Efficient green upconversion luminescence in highly crystallized ultratransparent nano-glass ceramics containing isotropic KY3F10 nanocrystals

Abstract

Yb³⁺/Er³⁺ co-doped nano-glass ceramics (GCs) containing isotropic KY₃F₁₀ nanocrystals (NCs) are obtained from a simple ternary oxyfluoride glass by controlled crystallization. The nano-GCs thus obtained, albeit having very large crystallinity of ∼35%, are ultratransparent in the whole visible-light wavelength region of 300-700 nm. Remarkably enhanced green upconversion luminescence (UCL) of Er³⁺ (by 55 times) is observed in the nano-GCs as compared to the precursor glass. Absolute quantum efficiency of the green UCL reaches as high as 0.41±0.02% in the GCs under 10 W/cm² power density. The UCL efficiency is comparable to that of the famous ZBLAN: Yb³⁺/Er³⁺ glass and GCs containing β-NaYF₄:Yb³⁺/Er³⁺ NCs, and nearly twice as large as that of GCs containing KYF₄:Yb³⁺/Er³⁺ NCs under the same excitation conditions.