Peculiar temperature-dependent fluorescence of EuCl3 in LiCl molten salt as a result of phase changes

Abstract Fluorescence spectra were obtained in situ as a function of temperature (ranging from room temperature to 956 K) from a melt of EuCl 3 and LiCl. Three different characteristic Eu 2+ fluorescence bands, associated with phase changes, were observed. The critical fluorescence dependence on temperature appearing in the blue fluorescence were resulted from the radiative relaxation from 4f 6 5d 1 excited state to 4f 7 ( 8 S 7/2 ) ground state of Eu 2+ , which was reduced from Eu 3+ of EuCl 3 at high temperature. The fluorescence studies could provide information regarding the phase changes estimated as the stable dihalide, aggregation, and precipitation states of Eu 2+ in alkali halide not only crystallic but also fluidic melting matrix.