XPS Study of Iron Phosphate Glasses

X-ray photoelectron spectroscopy (XPS) has been used to characterize the short range structure of iron phosphate glasses. Quantitative Fe2+/Fe3+ ratios determined by decomposing the Fe3p spectra are in good agreement with valence measurements made by Mossbauer spectroscopy. Fe2+ is preferred when [Fe]/[P] is low, whereas Fe3+ is preferred when [Fe]/[P] is greater than approximately 0·4. Increasing [Fe]/[P] decreases the bridging to nonbridging oxygen ratio determined from the O1s spectra. It is shown that a quantitative relationship exists between this latter ratio and the glass composition and average Fe valence