New Insights into the Influence of the 4f(5)5d(1) State in the 4f(6) Electronic Configuration of Sm2+ in Crystal Hosts

摘要

The use of the Sm2+ luminescence properties in numerous applications appeals for a better understanding of its electronic structure. This work compares luminescence data and crystal field parameters from 31 Sm2+-containing compounds to assess the effects of the crystal field on its energy levels. In particular, the relationship between the D-5(0)-F-7(0), and D-5(0)-F-7(1) transition energies is analyzed and compared with previously published data for the isoelectronic Eu3+. It appears that for Sm2+, in contrast to Eu3+, the energy of the D-5(0) state cannot be considered to be constant and implies the involvement of an extra state (presumably the 4f(5)5d(1) level) in the mixing of the 4f(5) states. On the other side, the total crystal field strength is correlated to the splitting of the F-7(1) states for both Sm2+ and Eu3+ in lower symmetry environments. The plot of the D-5(0)-F-7(0) energy as a function of the F-7(1) splitting clearly evidences the mixing of the 4f(6) state with the environment-sensitive 4f(5)5d(1) state for Sm2+, which is finally confirmed by the discrepancy of the ratio between the D-5(1) and F-7(1) splittings from its theoretical value in the absence of any mixing with the 4f(5)5d(1) state.