Thallium, electrodeposition

Van den Bossche, B., Floridor, G., Deconinck, J., Van Den Wmkel, P. Hubin, A. (2002). Steady-state and pulsed current multi-ion simulations for a thallium electrodeposition process. Journal of Electroanalytical Chemistry 531(1) 61-70. 

In the ex situ studies, the thallium layer was electrodeposited and the electrode was subsequently removed from solution and placed inside a helium-filled box where the XSW experiments were carried out. 

Bhattacharya, R. N. Feldmann, M. Larbalestier, D. Blaugher, R. D. 2001. Electrodeposition process for the preparation of superconducting thallium oxide films. IEEE Trans. Appl. Supercond. 11 3102-3105. 

The electrodeposition of thallium on Ag(l 10) is similar to that which takes place on the (111) face of silver [122]. The voltammogram shows well-defined structure in the formation of the first monolayer, and further deposition occurs before formation of the bulk deposit. Fig. 5.16c and d display the results for the isotropic and anisotropic response respectively. The magnitude and phase of o 2 were modeled by a constant contribution from the adatoms throughout the adsorption process (Eq. (5.4)). Values of x /Xin = 0-94 and a phase shift of 131° were obtained. As with Ag(lll), an enhancement in the anisotropic response was observed beyond 1 monolayer and was attributed to a similar resonance effect. 

Metallic thallium, Tl, can be electrodeposited in a basic EMICI-AICI3 ionic liquid [25]. It is possible to dissolve thallium trichloride, TICI3, to form a trivalent thallium chlorocomplex anion, TlClg , which is reducible to a monovalent thallium chlorocomplex anion, TlCl ... 

T vo different approaches have been made to increase the maximum deposition rate which is reached under a given set of deposition conditions. The first approach involves addition of a depolarizer, such as lead or thallium ions [162-164]. These ions are known to adsorb strongly on gold and to bring about underpotential deposition (UPD) during electrodeposition of gold [165]. The depolarization effect amounts to as much as 0.2 V, as reported by Matsuoka et al. [164] and illustrated in Fig. 34. These authors show that addition of such depolarizers to a borohydride bath increases the deposition rate by a factor of as much as 8 to 10 (Fig. 35). 

Not only compositions containing all the HTSC metal components, but also simpler subsets, may be considered as the precursors. Thus, by a combined technique [189], Ba-Ca-Cu films were obtained by electrodeposition and then thallium was introduced from the vapor phase in the course of simultaneous oxidation. In [190, 191], it was shown that reproducible preparation of Bi-Pb cuprates can be achieved when three-component precursors are deposited and the alkaline earth cations are then introduced before annealing. It is practically impossible to provide reproducible deposition of five-component precursors. Two-stage electrosynthesis of HBCCO [200] included the intermediate annealing of a Ba-Ca-Cu deposit followed by mercury electrodeposition on the resulting oxide substrate. 

In conclusion, we note that deposition of submono- and monolayers of adatoms is the most controllable and reliably predictable method of obtaining metallic nanodimension compositions. At least two or three kinds of adatoms can be deposited in a strictly layer-by-layer fashion on single-crystal substrates [217], and mixed adlayers can also be obtained. The combined deposition of adatoms and phase deposits of metals [217] is even more promising. Among the metals, HTSC components such as lead, thallium, bismuth, and copper rank among the most thoroughly studied adatomic systems. Electrodeposition methods are also applied to the technological preparation of conventional superconductors based on Nb-Sn alloys [218]. 

In the most sensitive eiectroanaiytical methods, exclusively treated within this context, the analyte ion is electrodeposited on an electrode from an electrically conducting sample solution. Current and potential of subsequent redissolution are due to the concentration and the kind of ion to be determined. For thallium, the reversible redox couple TI /TI° at about -0.5 V versus saturated calomel electrode is used (Bellavance and Miller, 1975). Infinite tolerance towards alkali, alkaline earths and halogenides are great merits for the analysis of biological materials. Because of the preconcentration step included, thallium determination is more sensitive than atomic spectrometric methods. For thallium, the multielement capabilities of the method can hardly be used, because lead and frequently cadmium have to be masked with excess of complexants, leaving just Tl in the potential... 

Belous AN (1978) Studies on the electrode processes at the electrodeposition of thallium, lead and tin liom sulphide and sulphide-chloride melts. PhD (Kandidate) Thesis, Institute of General and Inorganic Chemistry, Kiev... 

In addition to these direct NP oxidation detection experiments, the underpotential deposition (UPD) of metal ions from solution onto metal NPs during collisions between the NPs and an inert electrode was also reported (see Figure 8.18). Reactions for UPD of thallium and bulk electrodeposition of cadmium onto Ag NPs were used for detection, which formed bimetallic core-shell NPs (denoted Ag Tl and Ag Cd, respectively). For the case of thallium, it was shown that up to a... 

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