A Comparative Study of Eu 3+ -Doped Sillenites: Bi 12 SiO 20 (BSO) and Bi 12 GeO 20 (BGO).

The spectroscopic properties of Eu 3+ -doped Bi 12 SiO 20 (BSO) were investigated and compared with that of Eu 3+ -doped Bi 12 GeO 20 (BGO). The emission properties and the absorption spectra have been measured at 10 K as well as at 300 K (room temperature). Luminescence was detected due to the direct excitation of the 5 D 0 level of Eu 3+ , as well as through the excitation of the 5 D 1 level. The Judd-Ofelt theoretical framework was used to compute the radiative lifetimes (τ) and the omega parameters (Ω λ ). The electric dipole transition probabilities, asymmetry ratios (R), along with the branching ratios (β) were also determined based on the obtained experimental data. The strongest detected luminescence belongs to the 5 D 0 → 7 F 0 transition observed at 578 nm, similar to the BGO sillenite. Reasons for the major presence of the 5 D 0 → 7 F 0 emission, theoretically forbidden by the Judd-Ofelt Theory, were investigated and compared with that of the BGO sillenite. Obtained results showed that the strong 5 D 0 → 7 F 0 line is also present in Eu:BSO, indicating that this is a feature of the entire sillenite family and not just Eu:BGO.