Lanthanide activator doped NaYb1−xGdxF4 nanocrystals with tunable down-, up-conversion luminescence and paramagnetic properties

Novel NaYb1−xGdxF4 (0 ≤ x ≤ 1) nanocrystals were synthesized by a modified liquid–solid–solution solvothermal route for the first time. X-ray diffraction analyses and transmission electron microscope observations evidenced that the phase, size and shape of NaYb1−xGdxF4nanocrystals were closely related to the Gd3+ content. Particularly, when the Gd3+ content reached 60 mol%, the final products were highly uniform and monodisperse hexagonal NaYb0.4Gd0.6F4nanorods. By doping appropriate lanthanide activators, these nanorods exhibited efficient dual-sensitizing multicolor emissions, i.e., Gd3+ sensitizing down-conversion by an ultraviolet light excitation orYb3+ sensitizing up-conversion by a near-infrared one. The lanthanide activator doped NaYb0.4Gd0.6F4nanorods with tunable up-conversion luminescence and proper paramagnetism originating from Gd3+ ions may find potential applications in bio-probes and magnetic resonance imaging.