Chinese Acad Sci, Inst High Energy Phys, Beijing Synchrotron Radiat Facil, Beijing 100039, Peoples R China
; Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Italy
; Univ Roma Tre, Dipartimento Sci Geol, I-00146 Rome, Italy
Near-edge features of Al x-ray absorption near-edge structure (XANES) spectra in aluminosilicate compounds with mixed coordination number are usually assigned to a fourfold coordinated site contribution followed by a sixfold coordinated site contribution that is displaced towards higher energy because of the increasing ligand nucleus potentials, neglecting possible contributions due to bond distance variations and local geometrical distortion. Here we present and discuss the Al K-edge XANES spectra of synthetic micas with either fourfold coordinated Al (phlogopite), or with sixfold coordinated Al (polylithionite), as well as with mixed coordination (preiswerkite). Multiple scattering simulations of XANES spectra demonstrate that octahedral contributions may overlap the tetrahedral ones so that the lower energy structures in mixed coordination compounds may be associated with the octahedral sites. This unexpected behaviour can be described as due to the effect of a significant reduction of the ligand field strength (i.e. large local distortion and Al-O bond distances).
Wu ZY,Wu, ZY,Marcelli, A,et al. Investigation of the mica x-ray absorption near-edge structure spectral features at the Al K-edge[J]. JOURNAL OF PHYSICS-CONDENSED MATTER,2003,15(41):7139-7148.
吴自玉,Wu, ZY,Marcelli, A,Cibin, G,Mottana, A,&Della Ventura, G.(2003).Investigation of the mica x-ray absorption near-edge structure spectral features at the Al K-edge.JOURNAL OF PHYSICS-CONDENSED MATTER,15(41),7139-7148.
吴自玉,et al."Investigation of the mica x-ray absorption near-edge structure spectral features at the Al K-edge".JOURNAL OF PHYSICS-CONDENSED MATTER 15.41(2003):7139-7148.