Oxide depth profiles

M. F. Toney and S. Brennan. Structural Depth Profiling of Iron Oxide Thin Films using Grazing Incidence Asymmetric Bra X-ray DiflFraction. J. Appl. Phys. 65J 4763, 1989. 

Fig. 2.9. Depth profiles ofthin (3-5-nm) oxide films [2.10] on (A) pure iron, (B) Fe-12Cr-l Mo alloy.

A multilayer-type structure probably due to cords in the molten zone between single arc sprayed (0.25 MPa) Ni droplets and steel substrate were found in AES point depth profiles [2.158]. That particular arc spraying condition turned out to yield the best adhesion. Plasma-sprayed AI2O3 layers separated from pre-oxidized Ni Substrate had a micrometer-thick NiO layer on the substrate-sided face and micrometer-deep oxide interdiffusion [2.159]. In this work also, AES point depth profiling substantiated technological assumptions about adhesion mechanisms. 

Fig. 3.39. HF-plasma SNMS sputter depth profiles (DBM) ofTi-48AI-2Cr (atom%) samples having been oxidized at 800 °C in air for (a) less than 4 s,...

Fig. 4.35. GIAB depth profiling of yttrium ion-implanted NiCr that had been oxidized in air for 8 min at 700 °C. A = alloy substrate, C = Cr203,...

In order to carry out depth profiling with AES, the sputtering rate must be determined. The sputtering rate is usually measured by determining the time required to sputter through a layer of known thickness. Anodized tantalum foils are convenient for this purpose since the oxide thickness can easily be controlled and since the interface between the metal and the oxide is relatively sharp [43]. 

Fig. 40. Auger depth profile of an as-prepared oxide obtained by anodizing 2024 aluminum alloy in phosphoric acid. Reproduced by permission of Chapman and Hall Ltd. from Ref. [38].

According to the depth profile of lithium passivated in LiAsF6 / dimethoxyethane (DME), the SEI has a bilayer structure containing lithium methoxide, LiOH, Li20, and LiF [21]. The oxide-hydroxide layer is close to the lithium surface and there are solvent-reduction species in the outer part of the film. The thickness of the surface film formed on lithium freshly immersed in LiAsF /DME solutions is of the order of 100 A. 

Fig. 21—AES depth profiles of the TiN coatings (a and b) and the TiN/Si3N4 coating with optimum Si content of 10.8 at. % and hardness of 47.1 GPa (c and d) annealed at the temperature of 600 or 800°C in ambient atmosphere. The oxidation depth of the coatings is the sputtering depth where the oxygen atomic percentage reaches the minimum level.

Figure 3. Ti" " SIMS depth profile of 30 X Pt on oxidized Ti(OOOl)...

XPS is very useful for the study of surface layers and corrosion films. In the case of corrosion films and oxides it is important to do depth profiling by coupling XPS with ion milling of the surface. Another important aspect of XPS is that the incident X-rays cause negligible damage to the surface. 

The electron interaction between nanosized gold particles and iron oxide support is only one factor which determines the properties of the gold/oxide system. For instance, in the Au/FeO,c/Si02/Si(l 0 0) model sample the depth profile (after successive Ar ion bombardment at a... 

CPAA may be employed to determine trace element concentrations in bulk solid material, but its importance in our present context is that it permits the characterization of a thin surface layer, i.e. the mass of the analyte element per surface unit, with a good detection limit and outstanding accuracy. For example the composition of a surface layer (or foil) of known thickness can be determined, or, conversely, the thickness of a surface layer of known concentration. Depth profiling or scanning is not possible, and a disadvantage of the method is that heating occurs during irradiation. It is also not possible to discriminate between different oxidation states of the analyte element or between different compounds. 

The depth profiling technique used on samples with a barrier film before and after the addition of chloride to the buffering borate electrolyte showed no indication of either chloride penetration or significant reduction of the average oxide layer thickness.123 This, of course, does not rule out the possibility of the formation, by any of the mechanisms suggested above, of pinholes with radii much smaller than that of the ion-gun beam, through which the entire active dissolution could take place, or the possibility that the beam missed pits formed sporadically across the surface. If pinholes which are not visible were formed, the dissolution should proceed in them with extremely high true current densities. 

Imaging chemiluminescence technique. Chemiluminescence analysis is suitable for studying the early stages of the thermal oxidation of rubbers. A weak emission of light formed by chemical reactions appears during the oxidative degradation of hydrocarbons. This technique can be used to depth profile the oxidation of rubbers. MR... 

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