title: Lanthanide-Doped KLu2F7Nanoparticles with High Upconversion Luminescence Performance: A Comparative Study by Judd-Ofelt Analysis and Energy Transfer Mechanistic Investigation.
abstract: The development, design and the performance evaluation of rare-earth doped host materials is important for further optical investigation and industrial applications. Herein, we successfully fabricate KLu2F7upconversion nanoparticles (UCNPs) through hydrothermal synthesis by controlling the fluorine-to-lanthanide-ion molar ratio. The structural and morphological results show that the samples are orthorhombic-phase hexagonal-prisms UCNPs, with average side length of 80 nm and average thickness of 110 nm. The reaction time dependent crystal growth experiment suggests that the phase transformation is a thermo-dynamical process and the increasing F-/Ln3+ratio favors the formation of the thermo-dynamical stable phase - orthorhombic KLu2F7structure. The upconversion luminescence (UCL) spectra display that the orthorhombic KLu2F7:Yb/Er UCNPs present stronger UCL as much as 280-fold than their cubic counterparts. The UCNPS also display better UCL performance compared with the popular hexagonal-phase NaREF4(RE = Y, Gd). Our mechanistic investigation, including Judd-Ofelt analysis and time decay behaviors, suggests that the lanthanide tetrad clusters structure at sublattice level accounts for the saturated luminescence and highly efficient UCL in KLu2F7:Yb/Er UCNPs. Our research demonstrates that the orthorhombic KLu2F7is a promising host material for UCL and can find potential applications in lasing, photovoltaics and biolabeling techniques.
authors.affiliation: School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, Guangdong, China.
authors.forename: Dekang
authors.initials: D
authors.lastname: Xu
authors.affiliation: School of Physics and Engineering, Sun Yat-sen Univeristy, Guangzhou 510275, Guangdong, China.
authors.forename: Anming
authors.initials: A
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, Guangdong, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yao
authors.affiliation: School of Physics and Engineering, Sun Yat-sen Univeristy, Guangzhou 510275, Guangdong, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Lin
authors.affiliation: School of Physics and Engineering, Sun Yat-sen Univeristy, Guangzhou 510275, Guangdong, China.
authors.forename: Shenghong
authors.initials: S
authors.lastname: Yang
authors.affiliation: School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275, Guangdong, China.|State Key Laboratory of Crystal Material, Shandong University, Jinan 250100, PR China.
authors.forename: Yueli
authors.initials: Y
authors.lastname: Zhang