Preparation and characterization of upconversion nanocomposite for β-NaYF 4:Yb 3+,Er 3+-supported TiO 2 nanobelts

Abstract

Hexagonal NaYF 4:Yb 3+,Er 3+ (β-NaYF 4:Yb 3+,Er 3+) nanoparticles supported on TiO 2 nanobelts were prepared using two-step procedures of ion-exchangeable process and hydrothermal treatment: layered titanate nanobelts were first ion-exchanged with Y 3+, Yb 3+ and Er 3+ cations to produce titanate nanobelts with these cations, and then, the product nanobelts in NaY solution were treated under hydrothermal condition to transform into anatase TiO 2 nanobelts supported with β-NaYF 4:Yb 3+,Er 3+ nanoparticles. The final products were characterized by various measurement techniques. Many preparation conditions, e.g., the content of added precursors, reaction time and pH value, were optimized to obtain nanocomposites including relatively uniform nanoparticles with strong upconversion (UC) emission intensity. The measurement results showed that the anatase TiO 2 nanobelts, supported by the large number of β-NaYF 4:Yb 3+,Er 3+ nanoparticles with 30-70 diameter range and very strong UC emission, could be achieved under suitable preparation condition. The UC emission intensity of the nanoparticles with the concentrations of Yb 3+ and Er 3+ closer to 20 mol.% and 1 mol.% was the strongest.