A novel synthetic route towards monodisperse β-NaYF4:Ln(3+) micro/nanocrystals from layered rare-earth hydroxides at ultra low temperature.

Monodisperse β-NaYF4:Ln(3+) (Ln = Yb/Er, Yb/Tm) single micro/nanocrystals were first one-pot fabricated at 50 °C through a novel synthetic route containing two pivotal processes: (a) synthesis of a β-NaYF4 {0001} unit layer through a novel style of ion-exchange from Y2(OH)5NO3·nH2O (LYH) and (b) the subsequent oriented-assembly process.