Dioxide mixed oxides

Nitrogen tetroxide always is formed along with nitrogen dioxide during preparation of the dioxide (See Nitrogen Dioxide.) Mixed oxides are produced by oxidation of nitric oxide (NO) in air, heating metal nitrates, or by metals reacting with nitric acids or nitrates. 

Silica-germanium dioxide mixed oxides have attracted considerable interest due to their various appealing properties, which make them interesting materials for opties, non-linear opties, [153] photonies [154],... 

Titanium IV) oxide, T1O2. See titanium dioxide. Dissolves in concentrated alkali hydroxides to give titanates. Mixed metal oxides, many of commercial importance, are formed by TiOj. CaTiOj is perovskite. BaTiOa, per-ovskite related structure, is piezoelectric and is used in transducers in ultrasonic apparatus and gramophone pickups and also as a polishing compound. Other mixed oxides have the il-menite structure (e.g. FeTiOj) and the spinel structure (e.g. MgjTiO ). 

Alkaline-Earth Titanates. Some physical properties of representative alkaline-earth titanates ate Hsted in Table 15. The most important apphcations of these titanates are in the manufacture of electronic components (109). The most important member of the class is barium titanate, BaTi03, which owes its significance to its exceptionally high dielectric constant and its piezoelectric and ferroelectric properties. Further, because barium titanate easily forms solid solutions with strontium titanate, lead titanate, zirconium oxide, and tin oxide, the electrical properties can be modified within wide limits. Barium titanate may be made by, eg, cocalcination of barium carbonate and titanium dioxide at ca 1200°C. With the exception of Ba2Ti04, barium orthotitanate, titanates do not contain discrete TiO ions but ate mixed oxides. Ba2Ti04 has the P-K SO stmcture in which distorted tetrahedral TiO ions occur. 

BaAn" 03 (An = Th Am) all have the perovskite strueture and are obtained from the aetinide dioxide. In aeeord with normal redox behaviour, the Pa and U eompounds are only obtainable if O2 is rigorously exeluded, and the Am eompound if O2 is present. Aetinide dioxides also yield an extensive series of nonstoiehiometrie, mixed oxide phases in whieh a seeond oxide is ineorporated into the fluorite lattiee of the An02. The UO2/PUO2 system, for example, is of great importanee in the fuel of fast-breeder reaetors. 

C. Determination of mixtures of selenium and tellurium Procedure. Dissolve the mixed oxides (not exceeding 0.25 g of each) in 100 mL of concentrated hydrochloric acid, and add with constant stirring 50 mL cool concentrated hydrochloric acid which has been saturated with sulphur dioxide at the ordinary temperature. Allow the solution to stand until the red selenium has settled, filter through a weighed filtering crucible (sintered-glass or porcelain) and complete... 

So long as a compound has a fairly intense absorption which is unlikely to overlap with those of other substances with which it is likely to be mixed, then it is possible to monitor that substance on a continuous basis with a dedicated infrared detector. Gases such as carbon dioxide, nitrogen oxides, ethylene oxide and ammonia can now be measured and regulated using these devices. 

The flame ionization detector Is the most popular of the flame-based detectors. Apart from a reduction in sensitivity compared to expectations based on gas chromatographic response factors [138] and incompatibility with the high flow rates of conventional bore columns (4-5 mm I. 0.), the flame ionization detector is every bit as easy to use in SFC as it is in gas chromatography [148,149]. It shows virtually no response to carbon dioxide, nitrous oxide and sulfur hexafluoride mobile phases but is generally incompatible with other mobile phases and mixed mobile phases containing organic modifiers except for water and formic acid, other gas chromatographic detectors that have been used in SFC include the thermionic ionization detector (148,150], ... 

Energetics are size-reduced and mixed with concentrated nitric acid and silver nitrate to form a slurry. The slurry is mixed with Ag2+ from the electrochemical cells to oxidize the energetic material, forming carbon dioxide, nitrogen oxides, water, inorganic salts, and carbon monoxide. 

Local association of the reduced cation and the oxygen vacancy is clearly suggested by the thermodynamics of the hypo-stoichiometric mixed oxides (Ui yPUy)02 x, where the thermodynamic functions do not depend on x and y separately, but rather on a quantity, called plutonium valence , which contains the ratio x/ y73,87) Q sters consisting of this association have been proposed in order to explain the thermodynamics of actinide hypostoichiometric dioxides. 

Other reported syntheses include the Reimer-Tiemann reaction, in which carbon tetrachloride is condensed with phenol in the presence of potassium hydroxide. A mixture of the ortho- and para-isomers is obtained the para-isomer predominates. -Hydroxybenzoic acid can be synthesized from phenol, carbon monoxide, and an alkali carbonate (52). It can also be obtained by heating alkali salts of -cresol at high temperatures (260—270°C) over metallic oxides, eg, lead dioxide, manganese dioxide, iron oxide, or copper oxide, or with mixed alkali and a copper catalyst (53). Heating potassium salicylate at 240°C for 1—1.5 h results in a 70—80% yield of -hydroxybenzoic acid (54). When the dipotassium salt of salicylic acid is heated in an atmosphere of carbon dioxide, an almost complete conversion to -hydroxybenzoic acid results. They>-aminobenzoic acid can be converted to the diazo acid with nitrous acid followed by hydrolysis. Finally, the sulfo- and halogenobenzoic acids can be fused with alkali. 

Christie et al. (45) and Pendleton and Taylor (46) have recently reported the results of propylene oxidation over bismuth molybdate and mixed oxides of tin and antimony and of uranium and antimony in the presence of gas-phase oxygen-18. Their work indicated that for each catalyst, the lattice was the only direct source of the oxygen in acrolein and that lattice and/or gas-phase oxygen is used in carbon dioxide formation. The oxygen anion mobility appeared to be greater in the bismuth molybdate catalyst than in the other two. 

Sulfur dioxide is produced by burning either sulfur or a sulfide such as pyrite in the furnace. The dioxide is then mixed with the catalyst, NO, which may be prepared in either of two ways. In the older method, nitric acid vapor is formed in the niter pot, and when this vapor comes into contact with sulfur dioxide, nitric oxide is formed in accordance with the following equation ... 

Nitric acid Nitrogen dioxide mixed with nitrogen oxide, oxygen, nitrogen Nitrous oxides Nitric acid, water Nitric acid manufacture Stripping not practiced... 

Mixed Oxides.—In some cases so-called mixed acidic oxides are known which combine with water, producing a mixture of two acids nitrogen tetroxide is an example of this class, as also is chlorine dioxide—... 

CAMERE [CArbon dioxide hydrogenation to form MEthanol via a REverse water-gas shift reaction] A process developed in Korea in the 1990s. The preferred catalyst is a mixed oxide of Cu-Zn-Zr-Ga. 

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