Atomic and electronic structures of hydrogenated rare-earth glasses

众所周知，稀土（RE）-过渡金属（TM）-简单金属（SM）系统在宽的组成范围内容易形成玻璃态合金，并且对氢具有很强的反应性。本研究利用X射线衍射、X射线光电子能谱和热脱附谱等方法研究了La-Ni-Mg（Al）和Nd-Fe-B合金玻璃及其微晶玻璃的原子结构、电子结构和表面态。在所有这些系统中，玻璃结构由金属原子的随机堆积组成，然而，RE-TM相互作用得到加强。氢化通过形成强的RE-H化学键改变了无规结构，这破坏了RE-TM键并导致金属原子的微团簇。通过原子结构径向分布分析、光电子能谱、芯能级谱和价带谱的分析，一致地观察到了这种效应，在H/M=1.0-1.7范围内，氢可以被储存在玻璃中。详细研究了它们的吸放氢性能。特别是<40>La_5Ni_Mg_4<55>合金玻璃作为贮氢材料是有价值的，这些研究已在定期的论文中发表，并将在国际研讨会上发表。

It is well known that rare-earth (RE) -transition metal (TM)- simple metal (SM) systems readily form glassy alloys over wide composition ranges and are very reactive to hydrogen. In this research, atomic and electronic structures and surface states of La-Ni-Mg(Al) and Nd-Fe-B alloy glasses and their hydrides have been studied by means of X-ray diffraction, X-ray photoemission spectroscopy and thermal desorption spectrometry. In all these systems the glass structures consist of random packing of the metal atoms, where however RE-TM interaction is strengthened. Hydrogenation alters the random structures by forming strong RE-H chemical bonds, which break the RE-TM bonds and cause micro-clustering of metal atoms. This effect was observed by radial distribution analysis of atomic structure and photoemission core-level and valence-band spectra consistently.Hydrogen can be stored in these glasses by H/M=1.0-1.7 depending on the compositions. Their hydrogen absorption-desorption properties have been studied in detail. Specifically, La_5Ni_<40>Mg_<55> alloy glass is found to be profitable for use as a hydrogen storage material.These studies have been published in regular papers and are going to be presented at international symposiums.