“…This understanding of the structure of boron carbides has been obtained from the analysis of experimental extended X-ray absorption fine structure (EXAFS) [32,36,37,39] and near edge X-ray adsorption fine structure [36,39]. The analysis providing the best fit of the unfiltered EXAFS data, even with doping levels of 50-200 ppm, is consistent with a model that has the transition metal Co [32,36,39], Mn [32] or Fe [32,37] atoms preferentially occupying positions in two adjoined icosahedral cages at the apical sites, likely at a boron or carbon site for each cage, as schematically shown in Fig. 1, and more extensively seen in the supplementary material.…”