Synthesis and up-conversion white light emission of RE~(3+)-doped lutetium oxide nanocubes as a single compound

摘要

Uniform and dispersive Lu_2O_3:Yb~(3+)/Er~(3+)/Tm~(3+) nanocubes have been successfully synthesized by hydrothermal process with subsequent calcination at 900 "C. The as-formed RE~(3+)-doped lutetium oxide precursor via the hydrothermal process, as a template, could transform to RE~(3+)-doped LU_2O_3 with their original cubic morphology and slight shrinkage in the size after post-annealing process. The formation mechanism for the lutetium oxide precursor cubes has been proposed. Under single wavelength diode laser excitation of 980 nm, the as-obtained Lu_2O_3:3%Yb~(3+)/0.5%Er~(3+)/0.3%Tm~(3+) nanocubes show nearly equal intensities of blue (Tm~(3+): 1~G_4→3~H_6), green (Er~(3+): (2~H_(11/2), 4~S3/2)→4~I_(15/2)), and red (Er~(3+): 4~F_(9/2)→ 4~I_(15/2)) emissions, which produces bright white light emission, clearly visible to the naked eyes. The main pathways to populate the upper emitting states come from the energy-transfer processes from Yb~(3+) to Tm~(3+)/Er~(3+), respectively. The chromaticity coordinate oftheLu_2O_3:3%Yb~(3+)/0.5%Er~(3+)/0.3%Tm~(3+)sample is calculated to be about x - 0.3403 and y = 0.3169, which falls exactly within the white region of 1931 C1E diagram and is very close to the standard equal energy white light illuminate (x = 0.33 and y = 0.33), pointing out its potential use as a white light source under 980 nm laser diode excitation.