The Role of Atmosphere on Phase Transformations and Magnetic Properties of Ulvospinel

We have synthesized the antiferromagnetic mineral ulvospinel, Fe 2 TiO 4, in Ar to assess the role of inert atmosphere on phase formation and magnetic properties. We report the role of atmosphere on a possible phase transition and the magnetic properties of this mineral. Atmosphere dependent transformations of ulvospinel are observed with increasing temperature. Oxidation of ulvospinel to form metastable titanomaghemite is shown to occur at 300° in atmospheric conditions. Only slight titanomaghematitzation was observed in samples transformed under pressure in in situ temperature dependent X-ray experiments. Formation of ilmenite and hematite from ulvospinel was observed under high temperature, high pressure, and low oxygen atmosphere conditions. This work is supported by the National Science Foundation (NSF) through Award DMR1106943 and the Spanish National Space Program of R&D Externalization through the project PRI-PIBUS-2011-1150. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. Use of the HPCAT facility was supported by DOE-BES, DOE-NNSA (CDAC), NSF, DOD-TACOM, and the W. M. Keck Foundation. Use of the APS was supported by DOE-BES, under Contract DE-AC02-06CH11357. Peerreview