Facile large-scale synthesis of monodisperse REF3 (RE = Y, Ce, Nd, Sm-Lu) nano/microcrystals and luminescence properties

Abstract

Highly monodisperse YF₃:Ln³⁺ (Ln = Eu, Ce, Tb, Yb/Er, Yb/Ho, and Yb/Tm) nano/microcrystals with controllable size and morphology have been synthesized by an innovative low-temperature (≤0 °C) precipitation route free of any surfactant. Interestingly, the monodispersity and morphology are independent of the pH value and reactant concentration at a low temperature even when the reactant concentrations are close to saturation. This allows for a high yield production at 150 g L⁻¹ of reaction system. A detailed investigation of the growth process reveals that a low temperature can ensure a more definite separation of nucleation and growth. Simultaneously, the low temperature-induced diffusion-controlled growth model gives rise to a size focusing effect, which further insures the monodispersity of the final products. Furthermore, our synthetic strategy can be extended to other lanthanide fluorides (REF₃, RE (rare earth) = Ce, Nd, Sm-Lu), and the obtained YF₃:Ln³⁺ samples exhibit strong down/upconversion emissions. Such a facile synthetic strategy fits well with the green concept in current synthetic innovations for nanocrystals and may provide some guidance in the kinetically controlled synthesis of inorganic nanocrystals.