Facile ex situ NaF size/morphology tuning strategy for highly monodisperse sub-5 nm β-NaGdF 4 :Yb/Er

We report a facile ex situ NaF size/morphology tuning strategy for NaF release rate regulation and successfully used it to achieve controlled solvothermal synthesis of highly monodisperse sub-5 nm β-NaGdF 4 :Yb/Er. In particular, such a strategy needs neither a long nanocrystal nucleation time nor a low growth temperature, which thus renders the preparation of highly crystalline sub-5 nm β-NaGdF 4 :Yb/Er time-saving at a high reaction temperature of 300 °C.