Mixed metal oxides, deposition

This section provides a comprehensive tabular summary of mixed metal oxide deposition, complementary to the books edited by Rees Jr. and by Jones and O Brien, focusing on the literature dealing with metal enolate precursors published after 1996. 

Inorganic Metal oxide materials Base single or mixed metal oxides Deposition method and conditions of base metal oxide(s) Annealing method and conditions Dopant(s) Doping method and conditions Purity of materials... 

The active coating consists of a thermally deposited mixed metal oxide coating, the composition of which is considered proprietary information, although it is known that certain filler materials, e.g. Ta, may be added to the mixed metal oxide to reduce the precious metal content of the coating, and hence the cost of the anode. 

In the case of MnO/ ( it is known to reduce on the surface of CNTs and graphene spontaneously to produce Mn02 NPs [182,183]. Solvothermal assisted precipitation of metal oxides can occur in milder solutions [184]. For example, mixed metal oxide NPs of CoFe204 have been deposited on GO from metallic salt precursors via the addition of ethanolamine followed by incubation at 180 °C in a sealed vessel [185]. Mixing GO with Cd2+ in DMSO followed by solvothermal treatment has been shown to both reduce GO to RGO and coat with CdS QDs [186]. 

After heating, the EB is mixed with superheated steam and fed to the first stage reactor. Both the first and second stage reactors are packed with a catalyst of metal oxide deposited on an activated charcoal or alumina pellets. Iron oxide, sometimes combined with chromium oxide or potassium carbonate, is commonly used. 

The deposition of mixed metal oxides is based on the deposition techniques and precursors used for the formation of metal oxides discussed earlier in this chapter. The most important publications in the held of high-temperature superconducting materials produced from metal enolates since the date of release of Rees book in 1996 are summarized in Table 8. 

TABLE 11. Deposition of miscellaneous mixed metal oxides... 

Mixed metal oxide Precursors Deposition method References... 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

Metal oxide catalysts are extensively employed in the chemical, petroleum and pollution control industries as oxidation catalysts (e.g., oxidation of methanol to formaldehyde, oxidation of o-xylene to phthalic anhydride, ammoxidation of propylene/propane to acrylonitrile, selective oxidation of HjS to elemental sulfur (SuperClaus) or SO2/SO3, selective catalytic reduction (SCR) of NO, with NHj, catalytic combustion of VOCs, etc.)- A special class of metal oxide catalysts consists of supported metal oxide catalysts, where an active phase (e.g., vanadium oxide) is deposited on a high surface area oxide support (e.g., alumina, titania, ziiconia, niobia, ceria, etc.). Supported metal oxide catalysts provide several advantages over bulk mixed metal oxide catalysts for fundamental studies since (1) the number of surface active sites can be controlled because the active metal oxide is 100% dispersed on the oxide support below monolayer coverage,... 

In the case of other transition metals, their alkoxides are not suitable as metal sources. Furthermore, a two-step method in which deposited metal salts are solidified by a reaction with oxalate or a base is not suitable for the preparation of ordered macroporous mixed metal oxides. Each metal has a different reactivity with oxalic acid or a base, and the produced oxalate or metal hydoxide has different solubilities in the reacting media, which causes a mixed metal oxide with an undesired metal ratio.On the other hand, in situ methods, in which an additive such as EG, citric acid or EDTA is present with mixed metals, ensure the chemical homogeneity of the products and are suitable methods for producing ordered macroporous mixed metal oxides with a desired ratio. Synthesis methods, structural characterisation and applications of macroporous mixed metal oxides are summarised in Table 3.4. 

Preparation of Various Mixed Metal Oxides. In order to deposit the mixed metal oxide, Pb(Zro.5Tio.5)03 a 2 1 1 stoichiometric solution of the lead, zirconium and titanium precursors was prepared. An amorphous film of these precursors was prepared by spin coating on silicon. 

For the electro winning of nickel, a tubular anode constructed from titanium with a mixed metal oxide coating is employed. In a standard design EMEW cell, the anode is approximately 50mm in diameter. The cathode is a stainless steel tube approximately 151 mm in diameter. Both the anode and cathode are fixed in the cell. A thin stainless steel starter sheet is rolled and inserted in the cell to deposit nickel. The deposited nickel cathode is removed from the cell as a tube. The stainless steel starter sheet then springs off the deposit to release the nickel cathode. 

Excellent summary lists of publications where the TAP technique is applied to different catalytic systems can be found in [79, 80]. These lists include the many types of catalytic materials that are studied including supported metals, mixed metal oxides, zeolites, metal particles, metals deposited on screens, catalytic monoliths, and nanoparticles or atoms deposited on microparticles, single crystals, and other model catalysts. 

Michel H-J, Michel H-J, Leiste H, Halbritter J (1995) Structural and electrical characterization of PVD-deposited SnO films for gas-sensor application. Sens Actuators B 24-25 568-572 Miura N, Yamazoe N (1998) High-temperature potentiometric/amperometric NO sensors combining stabilized zirconia with mixed-metal oxide electrode. Sens Actuators B 52 169-178 Miura N, Lu G, Yamazoe N, Kurosawa H, Hasei M (1996) Mixed potential type NOx sensor based on stabilized zirconia and oxide electrode. J Electrochem Soc 143 L33-L35... 

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