Luminescence and radiative decay of Er³⁺ in Cs₂NaErCl₆

Abstract

The 488 nm- and 514 nm-argon-ion excited luminescence spectra of Cs₂NaErCl₆ and Cs₂NaGdCl₆ : ErCl^3- ₆ have been recorded between 10-295 K in the spectral range 26 030-3640 cm^-1 and the ⁴ I _11/2 → ⁴ I _15/2, ⁴ I _13/2; ⁴ I _9/2 → ⁴ I _15/2; ⁴ F _9/2 → ⁴ I _15/2, ⁴ I _11/2; ⁴ S _3/2 → ⁴ I _15/2, ⁴ I _13/2, ⁴ I _11/2, ⁴ I _9/2; ² H _11/2 → ⁴ I _15/2, ⁴ I _13/2; ⁴ F _7/2 → ⁴ I _13/2; ² G _9/2 → ⁴ I _15/2, ⁴ I _11/2, ⁴ F _9/2; and ⁴ G _11/2 → ⁴ I _15/2 transitions are assigned and interpreted in detail. Magnetic-dipole sponaneous emission probabilities have been calculated for the six lowest excited terms of Er³⁺ in Cs₂NaErCl₆ and some values vary by a factor of up to five between 10-295 K. Total radiative decay rates for multiplet-multiplet transitions have been obtained for ⁴ S _3/2 and lower terms, by integration of the emission spectra, and since the values are very similar to the measured decay rates the multiphonon relaxation rates are very slow for these terms of Er³⁺ in cubic elpasolite hosts.