Three Oxidation States of Manganese in the Barium Hexaferrite BaFe12-xMnxO19.

Title	Three Oxidation States of Manganese in the Barium Hexaferrite BaFe12-xMnxO19.
Authors	S. Nemrava; D.A. Vinnik; Z. Hu; M. Valldor; C.Y. Kuo; D.A. Zherebtsov; S.A. Gudkova; C.T. Chen; L.Hao Tjeng; R. Niewa
Journal	Inorg Chem
DOI	10.1021/acs.inorgchem.6b02688
Abstract	The coexistence of three valence states of Mn ions, namely, +2, +3, and +4, in substituted magnetoplumbite-type BaFe12-xMnxO19 was observed by soft X-ray absorption spectroscopy at the Mn-L2,3 edge. We infer that the occurrence of multiple valence states of Mn situated in the pristine purely iron(III) compound BaFe12O19 is made possible by the fact that the charge disproportionation of Mn(3+) into Mn(2+) and Mn(4+) requires less energy than that of Fe(3+) into Fe(2+) and Fe(4+), related to the smaller effective Coulomb interaction of Mn(3+) (d(4)) compared to Fe(3+) (d(5)). The different chemical environments determine the location of the differently charged ions: with Mn(3+) occupying positions with (distorted) octahedral local symmetry, Mn(4+) ions prefer octahedrally coordinated sites in order to optimize their covalent bonding. Larger and more ionic bonded Mn(2+) ions with a spherical charge distribution accumulate at tetrahedrally coordinated sites. Simulations of the experimental Mn-L2,3 XAS spectra of two different samples with x = 1.5 and x = 1.7 led to Mn(2+):Mn(3+):Mn(4+) atomic ratios of 0.16:0.51:0.33 and 0.19:0.57:0.24.
Citation	S. Nemrava; D.A. Vinnik; Z. Hu; M. Valldor; C.Y. Kuo; D.A. Zherebtsov; S.A. Gudkova; C.T. Chen; L.Hao Tjeng; R. Niewa.Three Oxidation States of Manganese in the Barium Hexaferrite BaFe12-xMnxO19.. Inorg Chem. 2017;56(7):38613866. doi:10.1021/acs.inorgchem.6b02688

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56 Ba 137.327000000 Barium

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Manganese

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Iron

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