Speciation of dysprosium in molten LiCl–KCl–CsCl eutectic: An electrochemistry and spectroscopy study

Abstract

Speciation and behavior of dysprosium (III) chloride in the ternary low melting LiCl–KCl–CsCl eutectic was studied by electrochemistry and spectroscopy techniques. Electronic absorption spectra of Dy(III) ions were recorded at 723–1023 K. Prolonged holding of relatively concentrated DyCl3 solutions in the melt resulted in a very subtle decomposition of Dy(III) to Dy(II) chloro-species. Cathodic reduction of Dy(III) ions on inert molybdenum electrode was studied at 623–973 K in the inert atmosphere by transient electrochemical techniques (cyclic and square-wave voltammetry). In dilute solutions the cathodic reduction of Dy(III) ions was irreversible, proceeded in one stage, and was controlled by the charge transfer. The diffusion coefficients of [DyCl6]3- complex ions in fused LiCl–KCl–CsCl eutectic were determined at different temperatures. The apparent standard potential of Dy(III)/Dy couple was determined by the open-circuit potentiometry and the principal thermodynamic properties of dysprosium trichloride in fused solvent were calculated.