A high-pressure Mössbauer spectroscopy study of a spin crossover in $\left({\mathrm{Mg}}_{0.8}{\mathrm{Fe}}_{0.2}\right)\mathrm{O}$ ferropericlase is presented. A low-spin subspectral component appears at about $55\mathrm{GPa}$, but there is a significant pressure region over which both high-spin and low-spin states are stable, before the high-spin component disappears completely above $100\mathrm{GPa}$. These results are only partly consistent with recent x-ray emission spectroscopy (XES) results, and the discrepancy is likely due to assumptions used in analyzing the XES data that are not fully satisfied at high pressure. An alternative method of XES data analysis based on spectral decomposition is presented, which is fully consistent with the Mössbauer data and allows the extraction of additional information from the XES data.

• Received 16 November 2005

DOI:https://doi.org/10.1103/PhysRevB.73.100101