Electrochemical and spectroscopic investigations of Tb(III) in molten LiCl–KCl eutectic at high temperature

Electrochemical and spectroscopic properties of Tb(III) in molten LiCl–KCl eutectic at high temperature were investigated by cyclic voltammetry and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The diffusion coefficient of Tb(III) and the formal standard potential of Tb(III)/Tb0 were determined to be 2.06 ± 0.4 × 10− 5 cm2 s− 1 and − 2.83 ± 0.03 V vs. Cl2/Cl− at 887 K, respectively. Additionally, visible fluorescence of Tb(III) due to the electronic transitions from 5D3 and 5D4 to 7FJ was observed and measured by TRLFS for the first time. These results provide the first fluorescence spectroscopic evidence for a direct in situ quantification of Tb(III) in the high temperature molten salt system.