Procedure, electrodeposition

Trautmann [100] obtained better than 90% electrodeposition of Cf-nitrate from a 5-mL isopropanol solution containing 100 gL of 0.1 M HNO3. Electrodeposition was performed at 1000 V for 30 min onto Ti, Ta, and C cathode foils. The electrodeposition procedure can also be performed from an aqueous HCl solution at pH 2.7 with added NH4CI as electrolyte. With an applied potential of 8-12 V and a resulting current density of 1.6-2 A cm , 98% of Cf can be deposited on Ti or Ta cathode foils in 15 min. 

I am grateful to Mr. David Sisson for his work with the electrodeposition procedures and to Mr. Thomas Massey for conducting the final purification chemistries. 

We describe below the electrodeposition procedures required in the preparation of the platinum and silver- silver chloride electrodes used in electrochemical experiments. We shall not attempt to give a general treatment of electroplating or of electrode preparation. Further details can be found in various monographs. ... 

Procedure 20. Determination of Pu in Urine (Small Area Electrodeposition Procedure) B. W. Perkins (Ref. 316)... 

Note 2 The mixed Th/ Th planchet is worthless after the decay of Th. A useful standardization can be made with a planchet with 60dpmU electrodeposited on it (evaporate a weighed aliquot in a small Teflon beaker and follow electrodeposition procedure of Th Section 13.7.7). After ingrowth of Th to secular equilibrium with (several months), the planchet can be used for a check on the relative efficiencies of beta and alpha counters. Alpha detector efficiency determined this way for should also be applicable to but an independent calibration of the °Th spike is still required. 

In the case of ionic liquids containing high amounts of halides, the chemical attack of the metallic oxides at the electrode surface occurs that means that only few metals are really inert in these media and consequently the anodic potential limit is governed rather by the metal oxidation. Even metals such as R, Au, A1 and Ti may be oxidized in ionic liquids and their oxides can be dissolved especially in eutectics containing chloride ions as ligands for metallic ions dissolution. This phenomenon allows the use of soluble anodes during electrodeposition procedure. 

Uranium may be deposited electrolytlcally at the cathode of a cell from acetate,carbonate, 22. oxalate, formate,- 22. phosphate, fluoride,and chloride — solutions. Many of the uranium electrodeposition procedures have been developed In an effort to prepare thin, uniform films for alpha and fission counting rather than to separate the element from any particular Impurity. However, In the work of Smith and co-workers and Coomans uranium was separated from alkali and alkaline earth metals and zinc. Oasto and Rodden and Warf— review much of the material pertinent to the electrodeposition of uranium. 

Toxic substances adsorbed on resins are removed during a regeneration procedure. The resulting spent regeneration solution has a higher concentration of the toxic substance than the stream from which it was removed by the resin. Toxic material in the spent regenerating solution can usually be precipitated, electrodeposited as in an electrolytic ceU, or made insoluble by other acceptable procedures. 

At the start the cathode is invariably a metal different from that to be deposited. Frequently, the aim is to coat a base metal with a more noble one, but it may not be possible to do this in one step. When a metal is immersed in a plating bath it will corrode unless its potential is sufficiently low to suppress its ionisation. Fortunately, a low rate of corrosion is tolerable for a brief initial period. There are cases where even when a cathode is being plated at a high cathodic (nett) current density, the substrate continues to corrode rapidly because the potential (determined by the metal deposited) is too high. No satisfactory coating forms if the substrate dissolves at a high rate concurrently with electrodeposition. This problem can be overcome by one or more of the following procedures ... 

A procedure involving (a) the deposition of nearly stoichiometric films of copper and indium on suitable substrates using vacuum evaporation or electrodeposition and (b) the heat treatment of Cu-In films in a hydrogen-selenium atmosphere at temperatures above 630 °C was reported to yield large grain (several mm in size), stoichiometric thin films of chalcopyrite CIS with a preferred 112 orientation [167]. 

Aqueous cathodic electrodeposition has been shown to offer a low-cost route for the fabrication of large surface n-CdS/p-CdTe solar cells. In a typical procedure, CdTe films, 1-2 xm thick, are electrodeposited from common acidic tellurite bath over a thin window layer of a CdS-coated substrate under potential-controlled conditions. The as-deposited CdTe films are stoichiometric, exhibit strong preferential (111) orientation, and have n-type conductivity (doping density typically... 

McGregor SM, Dharmadasa IM, Wadsworth 1, Care CM (1996) Growth of CdS and CdTe by electrochemical technique for utilisation in thin film solar cells. Opt Mater 6 75-81 Morris GC, Das SK (1992) Some fabrication procedures for electrodeposited CdTe solar cells. Int J Sol Energy 12 95-108... 

Early measurements of " Th were on seawater samples and Th was co-precipitated from 20-30 L of seawater with iron hydroxide (Bhat et al. 1969). This procedure may not recover all of the " Th in the sample, and an alpha emitting Th isotope (e g., °Th or Th) is added as a yield monitor. Following chemical purification of the Th fraction by ion exchange chromatography, the Th is electrodeposited onto platinum or stainless steel planchets. The planchets are then counted in a low background gas-flow beta detector to measure the beta activity and subsequently with a silicon surface barrier detector to determine the alpha activity of the yield monitor. The " Th activity is thus determined as ... 

Measurements of " Th in sediment samples (Aller and Cochran 1976 Cochran and Aller 1979) used much the same approach as outlined above. In this case, the dried sediment sample ( 10 g) was leached with strong mineral acid (HCl) in the presence of a yield monitor (generally Th, an artificial Th isotope resulting from the decay of Th that is produced by neutron capture on Th). Thorium was separated from U and purified by ion exchange chromatography, and electrodeposited onto stainless steel planchets. Counting and determination of " Th activity followed the procedure outlined above. 

In electrogravimetry, also called electrodeposition, an element, e.g., a metal such as copper, is completely precipitated from its ionic solution on an inert cathode, e.g., platinum gauze, via electrolysis and the amount of precipitate is established gravimetrically in the newer and more selective methods one applies slow electrolysis (without stirring) or rapid electrolysis (with stirring), both procedures either with a controlled potential or with a constant current. Often such a method is preceded by an electrolytic separation using a stirred cathodic mercury pool, by means of which elements such as Fe, Ni, Co, Cu, Zn and Cd are quantitatively taken up from an acidic solution whilst other elements remain in solution. 

EC-ALE is the combination of UPD and ALE. Atomic layers of a compound s component elements are deposited at underpotentials in a cycle, to directly form a compound. It is generally a more complex procedure than most of the compound electrodeposition methods described in section 2.4.2, requiring a cycle to form each monolayer of the compound. However, it is layer-by-layer growth, avoiding 3-D nucleation, and offering increased degrees of freedom, atomic level control, and promoting of epitaxy. 

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