Investigation of coordination number in silicate and germanate glasses using O K-edge X-ray absorption spectroscopy

A series of titanium silicate and alkali germanate glasses have been examined using oxygen K-edge X-ray absorption near edge structure (XANES) spectroscopy. Peaks in the O K-edge spectra due to O 1s to O 2p σ* states hybridized with cation s, p and d states can be used to determine the coordination of the Ti or Ge within the glass network. The O K-edge XANES data for the titanium silicate glasses is consistent with earlier Ti L-edge findings concerning the Ti environment in these glasses. The O K-edge XANES data of the alkali germanate glasses confirm that there is no formation of sixfold Ge within the glass before the germanate anomaly maximum. Fivefold Ge is observed in the alkali germanate glasses but only in compositions at the germanate anomaly maximum and beyond.