Cryogenic EXAFS investigations of the short-range structural environment of gallium in PbO-Ga2O3 glasses

Gallium K-edge extended X-ray absorption fine structure (EXAFS) spectra of PbO-Ga2O3 glasses were recorded at liquid-nitrogen temperature (77 K) to understand the coordination scheme of gallium in these glasses. Four oxygens were found to be bonded to each Ga, forming GaO4 tetrahedra with an average bond distance of 1.855-1.862 Angstrom. Assuming a non-Gaussian distribution of Ga-O bond distances provided better results with a smaller R-factor compared to the Gaussian counterpart. Two-subshell fitting indicated that oxygens with Ga-O bond distance of similar to 1.87 Angstrom are bonded to three cations, while the shorter Ga-O bonded oxygens are two-coordinated. (C) 1999 Elsevier Science B.V. All rights reserved.