X-ray absorption spectroscopic investigation of the environment of cerium in glasses based on complex cerium alkali borosilicate compositions

We present the results of cerium L-III X-ray absorption near edge structure (XANES) studies of two series (-I and -II) of alkali boro-aluminosilicate based glasses prepared from compositions containing different amounts of CeO2 and P2O5, and melted at a variety of temperatures and redox conditions. Model XANES spectra for Ce3+ in the glass, Ce4+ in the glass, and crystalline CeO2, were used to fit the Ce L-III XANES spectra obtained from the glasses. This analysis allowed both the [Ce4+]/[Ce-total] ratio and the distribution of Ce environments to be determined for each glass. The [Ce4+]/[Ce-total] ratios, which varied from 0.00 to 0.58, determined independently by XANES spectroscopy were found to have a correlation, r > 0.9, with those previously obtained using wet chemical methods. Furthermore, using this method, these two series of glasses, which differed in the amounts of BaO, Bi2O3, SnO2, and ZrO2, had different distributions in their cerium environments. The Ce L-III XANES spectra obtained from series II glasses (1.0 wt% BaO, 1.0 wt% Bi2O3, no SnO2, and 1.0 wt% ZrO2) melted at 1350 degrees C were able to be fit using only Ce-glass(3+) and Ce-glass(4+) environments; whereas, those from series I glasses (2.7 wt% SnO2, no BaO or Bi2O3, and 5.1 wt% ZrO2) melted at 1120 degrees C could only be fit when an additional Ce-CeO2(4+) component was included, confirming the previous assessment that the series I glasses exhibited CeO2 related heterogeneities. (C) 1998 Elsevier Science B.V. All rights reserved.