Wydział Chemii

Weichang Li

Jixi Xu

Qiang He

Yan Sun

Shiyu Sun

Wei Chen

Małgorzata Guzik

Georges Boulon

Lili Hu

2020

Journal of Alloys and Compounds

845

155820/1-155820/10

10.1016/j.jallcom.2020.155820

Naukowa

Angielski

Artykuł

The development of novel phosphors with stable and efficient green and red up-conversion (UC) emission is important for many applications such as fluorescent labeling, color display and anticounterfeiting. In this work, we report a stable and efficient green and red up-converter of LiYF₄:Yb³⁺,Ho³⁺ octahedrons obtained by modified hydrothermal method. The UC emission and luminescence decays of LiYF₄:Yb³⁺,Ho³⁺ with various Yb³⁺ and Ho³⁺ ion concentrations were studied systematically under 976 nm LD excitation. The Yb³⁺ and Ho³⁺ ion concentrations were optimized to be 20 mol% and 1 mol% respectively, for efficient green and red UC emissions. LiYF₄:Yb³⁺,Ho³⁺ presents not only controlled morphology of monodisperse octahedrons with length of ∼20 μm and width of ∼10 μm, but also performs efficient green and red UC emissions, which is about four times stronger than that of β-NaGdF₄: 20 Yb³⁺,0.5Ho³⁺ (NaGdF₄: 20 Yb³⁺,0.5Ho³⁺). More importantly, the stable UC emission with variation of green intensity ratio ΔG% (G% = I_520-570nm/I_500-700nm, ΔG%= (G%)_max-(G%)_min) and red intensity ratio ΔR% (R% = I_625-685nm/I_500-700nm, ΔR%= (R%)_max-(R%)_min) < 1% was found over 976 nm LD excitation power density (PD) ranging from 1.0 to 5.6 W/cm². Whereas, their variations of ∼6% and 25% are observed at the same excitation PD for NaGdF₄:20 Yb³⁺,0.5Ho³⁺ and commercial β-NaYF₄:20 Yb³⁺,2Er³⁺ (NaYF₄: 20 Yb³⁺,2Er³⁺), respectively. The mechanism of green and red UC emissions in LiYF₄: Yb³⁺,Ho³⁺ as a consequence of energy transfer processes has been briefly discussed taking into account the UC emission kinetics. The highly stable intensity ratio of G% and R% combined with the efficient green UC color hints the potential application of LiYF₄: Yb³⁺,Ho³⁺ in fluorescent labeling and color display.

Stable green and red up-conversion, Micro-octahedrons, Fluorescent labeling

http://dx.doi.org/10.1016/j.jallcom.2020.155820

http://www.elsevier.com