Structure Identification of Ni-Fe Oxide Mixture using Raman Spectroscopy, and X-ray Absorption Near-Edge Spectroscopy

Abstract

Advancement in instrumentation has made identification of metal structures easier with respect to determining structure and how multiple metals in a structure affect one another. The metal NiO was examined to see how the addition of Fe changes the structure of NiO. Raman spectroscopy and the X-ray absorption near-edge spectroscopy (XANES) was used to find the structure of the Ni-Fe oxide mixture. The Raman spectrum showed that at 10% mol Fe composition a spinel structure was formed compared to the face-centered cubic structure of NiO. Since the spectrum showed a spinel structure, it suggested either the Fe or the Ni from the mixed oxide would have a tetrahedral coordination or an octahedral coordination. XANES showed that the structure of the Fe in the mixture had a tetrahedral structure, which meant that Ni had the octahedral structure. Since Ni and Fe were found to be in the opposite position of what normally is expected of a spinel structure, the Ni-Fe oxide mixture has an inverse spinel structure.