The enhanced upconversion fluorescence and almost unchanged particle size of β-NaYF4:Yb3+, Er3+ nanoparticles by codoping with K+ ions

• Published in: Journal of alloys and compounds Vol. 610; pp. 432 - 437
• Main Authors: Liang, Zhiqin, Cui, Yue, Zhao, Suling, Tian, Lijiao, Zhang, Junjie, Xu, Zheng
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.10.2014; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Er3+ nanocrystals; Exact sciences and technology; K+ ions; Nanocrystals and nanoparticles; NaYF4:Yb3; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Upconversion fluorescence; Er3+ nanocrystals; K+ ions; NaYF4:Yb3; Upconversion fluorescence; Particle size; Impurity density; NaYF; nanocrystals; Fluorescence; Frequency conversion; Yb; Crystal field; K; Er; Luminescence decay; Nanoparticles; Energy-level transitions; Potassium additions; Ytterbium additions; Rate equation; ions; Microstructure; Erbium additions; Codoping; Nanocrystal; Sodium Yttrium Fluorides Mixed
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.04.183

•There are no significant changes in morphology and size with K+ ions codoping.•The UC intensity are enhanced a lot with K+ ions codoping.•The synthesized nanoparticles contribute to improve immune chromatography test. In this work, the improved upconversion (UC) intensity, the same morphology and almost unchanged particle size of β-NaYF4:Yb3+, Er3+ via codoping with low content K+ ions is reported. Hexagonal NaYF4 nanoparticles with a spherical morphology are synthesized by introducing 0–15mol% K+ ions. The morphology of the nanoparticles changed to a hexagonal plate-like shape when the K+ ion concentration continuously increased to 20mol% or more. The UC fluorescence intensities of the green and red emissions of Er3+ are gradually improved and reached a maximum when the concentration of K+ ions was 15mol%. The decay lifetimes of 4S3/2 and 4F9/2 were determined. The enhancement in UC intensity was mainly ascribed to tailoring the local crystal field around Er3+ ions. Furthermore, we tested the optimized concentration by monitoring the decay lifetime of the intermediate 4I11/2 state followed by theoretical steady-state rate equations.