Preparation, growth mechanism and upconversion and near infrared photoluminescence properties of convex-lens like NaYF4 microcrystals doped with various rare earth ions excited at 808 nm

Preparation of rare earth ions doped photoluminescence materials with controlled morphology was desired to fulfill the requirement of different applications. In the work, the convex-lens like NaYF4 microcrystals doped with various rare earth ions were prepared by adjusting preparation parameters including the reaction time, reaction temperature, NaOH concentration, ratio of oleic acid to 1-octadecene and types of doping ions. Possible growth mechanism of convex-lens like NaYF4 microcrystals is proposed based on reaction time and temperature dependent morphology evolution. The formation of micro convex-lens includes the three processes of NaYF4 nanoparticles self-assemble, dissolution–nucleation and regrowth. Doping-ions dependent near infrared and upconversion luminescence properties of convex-lens like NaYF4 microcrystals were investigated excited at the 808 nm. The visible upconversion luminescence was observed in the Er3+, Yb3+/Er3+, Nd3+/Er3+, Nd3+/Yb3+/Er3+ doped convex-lens like NaYF4 microcrystals,...