Silicon impurities

The red cake can be further purified by dissolving it in an aqueous solution of Na2C02- The iron, aluminum, and silicon impurities precipitate from the solution upon pH adjustment. Ammonium metavanadate then precipitates upon the addition of NH Cl and is calcined to give vanadium pentoxide of greater than 99.8% purity. 

Fig. 4.5. Schematic of top left corner of the "silicon-impurity" phase diagram. To make things simple, we assume that the liquidus and solidus lines ore straight. The impurity concentration in the solid is then always less than that in the liquid by the factor k (called the distribution coefficient).

Uchino and Azuma [504] developed and proposed a two-step calcination process of tantalum and niobium hydroxides to obtain oxides. The first treatment is recommended to be performed at 500-700°C, and the second- at 750-1000°C. It is reported that the above method ensures the production of oxides that contain only negligible concentrations of fluorine and silicon impurities. 

Equilibrium segregation coefficients, for silicon impurities, 22 493t Equilibrium stages, calculation of, 10 756-759... 

The promoter zinc seems to act rather as a moderator than as a real accelerator of the reaction. It enables a suificient stationarity of the catalytic activity. It seems that the promoter prevents an overall attack of the reaction on the whole of the silicon surface, catalyzed by silicon impurities, which otherwise would lead to a general blockage of the surface by copper species. Possibly, the promoter is able to bind catalyzing impurities. In this way, the active Cu-Si surface species mentioned above can continuously be formed by lateral diffusion of copper species onto still free silicon surface. 

The hydrogen impurity is found to be inversely related to the hydrogen concentration in the reaction gas mixture. Silicon impurities are detected in octahedral holes of the diamond lattice, 1 and may give rise to an 80-fold... 

The oscillatory kinetics of CO oxidation over Pt single crystals has been studied at atmospheric pressure by Yeates et al. (95). They present a model to explain rate oscillations that relies on the oscillatory formation of surface platinum oxide, which was observed in postreaction analysis and was related to the presence of silicon impurity. 

When molten pig iron is poured into molds of a desired shape (engine blocks, brake drums, transmission housings), it is called cast iron. However, pig iron and cast iron contain too much carbon and other impurities for most uses. The structurally stronger material known as steel is obtained by removing the phosphorus, sulfur, and silicon impurities and decreasing the carbon content. 

Na24 iSii36 II Na4Si4 Products of decomposition of DTAC/ AICI3 ionic liquid Nitrogen atmosphere, 24 h at 210-240 °C crystalline silicon impurity phase [89]... 

Processes develop S5Tnbiotic relationships when one provides a produet or service utilized in another. An example of such a relationship is that between steel making and the proeess for the production of oxygen required in the basic oxygen proeess by which carbon and silicon impurities are oxidized from molten iron to produee steel. The long lifetimes and widespread applicability of popular processes make their design for environment of utmost importance. 

Floquet and Dufour (1983) studied the NiO lll surface. It was ( X /3)R30° reconstructed, and was likely to be stabilized by silicon impurities. Warren and Thiel (1994) grew it as a thin film on a nickel substrate. Rohr et al. (1994) found that the p(2 x 2) reconstruction on the bare NiO(lll) surface is destoyed under hydroxylation of the surface. The p(2 x 2) reconstruction was also observed by Ventrice et al. (1994) and described as due to the formation of micro-pyramids, a geometry predicted by Wolf (1992) to lead to a larger stabilization. 

Also, the disilicate La2Si207 has been shown to be a proton conductor, although modest [62]. This may play a role in oxides with silicon impurities, where this phase may form in the grain boundaries [63]. 

Kinch, M. A. (1971). Compensated silicone-impurity conduction bolometer. Journal of Applied Physics, 42, 5861-3. 

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