Pure red upconversion photoluminescence and paramagnetic properties of Gd2O3:Yb3+, Er3+ nanotubes prepared via a facile hydrothermal process

The cubic Gd 2 O 3 :20% Yb 3+ , 2% Er 3+ nanotubes have been synthesized via a facile hydrothermal method and subsequently calcination. Field emission scanning electron microscopy images show that as-obtained Gd 2 O 3 entirely consists of uniform nanotubes with outermost diameters of ~ 250 nm and lengths of ~ 2 μm. The corresponding Gd 2 O 3 :20% Yb 3+ , 2% Er 3+ nanotubes exhibit completely paramagnetism and the magnetic mass susceptibility of them is about 0.28 × 10 − 4 emu g − 1 Oe − 1 at 300 K. Pure red light ranged from 645 nm to 685 nm in the nanotubes was observed and assigned to the 4 F 9/2 → 4 I 15/2 transition of Er 3+ under excitation of 980 nm undergoing an upconversion and the emission intensity was found to decrease in applied magnetic field.