Facile synthesis of ultrasmall hexagonal NaYF4:Yb3+,Er3+ upconversion nanocrystals through temperature oscillation

Abstract

Ultrasmall (10.8 nm) and uniform hexagonal NaYF₄:Yb³⁺,Er³⁺ upconversion nanocrystals have been successfully synthesized through a temperature oscillation technique, and the nucleation and growth processes of nanocrystals were effectively separated and controlled by simply regulating the heating procedures.