Bismuth oxide films

Kang and Rhee grew bismuth oxide films at 225-425 °C by direct liquid injection MOCVD, using Bi(thd)3 dissolved in n-BuOAc. Temperatures above 325 °C tend to decrease the growth rate due to gas-phase dissociation processes. Annealing at temperatures up to 650 °C is necessary to obtain monoclinic o -Bi203. Temperatures above 750 °C convert a-Bi203 into cubic bismuth silicate due to the reaction with the silicon substrate. 

Cathodic deposition of bismuth(in) telluride films has been reported [224] also on copper and nickel foils, from aqueous nitric acid solutions of bismuth oxide and tellurium oxide in molar ratios of Bi Te = 3 3 and 4 3, at 298 K. The... 

Bismuth nitrate together with sodium sulphide and tellurium oxide have been used to grow bismuth chalcogenide films.162-166 The stoichiometric ratio 2 3 has been confirmed by XPS, EDX, and XRD.162-166 The Bi2Te3 films were rough and consisted of particles with a diameter of 30-100nm, and electron probe microanalysis showed a worm-like network structure.164-166... 

Figure 11.3 Spectra of Pt and Au films. A, Pt on quartz, 11 Q/D B, Pt on quartz, 20 Q/D C, Au-bismuth oxide on quartz, 2.5 Q/D D, Au-bismuth oxide on quartz, 11 Q/D, E, film of bismuth oxide on quartz. [From Ref. 55, with permission. Copyright 1970 American Chemical Society.]...

A considerable number of organometallic species of arsenic, antimony and bismuth have been detected in the natural environment in different manners. A number of these are nonmethyl compounds which have entered the environment after manufacture and use [e.g. butyltin and phenyltin compounds for antifouling paints on boats, and arsanilic acid (Figure 2, 5) and phenylarsonic acids (Figure 2, 6-8) for animal husbandry]. Only a few methyl compounds are now manufactured and used (e.g. methyltin compounds for oxide film precursors on glass and methylarsenic compounds for desiccants or defoliants). 

Figure 12.9 Photocurrent spectra for anodic oxide films on bismuth. The left-hand spectrum is for the anodic photocurrent and the right-hand spectrum is for the cathodic photocurrent. Note the additional low-energy response due to internal photoemission at the Bi/Bi203 interface. Adapted from Castillo and Peter (1983).

Elemental bismuth is inert in dry air at room temperature, but oxidizes slowly to become covered with a thin film of the oxide, which gives it a beautiful multi-colored luster. Above its melting point, it oxidizes rapidly to form an oxide film. At red heat in air, it bums with a bluish flame to give a yellow fume of bismuth oxide (BiiOj). It can also be attacked by super-heated water vapor to form the yellow oxide. Heating with sulfur produces bismuth sulfide Bi2S3 as a dark brown to grayish black solid. 

Results obtained for the oxide film on bismuth illustrate this approach [29]. The oxide grows by the field-assisted migration of ions and Fig. 12 shows that the forward sweep of a cyclic voltammogram exhibits the plateau currrent characteristic of this mechanism. On the reverse sweep, where the field is insufficient to sustain further film growth, the current falls to zero until the potential is reached at which the film is reduced. The figure also shows the photocurrent observed under the same conditions when the electrode is illuminated. On the forward sweep, the photocurrent rises as the film thickens, but on the reverse sweep it falls and then changes sign before the reduction potential is reached. 

Fig. 14. (a) Plot of absorption data for the anodic oxide film on bismuth illustrating the determination of the band gap of the oxide, (b) Fowler plot of the cathodic photocurrent data below 2.8 eV showing the threshold intercept at 1.4 eV. (Reproduced with permission from ref. 29.) (c) Origin of the low-energy cathodic photocurrent response at oxide-coated electrodes. If the oxide is effectively insulating, the barrier height for photoemission is half the band gap. 

It is clear that the coolant must be purified. While this is not a problem for sodium, in case of lead one should bear in mind presence of permanent oxides in the circuit taking into consideration corrosion activity of lead and necessity of protective oxide films formation on the metal surface. Comparison of heat transfer in tubes with sodium and lead-bismuth described by (6.1) and (6.2) equations is shown in the Table 6.1. 

In order to decrease the overpotential for cysteine oxidation in cysteine-containing peptides, graphite-epoxy resin or carbon paste electrodes with immobilized cobalt phthalocyanine have been employed in HPLC systems [53,87-89]. Glassy carbon electrodes modified with a mixed-valence ruthenium(I V,III) oxide film stabilized by cyano cross-links [61,62], indium ferricyanide [63], or a Prussian blue film [64], and a bismuth(V)-doped lead dioxide Pb02 film on gold [65] have also been used for detection following HPLC separation. In addition, a carbon fiber modified with a nfixed-valence ruthenium(IV,III) oxide film stabilized by cyano cross-links has been used in CE [46]. 

M. (2005) Deposition and characterisation of bismuth oxide thin films./. Eur. Ceram. Soc., 25, 2171-2174. 

Batteries. Many batteries intended for household use contain mercury or mercury compounds. In the form of red mercuric oxide [21908-53-2] mercury is the cathode material in the mercury—cadmium, mercury—indium—bismuth, and mercury—zinc batteries. In all other mercury batteries, the mercury is amalgamated with the zinc [7440-66-6] anode to deter corrosion and inhibit hydrogen build-up that can cause cell mpture and fire. Discarded batteries represent a primary source of mercury for release into the environment. This industry has been under intense pressure to reduce the amounts of mercury in batteries. Although battery sales have increased greatly, the battery industry has aimounced that reduction in mercury content of batteries has been made and further reductions are expected (3). In fact, by 1992, the battery industry had lowered the mercury content of batteries to 0.025 wt % (3). Use of mercury in film pack batteries for instant cameras was reportedly discontinued in 1988 (3). 

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

The best known of the M/Mfiy electrodes that are used for the determination of pH are the Sb/SbjOj electrodes, but metals such as bismuth and arsenic filmed with their respective oxide act in a similar manner. Copper in alkaline solutions appears to behave as a pH-dependent Cu/CujO,... 

Bi-layer angular movement during current flow, 348, 349, 350 Biological processes, mimicked, 425 Bipolaronic bands as a function of oxidation depth, 342 Bipolar iron-selective film, 226 Bismuth... 

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