Tantalum oxide electrodes

A. Baraka, A.J. Abdel-Rohman and E.A. El-Taher, The Use of Tantalum/Tantalum Oxide Electrode as an Indicator Electrode in Potentiometric Acid-Base Titration in Fused Potassium Nitrate, Mater. Chem. Phys. 9 (1983) 447-456. 

An English patent (1906) describes the production of pure tantalum by electrolysis of fused K2TaF7 in a refractory crucible of magnesium oxide or tantalum oxide, using pure tantalum metal as cathode and the impure metal as anode. A French patent (1907) claims that very pure tantalum may be prepared by electrolysis of tantalum material in a 3 per cent solution of H2SO4. The electrodes are platinum or carbon and a current of 0.1-0.3 ampere at two volts is required. 

Schematic representation of a metal-arch capacitance transducer according to Jones et al. [245]. This capacitance transducer is of the variable-area electrode type. A tantalum/tantalum oxide film structure is deposited onto a flat glass substrate to obtain a suitably flat surface for contact with a flexible electrode which may be a thin metal foil possibly deposited in the shape of a dome or an arch...

A membrane filter which can be dissolved in acetone, or a spectrochemically pure graphite filter which can be examined directly with a powder DC-arc technique, can provide passable results. After air has been drawn through a previously weighed filter, the membrane filter is dissolved in acetone, then centrifuged. The particulates are collected, dried, and weighed then a spectroscopic buffer is added composed of 1 part NaF and 1 part graphite powder, with 100 ppm indium oxide and 20,000 ppm tantalum oxide as internal standards. About 35 mg of the final mixture is placed in a graphite electrode and arced at 15 A for 60 sec in a controlled (90% At-10% O2) atmosphere. 

Bianchi, G. De Nora, V. Gallone, P. Nidola, A. (1971) Titanium or tantalum base electrodes with applied titanium or tantalum oxide face actiwited with noble metals or noble metal oxides. US Patent 3,616,445 October 26,1971. 

KCl-NaCl-K2TaF7 melts On addition of potassium heptafluotantalate to the NaCl-KCl melt a peak of tantalum reduction to metal (Rl) from fluoro-chloro complex (as will be shown below) was observed on voltammograms (Fig. 1). On the anodic part of the curve several peaks of the deposited tantalum oxidation correspond to it. The anodic peaks OJ andOJ" should be referred to tantalum dissolution respectively in the form of Ta(lV) and Ta(V) chloro complexes, formed in the absence of excess fluoride ions. Recording of the cyclic voltammetric curve with a potential reverse at more positive potential -0.48 or -0.6 V (Fig.l), when the amount of tantalum deposited at the electrode is small and there is not enough time for diffusion of a considerable quantity of the liberated fluorine into the melt bulk, shows no such peaks, which corroborates our assumption. Peaks Oi and OJ were caused by tantalum disso-... 

High chlorine production yield and suitable lifetime are achieved with mixed metal oxide electrodes (MMO), initially developed for the chlor-alkali process [4]. They consist of a base metal, a titanium plate, or grid for saltwater chlorination coated with a combination of at least two metal oxides including titanium, ruthenium, iridium, or tantalum [5]. Elaborated proprietary production processes are used to achieve reliable electrodes. The chlorine faradaic yield under typical pool working conditions (3 g/L NaCl, current density 50 mA/cm ) is around 60 % [6]. Good quality electrodes achieve several years of service time (several thousands of hours of continuous operation) with a 3 h reversal time and at 60 % of the nominal maximum power. Lifetime is reduced by high current densities and by frequent polarity reversal. Operation at... 

Lagow, C. H., Sladek, K. J., and Richardson, P. C., 1971, Anodic insulated tantalum oxide electrocardiograph electrodes, Trans. IEEE, BME 18(2) 162-164. 

Masud, X, Alam, M.T., Awaludin, Z., El-Deab, M.S., Okajima, T. Ohsaka, T. Electrocatalytic oxidation of methanol at tantalum oxide-modified Pt electrodes. J. Power Sources 220 (2012), pp. 399-404. 

Aluminum foil capacitors occupy an important position in circuit applications due to their unsurpassed volumetric efficiency of capacitance and low cost per unit of capacitance.328 Together with tantalum electrolytic capacitors, they are leaders in the electronic discrete parts market. Large capacitance is provided by the presence of extremely thin oxide layers on anodes and cathodes, and high surface areas of electrodes could be achieved by chemical or electrochemical tunnel etching of aluminum foils. The capacitance of etched eluminum can exceed that of unetched metal by as much as a factor of 50.328... 

The mechanism of cathodic luminescence is distinctly different from other ECL systems. Light is emitted from oxide-covered, so-called valve metal, electrodes, namely aluminium and tantalum, during the reduction of peroxodisulfate, hydrogen peroxide, or oxygen, in aqueous solution, at relatively low potentials (<10 V). The mechanism involving persulfate, for example, is as follows. A conduc-... 

Electrode Potential.—This can be determined only in solutions of fluorides, since tantalum shows valve action in all other electrolytes, and even in the case of fluorides there is some reason to believe that oxide formation takes place, vitiating the results. The potential at the electrode... 

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