@article{SchifferleLobanov2022, author = {Schifferle, Lukas and Lobanov, Sergey S.}, title = {Evolution of chemical bonding and spin-pairing energy in ferropericlase across Its spin transition}, series = {ACS Earth and Space Chemistry}, volume = {6}, journal = {ACS Earth and Space Chemistry}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {2472-3452}, doi = {10.1021/acsearthspacechem.2c00014}, pages = {788 -- 799}, year = {2022}, abstract = {The evolution of chemical bonding in ferropericlase, (Mg,Fe)O, with pressure may affect the physical and chemical properties of the Earth's lower mantle. Here, we report high-pressure optical absorption spectra of single-crystalline ferropericlase ((Mg0.87Fe0.13)O) up to 135 GPa. Combined with a re-evaluation of published partial fluorescence yield X-ray absorption spectroscopy data, we show that the covalency of the Fe-O bond increases with pressure, but the iron spin transition at 57-76.5 GPa reverses this trend. The qualitative crossover in chemical bonding suggests that the spin-pairing transition weakens the Fe-O bond in ferropericlase. We find, that the spin transition in ferropericlase is caused by both the increase of the ligand field-splitting energy and the decrease in the spin-pairing energy of high-spin Fe2+.}, language = {en} }