title: Controlled growth, intense upconversion emissions and concentration induced luminescence switching of bifunctional Tm(3+) doped hexagonal NaYb0.55Gd0.45F4 nanorods.
abstract: Bifunctional hexagonal Tm(3+) doped NaYb0.55Gd0.45F4 nanorods with tunable size are prepared via in situ cation-exchange reaction using hydrothermal method. The measured field dependence of magnetization of the NaYb0.55Gd0.45F4 nanorods shows typical paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of rare-earth ions. When excited by a 980nm laser, these nanorods exhibit intense multi-color up-conversion (UC) emissions in infrared, red, blue and especially ultraviolet. In addition, luminescent switching between different UC emission wavelengths of 480nm and 450nm is observed by adjusting Tm(3+) doping concentration. Based on power-dependent spectral analyses, it is found that with the increase of Tm(3+) doping concentration, due to the suppressed saturation effect, the dominative UC process redistribute the populations at (1)G4 and (1)D2(Tm(3+)) states of Tm(3+) ion resulting in the above luminescent switching. Our results indicate that bifunctional hexagonal NaYb1-xGdxF4 nanocrystals have potential applications in miniaturized solid-state light sources, optical processing sensors and fluorescent biolabels.
authors.affiliation: School of Computer and Communication, Hunan Institute of Engineering, Xiangtan, China. quxilong@126.com
authors.forename: Xilong
authors.initials: X
authors.lastname: Qu
authors.forename: Yongchang
authors.initials: Y
authors.lastname: Li
authors.forename: Suixi
authors.initials: S
authors.lastname: Yu
authors.forename: Liwen
authors.initials: L
authors.lastname: Yang
mesh_terms: D003460:Crystallization; D005682:Gadolinium / Q000737:chemistry*; D049449:Luminescence; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D013696:Temperature; D013932:Thulium / Q000737:chemistry*; D014961:X-Ray Diffraction; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D013932:Thulium; D005682:Gadolinium; D015018:Ytterbium
keywords: Bifunctional; Luminescent switching; Nanorods; Up-conversion