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

Abstract

Yb³⁺/Ho³⁺ activated glass ceramics containing β-YF₃ nanocrystals were successfully fabricated. The green (⁵S₂/⁵F₄→⁵I₈) 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 ⁵S₂/⁵F₄ and ⁵I₆ 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⁺:⁵S₂/⁵F₄ + Ce³⁺:²F_5/2→Ho³⁺:⁵F₅ + Ce³⁺:²F_7/2 and Ho³⁺:⁵I₆ + Ce³⁺:²F_5/2→Ho³⁺:⁵I₇ + Ce³⁺:²F_7/2, are demonstrated to greatly suppress the population of the green-emitting ⁵S₂/⁵F₄ state and to enhance the population of the red-emitting ⁵F₅ one, leading to the intense single-band red UC radiation of Ho³⁺.