Down conversion luminescence of Tb3+–Yb3+ codoped SrF2 precipitated glass ceramics

In the Tb3+–Yb3+ codoped glass ceramics with SrF2 nanocrystals precipitated, the energy transfer mechanism from Tb3+ to Yb3+ was investigated. The excitation power dependence of emission intensity study showed that the quantum cutting occurs during the energy transfer from Tb3+ to Yb3+ with the excitation of Tb3+ high energy level. However, the one-photon process is the main reason that is responsible for the Yb3+ infrared emission. The external quantum yields of Tb3+ and Yb3+ were evaluated by using an integrating sphere measurement system with the excitation of 377 and 488 nm lasers, which are much lower than the expected quantum efficiencies calculated from Tb3+ lifetimes. The external quantum yields in the glass ceramics and as-made glasses were also compared.