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Structural destruction quenching of down- and upconversion emission in CaF2:Yb3+, Tb3+

We observed an unusual luminescent phenomenon of Yb3+ in CaF2:Yb3+, Tb3+. Upon excitation at 380 nm, the downconversion luminescence of Yb3+ ions exhibited a monotonic decreasing trend with the increase of Tb3+ concentration from 0.025 mol% to 1 mol%, which implied a unique quenching mechanism. Its inverse process, the cooperatively sensitized luminescence of Tb3+ ions showed that the upconversion emission also quenched at a low concentration (0.075 mol%) of Tb3+ ions. To explain the above emission quenching phenomenon, we further performed the optically inactive rare earth ion doping experiment and fluorescence dynamic measurements. Finally, we found that the cluster structural destruction quenching mechanism dominated the quench of the down- and upconversion emissions induced by cooperative transitions in CaF2: Yb3+, Tb3+.