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Showing 1 to 20 of 37 for “"spinels"”.
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The Magnetic Exchange Interactions in Chromium Chalcogenide Spinels
The chromium chalcogenide spinels, MCr2X4 (M = Zn, Cd, Hg; X = O, S, Se), have been the subject of considerable interest in recent years. In each case the crystal structure is that of a normal spinel with the chromium ions exclusively occupying the octahedral (B) sites, so that when diamagnetic …
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Raman scattering studies of spinels CoV2O4 and MnV2O4
… scattering studies of the strongly correlated spinels CoV2O4 and MnV2O4. In CoV2O4, exclusive attention is given to a triply degenerate (T2g) phonon in order to determine the material's structural properties and explore coupling between the lattice and other degrees of freedom. …
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Carbon deposition on transition metal- and uranium-oxides
… at deposition on a range of transition metal spinels, manganese oxides, uranium oxides and single crystal magnetite samples with a view to furthering knowledge of catalytic reactions that may occur within an AGR. In particular, the effect of mixed valency on deposition rates was studied. The …
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Diamonds and related minerals from the Dokolwayo Kimberlite, Kingdom of Swaziland
… for their compositions. Concentrate macrocryst spinels and silicate inclusions recovered from these spinels were analyzed. The physical characteristics of the diamonds investigated were mass, size, morphology and colour. The relationship between mass and size in a population of diamonds …
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Stability of lithium aluminum manganese oxide cathodes for rechargeable lithium batteries
… the transformation strains. (3) Al-doped spinels exhibit much improved capacity stability at elevated temperatures compared to undoped spinels. This effect has been discussed with respect to proposed mechanisms of Mn dissolution and capacity loss. (4) Magnetic properties are critically …
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Real-space magnetic imaging of the spinel MnV2O4
… understood. One such class of materials are the spinels, including MnV2O4. Bulk probe studies of this compound have yielded conflicting and inconclusive results. To inform the debate and better understand the underlying physics, we performed magnetic force microscopy measurements on two MnV2O4 …
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Textural and Chemical Relations Among Spinel-Sapphirine-Garnet-Orthopyroxene, Salt Hill Emery Mine, Cortlandt Complex, N.Y.
… into two groups: a more magnesian one containing spinels with average Fe/(Fe+Mg) (Fe#) of 0.49 and a less magnesian one, average Fe# of 0.67. With regard to this bulk compositional effect, the more magnesian composition should reduce garnet stability due to the strong fractionation of Fe into …
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Phosphate and thermal stabilization of heavy metals in dredged sediments
… phases, hopeite (Zn_3(PO_4)_2.4H_2O) (22%), and spinels, gahnite (ZnAl_2O_4) (44%) and franklinite (ZnFe_2O_4) (34%). Sequential extraction revealed similar shifts in metal forms from labile to recalcitrant residuals for Ni, Cu (spinels), Mn (crystalline oxides), Pb (phosphate mineral), Cd …
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Investigation of co1-2xnixmnxceyfe2-yo4 double-substitution spinel for highly efficient detection of flammable and hazardous liquefied petroleum gas: sensing performance
… consider. In this research, double substitution spinels with chemical formula Co1-2xNixMnxFe2-yCeyO4, where 0 ≤ x = y ≤ 0.3, were prepared via the glycol thermal technique. The final products following the appropriate substitution were CoFe2O4 (dried naturally), CoFe2O4 (dried with Infrared …
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Studies of Magmatic Systems
… of significant amounts of Ti in our magmatic spinels. Indeed Ti is not taken into account in the geothermometers. We tested the possibility of accounting for the presence and effects of Ti using a linear correction for the Fe+2 content in our spinels. While this generated more realistic …
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Enhanced Methane Oxidation Catalysis Through Feed Modulation And Oxygen Storage
… by mixed-metal oxides, otherwise known as spinels. We initially demonstrate the enhancements resulting from the combination of spinels and modulating feed conditions. Next, we optimize catalyst performance by examining the impact of different feed modulation parameters such as oscillation …
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Microchemical characterization of ash from fuel production
… and Ti and other trace elements. Fe oxides and spinels were common phases found. Pb and Zn were rarely encountered, but were found as both oxides and sulfides. Cr was found in the form of spinels, often covered by a protective AI enriched outer rim. The heavy metals found were successfully bound …
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Gahnite and its formation in the context of regional metamorphism and mineralization in the Namaqualand metamorphic complex
… during metamorphism. The stability of zinc-rich spinels under a wide range of metamorphic conditions in a variety of lithologies results in its persistence in rocks where many other prograde, high temperature minerals and sulphides have been altered. Thfs has resulted in various investigations …
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Mantle Wedge Evolution beneath the Northern Mariana Forearc
… reveal a wide range of variations in the Cr# of spinels from 0.28-0.83 indicating 16-23% of melt fraction generation. Though the extremely low TiO2 content (25-485 ppm) of the spinels indicates no melt-rock interaction, the presence of tiny (20-50 m) interstitial clinopyroxene (cpx) along with …
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Petroleum coke slags: characterization and dissolution
… slags are composed of V₂>0₄, nickel aluminum spinels. various vanadates and glass. Textural analysis provided information on the crystallization process, reaction with gasifier refractory lining materials, sulfide exsolution processes, glass devitrification. and the development of chemical …
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Compositional Analysis of the Martian Meteorites Northwest Africa 6342 and Northwest Africa 10961
… these meteorites. Poikilitic zones have Cr-rich spinels in the form of chromite while the nonpoikilitic areas exhibit Ti-rich spinels. NWA 6342 and NWA 10961 have experienced high levels of shock metamorphism as demonstrated by substantially fractured minerals, melting and subsequent …
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Imaging magnetic order in magneto-structural phases of Mn3O4
Frustration in A-site spinels due to the competition between complex structure and strong interactions has been the focus of many theoretical and experimental studies recently. Mn3O4 is one such material with a three way interplay between complex lattice geometry, strong spin-lattice coupling and …
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Timescales of magma residence and transport underneath Iceland
… for the zoning. Diffusive exchange in these spinels is primarily driven by cooling and exchange with the interstitial mush liquid. 2D diffusion modelling of Cr-Al exchange in the spinels indicates that the crystal mush was stored for approximately 1500 years. This is the first direct estimate …
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57Fe Mössbauer spectroscopic study of the spin-glass transitions in the mixed spinel series Mg0.9+xFe2(1-x)Ni0.1Ti0.1O4
… spin-glass behaviour. On the other hand, such spinels were also reported to exhibit a superparamagnetic behaviour due to the existence of small magnetic clusters in the spinel lattice. In order to gain some insight in this controversial problem, a 57Fe Mössbauer spectroscopic study has been …
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