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.