Abstract In order to unveil the lattice structure of La-Fe-Si-(H) alloys from local atomic perspective and uncover its relation with macro-properties, local structural environments of La and Fe in stoichiometric and Fe-rich La-Fe-Si-(H) have been investigated by X-ray absorption fine structure (XAFS) technique. According to the curve-fitting and real space analysis of extended X-ray absorption fine structure (EXAFS) spectra at La L3-edge and Fe K-edge, we found that the interstitial hydrogen atoms preferentially occupy 24d site, which is not affected by the existence of second phase. X-ray absorption near edge structure (XANES) spectra of La atom give a clear evidence of valence electron transfer from hydrogen to Fe, indicating a close relation between electronic structure and capability of hydrogen absorption. The hybridization effect between Fe and Si is proved to play dominant role on Curie temperature (Tc) of La-Fe-Si alloys, but have limited influence on Tc for La-Fe-Si-(H) alloys. The study establishes strong correlation between the local structure and above properties in La-Fe-Si-(H) alloys.

中文翻译：

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La-Fe-Si(-H) 磁热合金的 X 射线吸收光谱研究

摘要 为了从局部原子的角度揭示 La-Fe-Si-(H) 合金的晶格结构，并揭示其与宏观性质、化学计量和富铁 La-Fe-Si 中 La 和 Fe 的局部结构环境的关系。 -(H) 已通过 X 射线吸收精细结构 (XAFS) 技术进行了研究。根据La L3-edge和Fe K-edge的扩展X射线吸收精细结构（EXAFS）光谱的曲线拟合和实空间分析，我们发现间隙氢原子优先占据24d位点，不受第二阶段的存在。La 原子的 X 射线吸收近边结构 (XANES) 光谱给出了价电子从氢转移到 Fe 的明确证据，表明电子结构与氢吸收能力之间存在密切关系。Fe和Si之间的杂化效应被证明对La-Fe-Si合金的居里温度（Tc）起主导作用，但对La-Fe-Si-（H）合金的Tc影响有限。该研究在 La-Fe-Si-(H) 合金的局部结构和上述性能之间建立了很强的相关性。