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Showing 1 to 20 of 23 for “"Cr₂O₃"”.
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Haloethane Reactions over the Chromia Cr₂O₃ (1012) Surface
… produce ethyl fragments on the stoichiometric α-Cr₂O₃ (1012) surface by means of thermal dissociation. Ethyl iodide is dissociated giving iodine adatoms and ethyl fragments bound to surface Cr cation sites, while ethyl chloride is dissociated giving chlorine adatoms and ethyl fragments. No …
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The Oxidation of Methanol on Cr₂O₃ (101̅2) Single Crystal Surfaces
… and oxygen-terminated surfaces of Cr₂O₃ (101̅2) was studied using thermal desorption spectroscopy and x-ray photoelectron spectroscopy. Dissociative adsorption of methanol occurs on the nearly-stoichiometric surface and is attributed to the presence of cation/anion site-pairs. An …
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Reactions of Halogenated Ethylenes on the α-Cr₂O₃ (101̅2) Surface
… reaction of halogenated ethylenes on the α-Cr₂O₃ (101̅2) single crystal surface results in the formation of gas phase hydrocarbons including acetylene, ethylene, butadiene, and dihydrogen, and deposition of surface chlorine adatoms. No surface carbon or combustion products are observed in …
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The Cr₃O-type compound in the niobium-rhodium-silicon ternary system
A series of compositions across the niobium-rhodium- silicon ternary diagram from Nb₃Rh to 75 atomic percent niobium-25 percent silicon, were prepared by arc-melting compacts of high-purity powders. Both x-ray diffractometer and camera techniques were used to analyze the resulting structures. No …
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Reaction chemistry of C₁ hydrocarbon fragments and oxygenates on Cr₂O₃ (101̅2)
… O-terminated, and Cl-terminated α-Cr₂O₃ surfaces, were studied by thermal desorption spectroscopy. Adsorbed formaldehyde forms dioxymethylene species on the nearly-stoichiometric surface that react primarily above 600 K. Dioxymethylene decomposes via a Cannizzaro-type process with …
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Geometric and Electronic Structure Sensitivity of Methyl and Methylene Reactions on α-Cr₂O₃ and α-Fe₂O₃ surfaces
… three different oxide single crystal surfaces: α-Cr₂O₃(101̅2), α-Cr₂O₃(0001), and α-Fe₂O₃(101̅2). The intermediates have been generated through the decomposition of halogenated hydrocarbons. The primary reactions of methyl and methylene over α-Cr₂O₃ are methyl dehydrogenation to methylene, and …
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Phase equilibria studies of Cr3O-type structures in the vanadium- rhodium-silicon and niobium-rhodium-silicon ternary systems
Phase equilibria studies of two ternary systems, the vanadium rhodium-silicon system and the niobium-rhodium-silicon system, were made to obtain information about the formation of the Cr₃O-type structure in these systems. All samples had compositions in the . vicinity of the stoichiometric Cr₃O …
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Scanning Tunneling Microscopy and Adsorption Studies on Single-Crystal Metal Oxide Surfaces
… adsorption was studied on the stoichiometric Cr₂O₃ (101̲2) surface, using thermal desorption spectroscopy (TDS). Water was the only desorption product observed during TDS. Adsorption is primarily dissociative following exposure to water at 163 K. Approximately, 0.12 monolayers of water …
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Halocarbon Reactions on the Chromium (III) Oxide (101̲2) Surface
A nearly stoichiometric, (1×1) Cr₂O₃ (101̲2) surface was prepared from a single crystal of α-Cr₂O₃. The five-coordinate cations exposed at the stoichiometric surface dissociatively adsorb molecular oxygen to form a (1×1), terminating chromyl (Cr=O) layer that is stable to >1100 K. TDS and AES were …
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Interaction of Acid/Base Probe Molecules with Specific Features on Well-Defined Metal Oxide Single-Crystal Surfaces
… crystal surfaces of Cu₂O (111), SnO₂ (110), and Cr₂O₃ (101̲2) were investigated for their acid/base properties by the interactions between the probe molecules and the well-defined surface features. The adsorption of NH₃ at cation sites was used to characterize the Lewis acidity of SnO₂ (110) and …
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Model Chromia Surface Chemistry: C<sub>2</sub> Alkyl Fragment Reactions and Probe Molecule Interactions
… ethanes on the nearly-stoichiometric α-Cr₂O₃ (102) surface results in the formation of gas phase hydrocarbons including ethylene, ethane, acetylene, 2-butene, 2-butyne and dihydrogen, and deposition of surface chlorine adatoms. No surface carbon or combustion products are observed in any …
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The measles defect in CA-15 alloy steel castings
… in which the chromium in the melt is oxidized to Cr₂O₃·Fe₂O₃ and Cr₂O₃·FeO. The mechanism was found to be akin to a pitting form of corrosion. The oxidizing atmosphere is provided by moisture in the molding material and carbon dioxide formed by the combustion of organic binders.
