Corundum structure oxides

The growth of vanadium oxide overlayers on Rh(l 11) converges after a number of intermediate stages to the formation of a three-dimensional bulk-like epitaxial V203 film [90], which is oriented with the (0 0 01) plane of its corundum structure parallel to the Rh(l 1 1) substrate surface. The V203 phase is the thermodynamically stable... 

The presence of relatively small Cr3 1 cations and the close-packed corundum structure anions suggest that Schottky defects will be preferred. Oxidation will add anions and reduction will remove anions. The four equilibria can now be written. 

The ilmenite structure is adopted by oxides of formula ABO3 when A and B are similar in size and their total charge adds up to +6. The structure is named after the mineral of Fe Ti" 03, and the structure is very similar to the corundum structure described... 

Unfortunately, any attempt to reduce ferric oxide results in the formation of magnetite as a distinct separate phase, and there is no solubility of this spinel in the corundum structure ( 5, 6). Thus, all the properties reported above for were... 

Some trivalent metal oxides adopt the corundum structure. Table 10.2.5 lists these compounds and the parameters of their hexagonal unit cells. 

The corundum structure is assumed by three oxides of primary importance in catalysis, namely, o -C.r2(b, w-AbCF, and a-FeiOy (which, inter alia, form solid solutions in the complete compositional range) (21, 27). The three-dimensional arrangement of the ions in this hexagonal structure consists of a hexagonal close-packed array of anions with the cations occupying two-thirds of the octahedral interstices. 

The oxide Ti203 (corundum structure) is obtained by reducing Ti02 at 1000°C in a stream of H2. It is rather inert and is attacked only by oxidizing acids. The addition of OH- ions to aqueous Ti111 solutions gives a purple precipitate of the hydrous oxide. 

Aqua regia literally royal water , so called because it will dissolve gold a mixture of three parts concentrated hydrochloric acid to one part concentrated nitric acid Corundum structure o -alnminnm oxide stmctnre Electrochemical oxidation oxidation of a solnte by passing a direct electrical cnrrent through its solution (e.g. chlorine is produced industrially by the electrochemical oxidation of the chloride ion)... 

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