Potentiometric study of Sm–O compounds formation in the molten LiCl–KCl eutectic at 450 °C. Determination of a E-pO2− stability diagram

Reactions between samarium trichloride and oxide ions were studied in the fused LiCl–KCl eutectic by potentiometric titration, using an yttria-stabilized zirconia electrode. In the experimental conditions used in this work, the titration curves indicate the formation of insoluble samarium oxychloride. Based on these curves, the calculated solubility product is found to be 10−7.54±0.17, in molal scale. Characterization of the precipitated compound by X-ray diffraction analysis corroborated the oxychloride formation.The combination of the solubility product, the previously determined electrochemical properties and, in the cases that experimental data are not available, the thermochemical data, allowed to set up the potential-pO2− stability diagram. This diagram summarises the properties of samarium species in LiCl–KCl at a given temperature and concentration.