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Free keywords:
Dichroism; Iron; Iron oxides; Magnetic moments; Magnetite; X ray absorption; X ray absorption near edge structure spectroscopy, Magnetic circular dichroisms; Normal-spinel structure; Ordered magnetic moments; Pressure-induced phase transition; Stoichiometric magnetite; Structural transitions; Theoretical simulation; X-ray absorption near-edge structure spectra, Potassium compounds
Abstract:
Using a highly stoichiometric magnetite, the pressure-induced phase transitions of Fe3O4 have been revisited here by performing Fe K-edge X-ray absorption and magnetic circular dichroism measurements up to P = 65 GPa at room temperature and 71 GPa at 20 K. We have observed a structural transition at around 27 GPa from magnetite to a high-pressure phase h-Fe3O4 with the loss of the net ordered magnetic moments for both temperatures. The orthorhombic CaTi2O4-type (Bbmm) structure of the high-pressure phase h-Fe3O4 has been determined by combining experimental studies and theoretical simulations of the Fe K-edge X-ray absorption near-edge structure spectra. The long-time discussed pressure induced spin crossover, and inverse to normal spinel structure transitions in Fe3O4 can be deterministically excluded from the present study up to ∼65 GPa. © 2019 American Chemical Society.
