Electrochemical Properties and Nucleation Morphology of Yttrium on Tungsten Substrate in Molten Salt

In this work, the diffusion coefficient and electrocrystallization of yttrium in LiCl-KCl eutectic are typically investigated using different electrochemical techniques such as cyclic voltammetry (CV), chronopotentiometry (CP) and chronoamperometry (CA) techniques. At temperature from 673 to 823 K, the diffusion coefficients of two yttrium concentrations (YCl3 = 3.816 × 10−5 and 9.981 × 10−5 mol ml−1) were determined by CP and CV methods in a range from 0.453 \times 10−5 to 8.25 \times 10−5 cm2 s−1. The nucleation of Y electrodeposition is confirmed to be an instantaneous mode regardless the given temperature, over-potential and concentrations. The morphology of yttrium nuclei and growth evolution on a tungsten surface were characterized by the SEM-EDS. Some individual circular regions corresponding to initial Y nucleation sites are firstly observed on the tungsten surface. The subsequent formed Y nuclei were found to migrate toward those circular nucleation sites to extend its growth on the inside and peripheral of the circle. In addition, no distinct dendritic structure for the Y deposition was observed on the W surface.