Density of oxides

The uniformity of film thickness is dependent upon temperature and pressure. The nucleation rate rises with pressure, such that at pressures above atmospheric the high rate of nucleation can lead to comparatively uniform oxide films, while increase in temperature reduces the density of oxide nuclei, and results in non-uniformity. Subsequently, lateral growth of nuclei over the surface is faster than the rate of thickening until uniform coverage is attained, when the consolidated film grows as a continuous layer ... 

Figure 6. pH dependence of (a) current density (on log scale) of oxygen ion incorporation into the oxide, at a constant total current density of 0.1 mA/cm2, and (b) the steady-state dissolution (aluminum ion) current density of oxide-covered aluminum at 4 V versus SCE.29... 

Jensen, G. M., D. B. Goodlin, and S. W. Bunte. 1996. Density Functional and MP2 Calculations of Spin Densities of Oxidized 3-Methylindole Models for Tryptophan Radicals. J. Phys. Chem. 100, 954. 

The density of oxidized states is obtained by changing the signs of the electronic energy e and the overpotential r/ ... 

Fig. 8-13. Electron transfer via the conduction band and hole transfer via the valence band >ox (Dveo) = state density of oxidant (reductant) particles x - distance from an interface i ( ) = anodic (cathodic) current in (ip) = electron (hole) current.

The atmosphere is also important in sintering. Gas trapped in closed pores will limit pore shrinkage unless the gas is soluble in the grain boundary and can diffuse from the pore. Alumina doped with MgO can be sintered to essentially zero porosity in hydrogen or oxygen atmospheres, which are soluble, but not in air, which contains insoluble nitrogen. The density of oxides sintered in air is commonly less than 98% and often only 92-96%. The sintering atmosphere is also important in that it may influence the sublimation or the stoichiometry of the principal particles or dopants. 

The simultaneous movement of ionic and electronic charge carriers under the driving force of a gradient in the electrochemical potential of oxygen facilitates transport of oxygen in the oxide bulk. The flux density of oxide anions is given (Figure 8.12) [77-79,109] by the ambipolar diffusion equation (see Section 5.7.6) [110,111]... 

Oxide Density of Oxide (g/cm ) Glass Formation range of Binary Silicate System (mol % SiOj)... 

The surface number density of oxide ions in the BS model is about 2.1 times less than that for the carbon surface in Fig. 1. However, the diameters of the overlapping spheres over which the probe sphere rolls are larger for the carbon surface in Fig. 1 than for the oxide surface. Thus one expects that the lower of the surfaces in Fig. 1 should be smoother than the upper one. However, this is not the case. The reason why the amorphous carbon surface seems to be rougher than the amorphous oxide surface lies... 

The purpose of calculating Henry s Law constants is usually to determine the parameters of the adsorption potential. This was the approach in Ref. [17], where the Henry s Law constant was calculated for a spherically symmetric model of CH4 molecules in a model microporous (specific surface area ca. 800 m /g) silica gel. The porous structure of this silica was taken to be the interstitial space between spherical particles (diameter ca. 2.7 nm ) arranged in two different ways as an equilibrium system that had the structure of a hard sphere fluid, and as a cluster consisting of spheres in contact. The atomic structure of the silica spheres was also modeled in two ways as a continuous medium (CM) and as an amorphous oxide (AO). The CM model considered each microsphere of silica gel to be a continuous density of oxide ions. The interaction of an adsorbed atom with such a sphere was then calculated by integration over the volume of the sphere. The CM model was also employed in Refs. [36] where an analytic expression for the atom - microsphere potential was obtained. In Ref. [37], the Henry s Law constants for spherically symmetric atoms in the CM model of silica gel were calculated for different temperatures and compared with the experimental data for Ar and CH4. This made it possible to determine the well-depth parameter of the LJ-potential e for the adsorbed atom - oxygen ion. This proved to be 339 K for CH4 and 305 K for Ar [37]. On the other hand, the summation over ions in the more realistic AO model yielded efk = 184A" for the CH4 - oxide ion LJ-potential [17]. Thus, the value of e for the CH4 - oxide ion interaction for a continuous model of the adsorbent is 1.8 times larger than for the atomic model. 

Figure 4.4 Density of oxide ions along (100), (110) and (111) directions in <5-Bi203.

Figure 4.5 Density of oxide ions in (200) and (110) planes of

FIGURE 5.17 Power spectral densities of oxide thickness deviation after CMP. 

For the electrode reaction Eq. (6.1) equations for the partial current densities of oxidation and reduction can be derived by formulating the potential dependence of the rate constants. The now generally accepted formulation goes back to work of Erdey-Gruz and Vohner and Butler. ... 

Otherwise, the transfer of an electron from the metal into the electrolyte can occur, if the electron on an energy level E in the metal finds an unoccupied energy level at the same energy E in the electrolyte. The intensity of electron transfer is proportional to the density of unoccupied electron-energy levels in the metal, times the density of unoccupied energy levels in the electrolyte (the density of oxidized ions,... 

Fiber bums (density of oxidized fiber too low, ingress of air, or insufficient cooling at furnace outlet). Broken tows must be pulled back out of the furnace and spliced on to adjacent tows. 

Figure 17.4 The effect of moisture on the measured density of oxidized fiber. moisture regain=0.04.

Figure 6b. Schottky plot of data on the steady-state ionic current obtained by different experimenters and brought to the same basis of thickness determination. The smooth lines are calculated from the expression fitted to Young s data (Figure 6a). The dots are experimental data due to Vermilyea," (numerical data supplied by Vermilyea) converted by factor allowing for estimated density of oxide (7.93 X 0.99/8.74). The crosses are preliminary unpublished data obtained by Zobel and converted to the refractive index quoted in Young.[For final version, see Young and Zobel, J. Electrochem. Soc. 113 (1966) 277.]...

AU experiments vntcr r lected. Density of oxide or metal fuel In f/cc. ... 

Pu M utt Pu, 25 wtt Pu, 15 wtt itical dimenskms for unmoderated systems at theoretical density of oxides values given for 3 to 15 wt% Pu that have been shown to have the> minimum critical dimensions for those Pu contents lRef. 3). 

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