Local order of Ca in a CaF2-Al2O3-SiO2 glass by electron energy-loss spectroscopy

Local order of Ca in a CaF2-Al2O3-SiO2 glass is studied using electron energy loss spectroscopy technique. The energy shift of ionization threshold in the Ca L-2,L-3 and the differences in the near-edge structure of the Ca M-2,M-3 edge between the glasses with and without F suggest the local ordering of F around Ca in the F-containing aluminosilicate glass. The local order phenomenon requires the clustering of Ca-F. Therefore, the transparent fluorinated calcium aluminosilicate glass is not structurally and compositionally homogeneous at nanometer scale. (C) 2011 American Institute of Physics. [doi:10.1063/1.3608118]