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Experimental Adsorption and Reaction Studies on Transition Metal Oxides Compared to DFT Simulations
… On the nearly-stoichiometric surface of α-Cr₂O₃(101̅2), CD₃₋ undergoes dehydrogenation to produce CD₂=CD₂ and CD₄. Previous TPD traces suggest that the α-hydrogen (α-H) elimination of methyl groups on α-Cr₂O₃(101̅2) is the rate-limiting step, and has an activation barrier of 135±2 kJ/mol. …
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Atomic size factor and the Cr3O-type compound in the Cr-Si-Sn ternary system
An investigation was conducted to determine if Sn atoms could be substituted for Si atoms in the compound Cr₃Si. Prom size factor considerations, the feasibility that this substitution should occur seemed reasonable. However, attempts to make the substitution were unsuccessful. A model of the …
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Electronic thermal conductivity of superconducting lead-manganese, indium-manganese, and indium-chromium alloy films
Measurements have been made of the electronic thermal conductivity of quench-condensed films of lead-manganese and indium-manganese alloys. The results are compared with calculations based on Shiba's theory of superconductors containing magnetic impurities. For Pb-Mn, the value of £ (the normalized …
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Cation-disordered oxides for rechargeable lithium battery cathodes
The demands for high-energy density cathode materials for rechargeable lithium batteries are ever increasing. This is because such cathode materials will enable smaller and lighter rechargeable lithium batteries for complex applications such as in electric vehicles or in grid energy storage. Nearly …
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Optimisation of an industrial scale ball mill using an online pulp and ball load sensor
… and analysed for grind as well as PGM and Cr₂O₃ content. The majority of the PGM's in the UG2 ore are in the silicates and thus the PGM distribution results would indicate the amount of breakage in the silicate fraction. Cr₂O₃ is used as an indicator of the chromite content in UG2 ore. In …
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Induced Phase Transition in Magnetoelectric BiFeO3 Crystals, Thin-layers and Ceramics
… greater than that of any other material (cg., Cr₂O₃ ∼2.5x10⁻¹⁰ s/m), and many order(s) of magnitude higher than unmodified BiFeO₃ crystals. The data also reveal: (i) that ∝p is due to a linear coupling between polarization and magnetization; and (ii) that ∝p is independent of dc magnetic bias …
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Oxyanion Adsorption by Iron and Ruthenium Oxides: A Macroscopic, Spectroscopic, and Kinetic Investigation
The adsorption and desorption behavior of trace element contaminants was evaluated solids—goethite and ruthenium oxide. The importance of anion displacement as a mechanism responsible for arsenic release from iron oxides was investigated on goethite. The adsorption and polymerization of silicate on …
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Formation and Quantification of Corrosion Deposits in the Power Industry
The presence of deposits on the secondary side of pressurized water reactor (PWR) steam generator systems is one of the main contributors to the high maintenance costs of these generators. Formation and transport of corrosion products formed due to the presence of impurities, metals and metallic …
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