Nguyen Loi T, Cava R J
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Chem Rev. 2021 Mar 10;121(5):2935-2965. doi: 10.1021/acs.chemrev.0c00622. Epub 2020 Sep 21.
Hexagonal perovskites, in contrast to the more familiar perovskites, when oxides, allow for face-sharing of metal-oxygen octahedra or trigonal prisms within their structural frameworks. This results in dimers, trimers, tetramers, or longer fragments of chains of face-sharing octahedra in the crystal structures, and consequently in much shorter metal-metal distances and lower metal-oxygen-metal bond angles than are seen in the more familiar perovskites. The presence of the face-sharing octahedra can have a dramatic impact on magnetic properties of these compounds, and dimer-based materials, in particular, have been the subjects of many quantum-materials-directed studies in materials physics. Hexagonal oxide perovskites are also of contemporary interest due to their potential for geometrical frustration of the ordering of magnetic moments or orbital occupancies at low temperatures, which is especially relevant to their significance as quantum materials. As such, several hexagonal oxide perovskites have been identified as potential candidates for hosting the quantum-spin-liquid state at low temperatures. In our view, hexagonal oxide perovskites are fertile ground for finding new quantum materials. This review briefly describes the solid state chemistry of many of these materials.
与更为常见的钙钛矿不同，六方钙钛矿在作为氧化物时，其结构框架内允许金属 - 氧八面体或三角棱柱进行面共享。这导致晶体结构中出现面共享八面体链的二聚体、三聚体、四聚体或更长片段，因此与更为常见的钙钛矿相比，金属 - 金属距离更短，金属 - 氧 - 金属键角更小。面共享八面体的存在会对这些化合物的磁性产生显著影响，特别是基于二聚体的材料，一直是材料物理学中许多量子材料导向研究的主题。六方氧化物钙钛矿在当代也备受关注，因为它们在低温下可能使磁矩或轨道占据的有序排列产生几何阻挫，这与其作为量子材料的重要性尤其相关。因此，几种六方氧化物钙钛矿已被确定为低温下承载量子自旋液体态的潜在候选材料。在我们看来，六方氧化物钙钛矿是寻找新型量子材料的沃土。本综述简要描述了其中许多材料的固态化学。
