Duplex oxide structure

In experiments covering a larger potential region, from the oxidized state until the complete neutral state, a new resonance circuit was found not described by the transmission line model. A new model was suggested by Pickup et al., which was used and modified later by Rammelt and Plieth et This model is corroborated by the duplex film structure (Figure 11.9). A compact layer on the metal/polymer interface with neutral state properties in the neutral state and double-layer properties in the oxidized state describes the compact polymer film the transmission fine model represents the porous part (Figure 11.17). 

Porous or nonporous films can be formed but the porous film is the one most widely used for corrosion protection. Porous oxide films are composed of two layers an outer porous layer of duplex layer structure, and an inner nonporous layer (barrier layer). The main compounds of porous oxide films are amorphous AFO, y-AUO, 7-AI2O3, ci-ALO, and other compounds depending on the electrolyte used. 

Silver is chemically close to copper. Oxide layers can be easily reduced on this seminoble metal and the polarization curve is qualitatively similar. However, there are also many differences for their passive behavior. Figure 5.21 shows the polarization curve in IM NaOH with two pronounced anodic and cathodic peaks [72]. Like in the case of Cu, Ag20 is formed at Al and it is further oxidized to AgO at A2. A duplex film structure is suggested for oxidation at E > 0.73 V (A2) in IM NaOH. 

For oxidation of G in duplex DNA, Steenken concluded that the proton on N-1 of G shifts spontaneously to N-3 of the cytosine in the normal Watson-Crick base pair to generate [C+(H)/G ]. Consistent with this proposal, calculations indicate that charge transfer in oxidized DNA is coupled with proton transfer from G to Experiments carried out in D2O also reveal a kinetic isotope effect for G oxidation, implicating a concerted proton-coupled electron transfer mechanism. However, density functional theory (DFT) calculations in the gas phase predict that the structure with a proton on G N-1 [C/HG ] is more stable than [C (H)/G ] by 1.4kcal/mol. " ... 

Duplex structures often occur in metallic, oxide, salt and other binary and multicomponent systems. W.J. Tomlinson and A. Easterlow290... 

Note that the duplex structure of the layer of a chemical compound, observed in the quasibinary systems formed by the oxides or salts with a common ion, may be of somewhat different nature, frequently being simply a result of different crystallographic orientation of the grains of initial phases. A suitable example is the process of formation of the NiAl204 spinel between the NiO and A1203 oxide phases, studied in detail by D.W. Su-snitzky et al. 

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