Optical spectroscopy and magnetic behaviour of Sm3+ and Eu3+ cations in Li6Eu1-xSmx(BO3)3 solid solution

Abstract A new borate solid solution series of powders, Li 6 Eu 1-x Sm x (BO 3 ) 3 (LSEBx, x = 0.35, 0.5, 0.6, 1), were synthesized by solid-state reaction, characterized and their luminescent properties were investigated. The absorption spectra indicate that absorption takes place mainly from the Sm 3+ 6 H 5/2 ground state, with a strong band at 405 nm. The photoluminescence spectra reveal that the Eu 3+ red emission intensity strongly depends on the Sm 3+ content x. Judd–Ofelt theory was applied to experimental data for the quantitative determination of phenomenological parameters Ωi (i = 2, 4, 6) Judd Ofelt parameters, radiative transition rates and emission quantum efficiency. Owing to the energy transfer from Sm 3+ to Eu 3+ the intense red light detected at 613 nm at room temperature under UV or blue light excitation, was improved by ∼35% as compared with Sm 3+ -free samples. This energy transfer was confirmed by faster decay times of Sm 3+ as energy donors. Moreover, the energy transfer between Sm 3+ and Eu 3+ is unidirectional and irreversible, implying that the energy transfer wastage between Sm 3+ and Eu 3+ is very low. Magnetic susceptibility (χ) measurements of LSEBx were carried out in the temperature range 2–320 K and are used to compare calculated and experimental energy levels.