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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
(FeO3)8O2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional and consists of two water molecules and one FeO3 framework. In the FeO3 framework, there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Fe–O bond distances ranging from 1.82–2.21 Å. In the second Fe site, Fe is bonded to six O atoms to form corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–58°. There are a spread of Fe–O bond distances ranging from 1.82–2.26 Å. There are four inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to two Fe and one O atom. The O–O bond length is 1.37 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the third O site, O is bonded in a trigonal planar geometry to two equivalent Fe and one O atom. The O–O bond length is 1.39 Å. In the fourth O site, O is bonded in a trigonal planar geometry to two equivalent Fe and one O atom.
(FeO3)8O2 is Upper Bainite-like structured and crystallizes in the orthorhombic Immm space group. The structure is three-dimensional and consists of two water molecules and one FeO3 framework. In the FeO3 framework, Fe is bonded to six O atoms to form corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.92–2.03 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Fe atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two equivalent Fe atoms. In the third O site, O is bonded in a bent 120 degrees geometry to two equivalent Fe atoms.
FeO3SO3 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four sulfur trioxide molecules and four FeO3 clusters. In each FeO3 cluster, Fe is bonded in a distorted trigonal non-coplanar geometry to three O atoms. All Fe–O bond lengths are 1.62 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Fe atom. In the second O site, O is bonded in a single-bond geometry to one Fe atom. In the third O site, O is bonded in a single-bond geometry to one Fe atom.
Multiferroics that combine ferroelectricity and magnetic order are attractive for electronic and spintronic technologies, yet chemical disorder that promotes relaxor ferroelectricity usually suppresses long-range magnetic order. Here, we report entropy-stabilized relaxor multiferroicity in epitaxial hexagonal (Tb0.2Dy0.2Ho0.2Lu0.2Yb0.2)FeO3 thin films. Structural, magnetic, dielectric, and synchrotron spectroscopic measurements show the coexistence of relaxor ferroelectricity and long-range ferromagnetic order. We find that improper ferroelectricity remains robust against A-site configurational disorder, while the Fe sublattice preserves magnetic exchange. This separation of the microscopic origins of the polar and magnetic responses enables chemically disordered multiferroicity. Our results establish entropy engineering in hexagonal ferrites as a route toward multifunctional oxide thin films and provide a general design strategy for high-entropy multiferroics.
The transition metal oxides (TMOs) V2O5, FeO3, Co3O4, NiO, CuO, and ZnO were exposed to hydrazine at various pressures. The metallic surfaces were surveyed by in situ X-ray photoelectron spectroscopy to determine the irrelative rate of reduction by hydrazine. The most easily reducible oxide, CuO, could be reduced to the metallic state at room temperature and 10 to the -6th torr. The reaction is first order with respect to CuO, with an activation energy of about 35 kJ/mol. Two types of adsorption were seen to occur at 295 K: (1) a reversible component in which the measured N:Cu ratio increased to 0.60 at hydrazine pressures up to 0.5 torr, and (2) an irreversible component, with a N:Cu ratio of 0.28, which could not be removed by extended vacuum pumping. The results of this study are useful for the identification of TMO's that can be used as solid neatallizers of hydrazine spills, and for the preparation of metal surfaces for electroplating and evaporative thin-film coating.
A core drilled near Wolhaarkop in Griqualand West, South Africa, intersected highly oxidized Kuruman Iron Formation below red beds of the Gamagara Formation. The lateral equivalents of the Kuruman Iron Formation in this drill hole consist largely of siderite, ankerite, magnetite, greenalite, and quartz. The oxidation of the Kuruman Iron Formation in WOL 2 occurred almost certainly during weathering prior to the deposition of the Gamagara Formation. The date of this weathering episode is bracketed between about 2.2 and 1.9 bybp by the age of the Ongeluk lavas in the Transvaal sequence below the unconformity and by the age of the Hartley lavas in the Olifantshoek Group above the unconformity. The ratio of iron to SiO2 in the several facies of the weathered Kuruman Iron Formation in WOL 2 is nearly the same as that in their unweathered equivalents. Since SiO2 loss during weathering was almost certainly minor, the similarity of the Fe/SiO2 ratio in the weathered and unweathered BIF indicates that nearly all the "FeO" in the Kuruman Iron Formation was oxidized and retained as FeO3 during weathering. Such a high degree of iron retention is best explained by an O2 content of the atmosphere > or = 0.03 atm at the time of weathering. Such an O2 pressure is very much greater than that suggested by the composition of paleosols developed on basalt > or = 2.2 bybp but is consistent with the highly oxidized nature of the 1.85 by Flin Flon paleosol. The new data suggest that PO2 rose dramatically from about 1 percent PAL (present atmospheric level) to > or = 15 percent PAL between 2.2 and 1.9 bybp.