Phase control of upconversion nanocrystals and new rare earth fluorides though a diffusion-controlled strategy in a hydrothermal system.
Here we report a general hydrothermal technology to obtain well-known rare earth fluorides involving β-NaYF(4):Yb, Er/Tm and β-NaGdF(4):Yb, Er/Tm upconversion nanocrystals, one new polymorph of γ-REF(3) (RE = Eu-Tm, Y) and hexagonal LiREF(4) (RE = Nd-Lu, Y) colloidal nanocrystals.