Tuning into single-band red upconversion luminescence in Yb3+/Ho3+ activated nano-glass-ceramics through Ce3+ doping

摘要

Yb3+/Ho3+ activated glass ceramics containing beta-YF3 nanocrystals were successfully fabricated. The green (S-5(2)/F-5(4) -> I-5(8)) upconversion emission is dominant in the glass ceramics and is about 160 times stronger than that of the precursor glass, resulting from the partition of lanthanide activators into a low-phonon-energy crystalline lattice and the subsequent low probability of multi-phonon nonradiative relaxation from the S-5(2)/F-5(4) and I-5(6) states to the lower ones. Upon the introduction of Ce3+ ions into nano-glass-ceramics, two efficient cross-relaxation processes between Ho3+ and Ce3+, i.e., Ho3+:S-2/F-5(4) + Ce3+:F-2(5/2) -> Ho3+:F-5(5) + Ce3+:F-2(7/2) and Ho3+:I-5(6) + Ce3+:F-2(5/2) -> Ho3+:I-5(7) + Ce3+: F-2(7/2), are demonstrated to greatly suppress the population of the green-emitting S-5(2)/F-5(4) state and to enhance the population of the red-emitting F-5(5) one, leading to the intense single-band red UC radiation of Ho3+.