Temperature dependence of fluorescence for EuCl3 in LiCl–KCl eutectic melt

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

“…The peak positions of the europium fluorescence were found to be almost independent of the temperature [11]. However, after changing the electrolyte (matrix) from LiCl-KCl to LiCl in this study, the observed Eu 2+ fluorescence changes ( Fig.…”

“…The melts were located in a specially manufactured quartz cell, in which an original rectangular quartz fluorescence cell was attached to a long neck quartz tube, which was placed at the center of the electric furnace. Details of the manufactured furnace and arrangements of the spectroscopic components were described previously in the figures in [10,11].…”

“…Na + (0.99 Å)] and Eu 2+ (1.12 Å) ions, which makes the possible substitution of lithium by the europium ions in the melt inappropriate' [2]. In the meantime, the same amount (in wt.%) of EuCl 3 in the LiCl-KCl produced transparent fluidic molten salt without any aggregation or precipitation [11]. The formation of small clusters, large aggregates, and metastable and stable second-phase precipitates was produced, due to the migration of impurity ions through the alkali halide matrix, which occurred easily due to a nearby compensating cation vacancy [13].…”

“…The excitation (at 337 nm) with light lying within the absorption band produced only one fluorescence band, whose peak position is located in the blue region of the electromagnetic spectrum with the melt of EuCl 3 and LiCl. The reduction% of Eu 3+ at high temperature is dependent on the concentration of Eu 3+ mixed in the matrix, but when almost the same amounts (24.33 mM EuCl 3 ) of EuCl 3 were in LiCl-KCl molten salts [11] and LiCl molten salts, the reduction% of Eu 2+ from starting Eu 3+ was higher in LiCl, based on a relative comparison of fluorescence-peak intensities from both fused salts. Europium in the LiCl melt is considered as existing in a divalent state, and Eu 3+ can only be present in minor amounts.…”

Optical absorption and fluorescence properties of trivalent lanthanide chlorides in high temperature molten LiCl–KCl eutectic

“…3, fluorescence spectra of Eu(II) and Dy(III) were measured at 500°C, and Tb(III) was obtained at 540°C. Recently, several groups have measured the fluorescence spectrum of Eu(II) in LiCl-KCl eutectic at various temperatures [38,61,69], whereas the fluorescence spectrum of Eu(III) has not been observed in high-temperature LiCl-KCl eutectic. The fluorescence properties of Eu(III), Eu(II), Tb(III), and Dy(III) were reported in our previous studies in detail [4,22,41].…”