Hybrid Structure Analysis: Accurate and Precise Determination of the Structure Parameters of Mono- and Bimetallic Spinels by Iterative and Alternating Refinements of Powder X-ray Diffraction and X-ray Absorption Fine Structure

Abstract

Abstract Structure parameters, such as bond length, bond angle, and occupancy of each atomic site, considerably affect the activity of solid catalysts and the physical properties of electronic and magnetic materials. Precise structure analysis, including accurate estimation of these parameters by powder X-ray diffraction (PXRD), is very important in the development of materials. Occupancy, however, is highly correlated with atomic displacement parameters, making determining accurate values by PXRD difficult, particularly in cases where atoms with similar atomic numbers share the same site. Here, we present an accurate and precise hybrid structure analysis of two electrocatalysts, spinels Co3O4 and Co2MnO4, combining the advantages of both PXRD and X-ray absorption fine structure (XAFS). More accurate information on the bond length and the distribution of chemical species by XAFS was incorporated into the precise Rietveld refinement of PXRD data. Accurate and precise structure parameters, including occupancy of each atom, were determined using the proposed method, which could be a useful basis for clarifying the mechanism of catalytic reactions.