Spectroscopic Studies of Neodymium(III) and Praseodymium(III) Compounds in Molten Chlorides

A novel spectroscopic furnace has been developed for the in situ acquisition of UV-visible absorption spectra in high temperature molten salts. The furnace has been used to obtain spectra of neodymium(III) and praseodymium(III) trichloride in LiCl-KCl eutectic at 450°C over various Ln(III) concentrations. The major absorption peaks for both for Nd(III) and Pr(III) in the UV-visible region of the spectrum have been identified and the molar absorbances quantified for each of these absorption maxima. The neodymium and praseodymium were then precipitated by adding respectively, Li₂CO₃ and Li₂O to the salt and monitored using UV-visible spectroscopy. In both cases the precipitate has been identified as the relevant LnOCl by powder XRD.