相结合来实现的。
