Cobalt oxygen flux

A number of metals, such as copper, cobalt and h on, form a number of oxide layers during oxidation in air. Providing that interfacial thermodynamic equilibrium exists at the boundaries between the various oxide layers, the relative thicknesses of the oxides will depend on die relative diffusion coefficients of the mobile species as well as the oxygen potential gradients across each oxide layer. The flux of ions and electrons is given by Einstein s mobility equation for each diffusing species in each layer... 

In 2004, void formation in spherical samples was rediscovered at the nanolevel and discussed in [4-6]. HoUow nanosheUs of cobalt and iron oxides and sulfides have been obtained by means of reaction of metaUic nanopowders with oxygen or sulfur. Contrary to [2, 3], these results have been explained by the Frenkel effect - out-diffusion of metal through the formation of a spherical layer of the compound is faster than in-diffusion of oxygen or sulfur through the same phase. This inequahty of fluxes generates the inward flux of vacancies, meeting inside and forming the void in the internal part of the system. 

The synthesis of Co-doped LiCOyNii y02 was initially affected by solid-state reaction. A fluxing agent and an oxygen atmosphere are necessary to obtain high-performance materials when the preparation temperature is less than 800°C. If there is no oxygen atmosphere, LiCOyNii 2 will partially decompose into Li20 when the temperature is above 800°C. To obtain a solid solution of pure LiCOyNii y02 phase when 0.7 < y < 0.9, the preparation temperature should be raised to 1000°C. As a result, the value of y in LiCOyNii y02 is often less than 0.3. When the doping amount of cobalt is <0.2, extra Ni + will appear, and Li-deficient products are prepared. When y > 0.3, solid solutions with a pure 2-D structure can be obtained. 

The liquid membranes of cobalt—Schiff s base complexes could produce oxygen from air at purities significantly higher than those of present-day polymeric or passive liquid membranes. The liquid membrane produced more than 80% oxygen at a product flux of 3-4 cm cm " h under certain conditions. The oxygen/nitrogen selectivity was 26 and P02 was 2.6 X 10 cm (STP) cm cm s cm Hg [36]. 

Although the liquid membranes containing the cobalt complexes as a mobile carrier for facilitated oxygen transport could provide an elegant method for improving both the selectivity and flux of oxygen, the unresolved issues still remain (1) low diffusivity of the carrier, (2) chemical instability of the... 

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