Spectroscopic analysis of trivalent cerium and holmium ions in LiCl–KCl eutectic melt at high temperature

The chemical behavior of trivalent cerium (Ce3+) and holmium (Ho3+) dissolved in a LiCl–KCl eutectic melt was investigated through a spectroscopic analysis. The molten LiCl–KCl bath was constructed using an externally controlled high-temperature furnace apparatus. Ultraviolet–visible absorption and fluorescence spectra were recorded at 400 °C. We observed heavily broadened and intense fluorescence spectra of Ce3+ attributed to the electric-dipole-allowed 5d–4f transition. The fluorescence signal of Ho3+ separately dissolved in the LiCl–KCl eutectic was difficult to detect in the visible range. The fluorescence emission of Ho3+ containing various intra-f transitions in the visible range was strongly enhanced when Ho3+ and Ce3+ ions were co-dissolved in a LiCl–KCl eutectic melt. - Highlights: ► Fluorescence of Ho3+ and Ce3+ mixtures in a KCl–LiCl melt was examined with pulsed laser excitation. ► Broad fluorescence emission band of Ce3+ appeared in the absence of Ho3+ with 355-nm excitation. ► There appeared no prominent emission peaks from Ho3+ in the absence of Ce3+. ► Fluorescence of Ho3+ ions was strongly enhanced in the presence of Ce3+ by energy transfer.