Electrochemical behaviour of lanthanum fluoride in molten fluoridesMarta Ambrová, Jana Jurišová, and Vladimír Danielik Department of Inorganic Technology, Institute of Inorganic Chemistry, Technology and Materials, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia
E-mail: marta.ambrova@stuba.sk Received: 4 April 2008 Revised: 28 May 2008 Accepted: 10 June 2008 Abstract: The electrochemical behaviour of lanthanum fluoride dissolved in molten lithium fluoride and in eutectic mixture LiF-CaF2 was investigated by cyclic voltammetry and laboratory electrolysis. The cyclic voltammetry experiments were carried out at 900°C and 800°C, respectively, in a graphite crucible (counter electrode). Several types of working electrodes (Mo, W, Ni and Cu) were used. Ni/Ni(II) was used as a reference electrode. Laboratory electrolysis was carried out in the system LiF-CaF2-LaF3 at 800°C in galvanostatic (j c = −0.21 A cm−2) and potentiostatic (E = 0.87 V) regimes. In both cases, nickel served as the cathode and graphite as the anode. It was found that no new separate reduction peak occurred on the molybdenum or tungsten electrodes in the investigated systems. When copper or nickel electrodes were used, new peaks corresponding to the reduction of lanthanum(III) to lanthanum metal appeared. This can be explained by the formation of alloys or intermetallic compounds of lanthanum with copper or nickel. X-ray microanalysis showed that lanthanum was electrodeposited together with calcium under formation of intermetallic compounds with the electrode materials in the galvanostatic regime. In the potentiostatic regime, mainly lanthanum was deposited, which enabled its separation. Keywords: lanthanum fluoride - molten fluorides - cyclic voltammetry - spent nuclear fuel - laboratory electrolysis Full paper is available at www.springerlink.com. DOI: 10.2478/s11696-008-0068-1
Chemical Papers 62 (6) 559–565 (2008) |
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