Researchers at Georgia Tech have been studying the relationship between synthesis conditions, particle size, and magnetic properties for a range of Ni1-xFe2+xO4 spinel compositions. To fully interpret the properties of the nanoparticles, synthesized with various heat treatments, the degree of inversion (interchange of Fe and Ni) in the spinel must be determined. Since the contrast between Ni and Fe is negligible for both neutrons and non-resonant x-rays, Prof. Wilkinson and Ms. Samia conducted resonant scattering experiments at HTML’s synchrotron beam line X14A with Drs. Jianming Bai and Claudia Rawn of the Diffraction User Center. To enhance the scattering contrast of the Fe and Ni data sets were collected near the Fe and Ni K-edges, while a third high-energy data set was collected for each sample at approximately 17 keV to define a baseline of structural parameters. Currently the data is being processed using Rietveld or whole-pattern-fitting structural refinement techniques, through which a powder pattern is calculated using a structural model and compared to the data. Structural information such as the atomic positions and site occupations will be used to determine the degree of inversion.