文章基本信息

标题：Origin of enhanced chemical precompression in cerium hydride $$\hbox {CeH}_{{9}}$$ CeH 9
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作者：Hyunsoo Jeon ; Chongze Wang ; Seho Yi 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2020
卷号：10
期号：1
页码：1-6
DOI：10.1038/s41598-020-73665-1
出版社：Springer Nature
摘要：The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high- $$T_{\rm{c}}$$ superconductivity at high pressure. Recently, cerium hydride $$\hbox {CeH}_9$$ composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80–100 GPa, compared to other experimentally synthesized rare-earth hydrides such as $$\hbox {LaH}_{{10}}$$ and $$\hbox {YH}_6$$ . Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of $$\hbox {CeH}_9$$ .
其他摘要：Abstract The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high- $$T_{\rm{c}}$$ T c superconductivity at high pressure. Recently, cerium hydride $$\hbox {CeH}_9$$ CeH 9 composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80–100 GPa, compared to other experimentally synthesized rare-earth hydrides such as $$\hbox {LaH}_{{10}}$$ LaH 10 and $$\hbox {YH}_6$$ YH 6 . Based on density-functional theory calculations, we find that the Ce 5 p semicore and 4 f /5 d valence states strongly hybridize with the H 1 s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4 f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of $$\hbox {CeH}_9$$ CeH 9 .