Jeon Hyunsoo, Wang Chongze, Yi Seho, Cho Jun-Hyung
Department of Physics, Research Institute for Natural Science, and Institute for High Pressure at Hanyang University, Hanyang University, 222 Wangsimni-ro, Seongdong-ku, Seoul, 04763 Republic of Korea.
Sci Rep. 2020 Oct 9;10(1):16878. doi: 10.1038/s41598-020-73665-1.
The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high-[Formula: see text] superconductivity at high pressure. Recently, cerium hydride [Formula: see text] 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 [Formula: see text] and [Formula: see text]. 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 [Formula: see text].
具有笼形结构的稀土金属氢化物因其在高压下有望实现高[化学式：见原文]超导性而备受关注。最近，与其他实验合成的稀土氢化物（如[化学式：见原文]和[化学式：见原文]）相比，由包裹铈的笼形氢笼组成的氢化铈[化学式：见原文]在80 - 100 GPa的低得多的压力下合成。基于密度泛函理论计算，我们发现Ce的5p半芯态和4f/5d价态与H的1s态强烈杂化，同时发生从Ce到H原子的电子转移。此外，我们揭示Ce 4f电子的离域性质在笼形氢笼的化学预压缩中起重要作用。我们的发现不仅表明Ce原子与氢笼之间的键合性质为离子键和共价键的混合，而且对于理解导致合成[化学式：见原文]所需压力降低的增强化学预压缩的起源具有重要意义。
