Extremely Shallow Valence Band in Lanthanum Trihydride
Extremely Shallow Valence Band in Lanthanum Trihydride
复制标题
三氢化镧的极浅价带
DOI：
10.1021/jacs.2c10927
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发表时间：
2023
影响因子：
15
通讯作者：
Hideo Hosono
中科院分区：
文献类型：
--
作者：
Tomoyuki Yamasaki;Soshi Iimura;Junghwan Kim;Hideo Hosono
溶剂中的氢化物离子（H -）是一种化学活性强的阴离子，具有很强的给电子能力，在有机化学中用作还原剂。本文通过光发射（紫外光电子和光电子产额谱）测量和密度泛函理论计算，评价了固体镧氢化物laxx（2≤x≤3）中h - 1s电子的能级。我们发现，在lah3中获得了一个非常浅的价带最大值，电离电位为3.8 eV，主要原因是氢的电负性小，相邻H-s之间的键-反键相互作用明显，与h填充萤石相关结构的紧密分离有关。这些结果鼓励了对氢化物半导体中p型传导的挑战，并为多氢化物超导体的化学理解提供了线索。
Hydride ions (H–) in solvents are chemically active anions with strong electron-donating ability and are used as reducing agents in organic chemistry. Here, we evaluate the energy level of 1s-electrons in H–accommodated in solid lanthanum hydrides, LaHx(2 ≤x≤ 3), by photoemission (ultraviolet photoelectron and photoelectron yield spectroscopies) measurements and density functional theory calculations. We show that a very shallow valance band maximum with an ionization potential of 3.8 eV is attained in LaH3and that the primary cause is attributed to the small electronegativity of hydrogen and the significant bonding–antibonding interaction between neighboring H–s with a close separation originating from the H-stuffed fluorite-related structure. These results encourage the challenge for p-type conduction in hydride semiconductors and provide a clue to the chemical understanding of polyhydride superconductors.