Luminescence spectroscopy and near-infrared to visible upconversion in Er3+ and Yb3+ codoped Sc2O3 nanoparticles

Abstract The Er 3+ and Yb 3+ co-doped Sc 2 O 3 nanoparticles were prepared by co-precipitation method. The phase structure and up-conversion properties were investigated using XRD, FESEM and up-conversion spectra. The nanoparticles with the size of about 40 nm emitted red and green light. Yb 3+ ions are crucial to adjust the intensity proportion of red and green emission as a sensitizer. In Er 3+ , Yb 3+ co-doping samples, the red emissions are much higher than green and the intensity ratio is up to 56.43, while the green to red intensity ratio is 11.21 with Er 3+ single doping, which both show excellent mono-chromaticity. Strong red emissions are attributed to the cross-relaxation energy transfer and energy back-transfer processes. High Yb 3+ ions concentrations induce the red up-conversion saturation, resulting in a near linear laser power dependence, and it can be illustrated based on steady-state rate equations.