Electrochemical Reduction of Chromate in the Presence of Nickel Chloride in Molten Lithium Chloride-Potassium Chloride Eutectic

Chronopotentiometry of chromate in the presence of NiCl2 in molten LiCl-KCl eutectic reveals a diffusion controlled, three electron reduction step. In the presence of excess NiCl2, chromate is reduced at −0.35V vs. Pt(II)/Pt reference electrode and the electroactive species responsible for the chrono-potentiometric wave is estimated to have a diffusion coefficient of 1.06 · 10−5 cm2 sec−1 at 450°C. The stoichiometry of the reduction product depends mainly on the temperature at which the deposit is formed. At 500°C the deposit approaches the composition LiNi2CrO4. X-ray powder diffraction shows the deposit to be a single compound with a face centered cubic lattice. The length of the unit cell edge is estimated to be 4.14Å. At 1400°C a weight loss of the deposit is observed. X-ray powder diffraction shows the presence of two phases, which are identified as NiO and NiCr2O4 The weight loss is attributed to volatization of Li2O