Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

摘要: Abstract Soft X-ray absorption near edge spectroscopy (XANES) and extended fine structure (EXAFS) have been performed at the Mg-, Al- Si-K edges in order to establish ability of this derive structural information disordered solids such as glasses gels. Mg- Al-K XANES are good probes determine coordination state these elements important minerals, In a CaO MgO 2SiO2 glass Mg spectra differ from that found crystalline equivalent, with significant shift maxima lower energy, consistent CN than 6. Mg-EXAFS on same sample agreement indicate presence 5-coordinated O distances 2.01A. aluminosilicate gels, Al K has used investigate [4]Al/Altotal ratios. These ratios increase Al/Si decrease. Aluminosilicate ferric-silicate gels were studied by using Si XANES. significantly among samples studied. Al/Si= 1 present different local environment known clay minerals ratio. The gel-to-mineral transformation thus implies dissolution-recrystallization mechanism. On contrary, gel presents close nontronite which may be formed long range ordering initial