X射线吸收精细结构谱在材料科学中的应用

Application of X-ray absorption fine structure spectroscopy in materials science

简单介绍了X射线吸收精细结构谱的物理基础,数据处理方法,讨论了X射线吸收精细结构谱在元素组成,价态和结构环境方面的分析结果。结果显示,在钠钙硅酸盐平板玻璃中,二价铁离子和三价铁离子同时存在。在Ag-Na离子交换后,二价铁离子被银离子氧化成三价铁离子。当Ti2O3和锐钛矿被分别掺入硼硅酸盐玻璃后,钛离子主要以四价存在,Ti4+离子占据五重配位点。在玻璃中同时掺入锐钛矿和还原剂C,诱导三价钛离子生成,三价钛离子占据八面体配位点,使得Ti K边预边峰高度降低。包裹在钠钙硅酸盐玻璃中的银纳米颗粒界面存在张应力,使得银晶格膨胀,银原子存在两种结构环境:Ag-O配位和Ag-Ag配位。孤立银原子的存在,使得最近邻Ag-Ag配位数显著降低。

The physical origin and data analysis of extended X-ray absorption fine structure spectroscopy （EXAFS） and X-ray absorption near-edge spectroscopy （XANES） were introduced briefly. Its applications in detecting atomic constitute, valence state and structural environment were discussed. The results show that different valence states of iron ions usually exist simultaneously in soda-lime silicate glass matrix. After Ag^＋ for Na^＋ ionexchange, bivalent iron ions were oxidized into trivalent iron ions by silver ions. When Ti2O3 and anatase were doped into borosilicate glass,respectively, the oxidation state of titanium was mainly Ti^4＋. Ti^4＋ ions occupy five-fold coordination sites. When both anatase and C were doped into borosilicate glass, small amounts of Ti^3＋ ions exist in the form of oetahedral coordination sites besides large amounts of Ti^4＋ ions in five-fold coordination sites. The crystalline Ag nanoparticles embedded in soda-lime silicate glass exhibit a lattice dilatation, indicating the existence of tensile stress on Ag nanoparticles because of thermal expansion mismatch of Ag and the glass matrix. There are two kinds of Ag structural environments in the glass： Ag-O and Ag-Ag coordinations. The existence of Ag-O coordination induces a large decrease of Ag-Ag coordination number.