High-Pressure Polymorphs of LaHO with Anion Coordination Reversal
High-Pressure Polymorphs of LaHO with Anion Coordination Reversal
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DOI：
10.1021/jacs.9b03320
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发表时间：
2019-06-05
影响因子：
15
通讯作者：
Kageyama, Hiroshi
中科院分区：
文献类型：
--
作者：
Broux, Thibault;Ubukata, Hiroki;Kageyama, Hiroshi
成功地预测了两种新的高压晶型氧化镧，并在加压下实现了稳定。当反应压力为3 Gpa时，LaHO具有阴离子中心四面体(HLa4/OLa4)构型的萤石结构转变为PbCl2结构，H-的配位数增加到五个(HLa5方形金字塔)。进一步加压至5 GPa时，Laho转变为反Fe2P型结构。有趣的是，5 GPA相包含四面体HLa4和方形金字塔OLa5几何结构，这意味着配位开关，通过从头计算证实。结构分析表明，这种前所未有的现象是由于氢化物阴离子具有较高的可压缩性，并强调了它在寻找新的氢化物基混合阴离子材料高压形式方面的潜力。
Two novel high-pressure polymorphs of lanthanum oxyhydride have been successfully predicted and stabilized under pressure. When reacted at 3 GPa, the fluorite structure of LaHO with anion-centered tetrahedral (HLa4/OLa4) geometry is transformed to the PbCl2-type structure involving coordination number increase of H- to five (HLa5 square pyramids). Upon further application of pressure to 5 GPa, LaHO changed into the anti Fe2P-type structure. Interestingly, the 5 GPa phase contains tetrahedral HLa4 and square-pyramidal OLa5 geometry, meaning coordination switching, as confirmed by ab initio calculations. The structural analysis shows that this unprecedented phenomenon is enabled by higher compressibility of hydride anion and emphasizes its potential in the search for new high-pressure forms of hydride-based mixed anion materials.