XPS study of transition metal doped silicate glasses

Abstract

Abstract X-ray photoelectron spectroscopy (XPS) has been used to study the redox state of transition metal oxides in sodium silicate glasses with compositions 0.30Na 2 O–0.70SiO 2 and 0.3Na 2 O–0.6SiO 2 –0.1TMO, where TMO=Fe 2 O 3 , CuO and CoO. From the analysis of the core level spectra of the transition metals, it was found that both Fe 2+ and Fe 3+ exist simultaneously in the iron doped glass, while Cu + was the only species present in the copper doped glass. In the cobalt doped glass, Co 2+ was found to exist in both tetrahedral (tet) and octahedral (oct) co-ordinations. From the analysis of the O 1s spectra, it was possible to discriminate between bridging and non-bridging oxygen atoms in each glass sample. It was also shown that the non-bridging oxygen contribution to the O 1s spectra can be simulated by summing the contributions from SiONa, SiOFe 2+ and SiOFe 3+ for the iron doped glass, SiONa and SiOCu + for the copper doped glass and SiONa, SiOCo 2+ (tet) and SiOCo 2+ (oct) for the cobalt doped glass. The quantitative values for the [Fe 2+ ]/[Fe] and [Co 2+ (tet)]/[Co] concentrations ratios were found from the analysis of the Fe 3p and Co 3p core level spectra, respectively.