Enhanced Near-Infrared Upconversion Emission of Yb3+-Tm3+ Co-doped Gd2O3 Sub-microrods

Lanthanide-doped rare-earth oxides have aroused great interest in display and bio-probe technology due to their excellent luminescent and magnetic performance. In this paper, Gd2O3 sub-microrods (SMRs) with cubic structure are obtained via heat-treatment from gadolinium hydroxides precursor. Upconversion (UC) spectra show intense near-infrared (NIR) emission which is assigned to 3H4 → 3H6 transition of Tm3+. From the double logarithmic plot of emission intensity versus pump powers, it was seen that typical two photons were involved in the NIR UC process. Moreover, a series of Gd2O3:18%Yb3+,x%Tm3+ (x = 0.1, 0.5, 1, 2, 5) and Gd2O3:y%Yb3+,0.5%Tm3+ (y = 1, 5, 10, 40, 80) SMRs were prepared and characterized to explore their NIR emission properties. Finally, the enhanced NIR emission property was found in Gd2O3:Yb3+,Tm3+ SMRs from the reduced NaOH concentration and the reduced calcinations temperatures.