Investigation of the effects of cerium concentration and overpotential on the morphology and purity of uranium dendrites

The applied overpotential (25 mV, 50, mV, 100 mV, 200 mV) and uranium to cerium mass ratios (1:0, 1:1, 2:1) in a LiCl–KCl molten salt eutectic were varied to observe their effects on the morphology and purity of uranium during potentiostatic electrodeposition. In general, rhomboidal-platelet type crystals were observed at lower overpotentials and dendritic, “tree-like” crystals were observed at higher overpotentials; in addition, a decrease in overall crystal size with increasing overpotential was observed. The addition of cerium to the melt achieves similar morphologies as that of the higher overpotential conditions without cerium present for all overpotentials explored. Compositional analysis techniques (e.g., scanning electron microscopy with energy dispersive x-ray spectroscopy, x-ray diffraction, inductively coupled plasma mass spectrometry) suggest that co-deposition is not present in the uranium electrodeposits; however, minimal presence of cerium found are likely due to salt occlusion and/or poor washing technique of the harvested uranium product. The results of this study provide additional evidence the uranium electrodeposit morphology varies with the presence of impurities in the melt.