Oxide films, grown

Marino GEB, Nascente PAP, Biaggio SR, Rocha-Pilho RG, Bocchi N (2004) XPS characterization of anodic titanium oxide films grown in phosphate buffer solutions. Thin Solid Pilms 468 109-112... 

Burke and coworkers [241] have studied the multilayer oxide films grown on silver in base during repetitive potential cycling. It was shown, on the basis of its reduction behavior, that the type of oxide obtained was dependent on the lower limit of the oxide growth cycles. Using limits of 1.03-2.60 V (SHE) the oxide film was assumed to be predominantly Ag20, while at limits 0.7-2.60 V, oxide deposit was assumed to be AgOH. Both types of silver oxides are assumed to be involved in premolecular oxidation and electrocatalysis at silver in base. 

Many other chapters are concerned with how metal oxide surfaces react chemically with atoms and molecules. Chaps. 6-9 deal with oxide films grown epitaxially on bulk metals or other oxides. The interfacial properties of oxides are where much of their technological, commercial and environmental utility lies, and these fields will be expanding tremendously over the next few years. 

In order to obtain a fundamental understanding of oxide surfaces, well-ordered thin oxide films, grown in ultrahigh vacuum (UHV) under well-controlled (clean) conditions, has turned out to be a successful approach ([8, 17, 38] and references therein). In contrast to many (insulating) bulk oxides, thin oxide films exhibit electrical and thermal conductivity sufficient for the application of surface sensitive imaging (e.g., STM) and spectroscopic methods (e.g., XPS Auger electron spectroscopy, AES and temperature-programmed desorption, TPD). 

Fig. 17.7 (a) STM image (40 nm x40 nm) and LEED pattern, and (b) top and side view structural model of the Nb Oj oxide film grown on Cu AuflOO). The STM image in (a) shows two domains rotated by 90°. The rhombic j3x-j3 R30° nit cell the niobia layer and the (2x7) super structure between oxygen and metal atoms are indicated. Adapted in part from [44] with permission. Copyright (2005) Elsevier... 

For STM and many other surface-science techniques, conductive samples are needed. However, many oxides with perfect stoichiometry are insulators. This problem has been addressed by studying thin oxide films grown on metal singlecrystal substrates. Epitaxial, thin oxide films can be grown for the right choice of metal substrates, which exhibit surfaces with structures similar to those for bulk oxide samples. 

Vahlas C, Davazoglou D, Vamvacas VE, de Parseval P (1997) Thermochemistry and composition of LPC VD silicon oxides films grown from NH3/TEOS mixtures. In Allendorf MD, Bernard C (eds) Proceedings of the 14th international conference on chemical vapor deposition/Jointly held with the Euro CVD-11. Electrochemical Society, Pennington, NJ, ppl 175-1182... 

FTIR has been successfully applied for studying chemical properties of size-selected clusters on oxide surfaces [39,192,244,252]. In these experiments, the clusters were deposited onto thin oxide films grown on a metal single crystal. In this approach, the metal is used as the mirror in the optical setup the oxide films ought to be thinner than the wavelength of the IR radiation. In this way, vibrations of adsorbates on size-selected clusters with densities as low as 0.2% ML could be detected. Mechanistic information of chemical reactions... 

In a study of anodic oxide films grown on titanium [740], photocurrent spectra were converted, yielding photocurrent conversion efficiencies 0 as a function of electrode potential (see Fig. 5.129). 

The oxide film grown in this process has a thickness of 0.5 pm. It is a film of a zinc oxide/hydroxide containing different chromium oxides (CrO(OH), Cr20j, Cr205, CrOj) and zinc chromate (ZnCrO ). The chromate ions are rather mobile. If a zinc layer on a steel substrate gets a scratch somewhere on the zinc, the chromate will diffuse to this scratch and repassivate the surface (the self-healing mechanism). ... 

Schaufuss AG, Nesbitt HW, Kartio I, Laajdehto K, Bancroft GM, Szatgan R (1998) Reactivity of surface chemical states on fractured pyrite. Siuf Sci 411 321-328 Schedel-Niedrig T, Weiss W, Schlogl R (1995) Electronic stracture of ultrathin ordered iron oxide films grown onto Pt (111). Phys Rev B 52 17449-17460... 

Weiss W, Baibieri A, Vanhove MA, Somorjai GA (1993) Surface stmcture determination of an oxide film grown on a foreign substrate Fc304 multilayer on Pt(lll) identified by low energy electron diffraction. Phys Rev Lett 71 1848-1851... 

The criteria of dryness of the molten salt, coupled with anodizing voltage, has been shown to influence significantly the morphology of oxide films grown on pure aluminum, according to a recent fundamental investigation. ... 

Fig. 11. SEM micrograph of cross-sectional structure and TbF-SIMS depth profiling data of tantalum oxide films grown for different times, (a) Close-up of the edge of a partially detached 5 min oxide film, (b) Depth profile of a film grown for 1 min. (c) Depth profile of a film grown for 10 min. (d) Depth profile of a film grown for 20 min. (Reproduced with permission from Ref. 76. Copyright 2008 American Chemical Society.)...

A layer of thick, protective, strongly cohesive oxide film can be formed on zirconium by a patented process developed at TWV. In this process, a zirconium subject is treated in fused sodium cyanide containing 1-3% sodium carbonate, or in a eutectic mixture of sodium and potassium chlorides with 5% sodium carbonate. Treatment is carried out at temperature ranging from 600 to 800°C for up to 50 h. A treatment time of several hours typically is used. The thickness of oxide film formed in the fused salt bath ranges from 20 to 30 gm. This film has greatly improved resistance to abrasion and galling over thick oxide films grown by many other means. 

Multicomponent hydrous oxide films grown on gold in acid solution, L. D. Burke and P. F. Nugent,... 

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