Investigation of coordination changes in substituted transition-metal oxides by K-edge XANES: Beyond the pre-edge

Abstract

Transition-metal oxides are important materials whose properties can be tuned through selective substitution of the constituent elements. For oxygen deficient materials, substitution can lead to variations in coordination number (CN). To understand these changes in CN, the pre-edge peak intensity, resulting primarily from a 1s to n-1d transition, from first-row transition-metal K-edge XANES spectra can be used. However, investigation of these peaks from spectra of second-row transition-metals can be difficult owing to lower spectral resolutions. It is shown here, through examination of Ca 2Fe 2− x Ga x O 5, SrFe 1− x Zr x O 3− δ , and (ZrO 2) x (SiO 2) 1− x , that changes in CN also lead to significant variations of the main absorption edge.