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Metal oxide systems

Investigations carried out within the past few years have revealed that multicomponent metal oxide systems may interact at interfaces by having one component form a two-dimensional metal oxide overlayer on the second metal oxide component. For example, vanadium oxide can be dispersed on Ti02, Zr02, Si02, AI2O3, and... [Pg.465]

This chapter presents detailed and thorough studies of chemical synthesis in three quite different chemical systems zinc ferrite, intermetallic, and metal oxide. In addition to different reaction types (oxide-oxide, metal-metal, and metal oxide), the systems have quite different heats of reaction. The oxide-oxide system has no heat of reaction, while the intermetallic has a significant, but modest, heat of reaction. The metal oxide system has a very large heat of reaction. The various observations appear to be consistent with the proposed conceptual models involving configuration, activation, mixing, and heating required to describe the mechanisms of shock-induced solid state chemistry. [Pg.194]

As indicated above, when a positive direct current is impressed upon a piece of titanium immersed in an electrolyte, the consequent rise in potential induces the formation of a protective surface film, which is resistant to passage of any further appreciable quantity of current into the electrolyte. The upper potential limit that can be attained without breakdown of the surface film will depend upon the nature of the electrolyte. Thus, in strong sulphuric acid the metal/oxide system will sustain voltages of between 80 and 100 V before a spark-type dielectric rupture ensues, while in sodium chloride solutions or in sea water film rupture takes place when the voltage across the oxide film reaches a value of about 12 to 14 V. Above the critical voltage, anodic dissolution takes place at weak spots in the surface film and appreciable current passes into the electrolyte, presumably by an initial mechanism involving the formation of soluble titanium ions. [Pg.878]

Metal Clusters and Extended Metal-Metal Bonding in Metal Oxide Systems... [Pg.263]

Metal clusters in metal oxide systems have not been well-characterized or abundantly investigated up to the present time. Only isolated examples of metal-metal bonded units in oxide lattices have appeared from time to time. It will be the thesis of this presentation to show that highly unusual structures determined by strong metal-metal bonding will be found in ternary and quaternary metal oxide systems, and that opportunities abound for creative work on the synthesis, theory and structure-property relationships of such compounds. Because of the well-known correlation of d-electron population and d-orbital radial extension with metal-metal bond formation,... [Pg.263]

The first compound containing a well-characterized cluster in a metal oxide system was Zn2Mo308, reported in 1957 by McCarroll, Katz and Ward (11,12). In this compound the M03OQ cluster units are constructed such that three Mo08 octahedra share common edges, and share 0 atoms with adjacent cluster units as reflected in the connectivity formula / 2 O3/ 3 ... [Pg.265]

S02 and NOx in flue gas from coal combustion contribute to smog and acid rain. Methods to remove these pollutants include alkaline wet scrubber systems that fix S02 to solid CaS04, and selective catalytic reduction by metal/metal oxide systems of NO/NOz to N2 and steam in the presence of ammonia. Particulate active carbons have also been used in flue gas decontamination, especially as they avoid costly scrubber processes and can operate at lower temperatures. The potential of active carbon fibers in this application has been explored by a... [Pg.123]

Instead of electrostatic (or physical) adsorption, metal uptake onto oxides might be considered chemical in nature. In chemical mechanisms, the metal precursor is envisioned to react with the oxide surface, involving as surface-ligand exchange [13,14] in which OH groups from the surface replace ligands in the adsorbing metal complex. In this section it will be shown that a relatively simple electrostatic interpretation of the adsorption of a number of catalyst precursors is the most reasonable one for a number of noble metal/oxide systems. [Pg.166]

Gloom for Oxide Superconductors Dismayed at the progress through the years, even with the most promising room-temperature metallic, binary oxides, many scientists abandoned the search for new high temperature oxide superconductors. Also, it should be mentioned that a deep-rooted prejudice had developed which claimed that the BCS theory had imposed a maximum transition temperature limit of 25 K for all superconducting materials, and that this temperature had already been achieved in certain alloys of niobium. Some scientists, however, were steadfast in their determination to break this barrier, optimistic in their outlook, and they continued their search for this unusual phenomenon in other metallic oxide systems. [Pg.19]

Single and mixed metal oxide systems redox pathways and anion deficiency... [Pg.82]

Examples of other mixed metal oxide systems 125... [Pg.125]


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Case Studies Selected Oxide-Metal Systems

Complementary metal-oxide sensor system

Curing system metal oxides

Highly Dispersed Transition Metal Ions in Oxides or Zeotype-Systems by PL Spectroscopy

Metal Oxides Involved in Energy Storage System

Metal-oxide sensors sensor system

Mixed Metal Oxide-(Organo) Silica Systems

Oxidation systems

Oxidative systems

Oxide systems

Systems involving direct oxidation by metal ions

Systems of Metal Nitrates with Oxidizers

Systems of Metal Nitrites with Oxidizers

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