Synthesis and upconversion luminescence properties study of NaYbF4:Tm3+ crystals with different dopant concentration

Tm3+ ion doped α-NaYbF4 nanocrystals (NCs) and β-NaYbF4 microcrystals (MCs) were prepared by one-step hydrothermal method through tuning pH values. Through the comparative study on the crystal growth mechanism guided by two different organic additives, the effect of Na+ cation on morphologies was discussed. Under 980-nm excitation, intense ultraviolet (UV) and blue upconversion (UC) emissions were observed from both of them. The UC luminescence properties of the as-prepared MCs were studied based on changing the Tm3+ ion concentrations. The fluorescent lifetimes of MCs doped with different amount of Tm3+ ions indicate that the obtained NaYbF4:Tm3+ MC was an excellent matrix for UV UC emissions.