Inhibiting emission quenching in (Y0.1Yb0.05Er0.005Al)2O3 by Sc3+ co-doping to enhance upconversion luminescence

We report for the first time the synthesis of a co-doping oxide system by introducing Sc3+ to co-doped Al2O3 with Yb3+, Er3+ and Y3+ via sol–gel method. The green and red upconversion (UC) luminescence of the co-doped Al2O3 has been obviously improved with the increasing of the amount of Sc3+. Microstructures of the co-doped Al2O3 with different amounts of Sc3+ have been investigated by XRD, HR-TEM, NMR, XPS and FT-IR to find the role of Sc3+ in this system, and several key changes of the micro–nano-structure have been revealed, which are helpful to inhibit the factors of the quenching of UC luminescence. With the increasing of Sc3+ co-doping concentration, the Er3+ dispersity has been improved, the distance between Er3+ and OH− has been enlarged, amount of OH− absorption has been reduced, the asymmetry of Er3+ local surrounding has been improved, and the carbon impurity has been reduced. As the results, UC luminescence quenching has been inhibited greatly, and the electronic population of transition levels has been enhanced. The luminescence intensity can be enhanced several times and decay time can be extended over five times. This research may be useful for the design and synthesis of high-performance UC co-doping materials.