Oxidized layer profiling

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. 

Figure 27. Types of anion concentration profiles in anodic oxide layers on aluminum, from the O/S interface (O) inwards to the M/O interface (L). LA front of anion penetration.

Figure 25.3 The reaction zone configuration used in the present analysis. On the left side solid lines for T, T02, and YcH.4 represent the outer solution, and the dashed lines show profiles resulting from finite reaction rates in the oxygen-consumption layer. The right side corresponds to an expanded view of the regions around in the left sketch, represented by a single fine there, showing the structure of the radical-equilibrium and fuel-consumption layers A — location of fuel and radical layers, B — oxidation layer, C — radical-equilibration layer, and D — fuel-consumption layer...

Figure 9.10 Depth profile for a non-conducting chromium oxide layer on chromium based alloy measured by rf CDMS. (A. I. Saprykin, J. S. Becker et ai, Fresenius /. Anal. Chem., 358, 145 (1997). Reproduced by permission of Springer Science and Business Media.)...

Depth profiles of matrix elements on Mn- and Co-perovskite layers of fuel cathodes have been measured by LA-ICP-MS in comparison to other well established surface analytical techniques (e.g., SEM-EDX).118 On perovskite layers at a spatial resolution of 100p.m a depth resolution of 100-200 nm was obtained by LA-ICP-MS. The advantages of LA-ICP-MS in comparison to other surface analytical techniques (such as XPS, AES, SIMS, SNMS, GD-OES, GDMS and SEM-EDX) are the speed, flexibility and relatively low detection limits with an easy calibration procedure. In addition, thick oxide layers can be analyzed directly and no charging effects are observed in the analysis of non-conducting thick layers. 

Fig. 7. Schematic representation of charged cation interstitial (ci) and anion interstitial (ai) bulk concentration profiles within the oxide, leading to defect currents of cation and anion interstitials and subsequent chemical reaction leading to a continual increase in oxide layer thickness, L, with time, t.

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