One-pot solvothermal synthesis of singly doped Eu3+ and codoped Er3+, Yb3+ heavy rare earth oxysulfide Y2O2S nano-aggregates and their luminescence study

Highly crystallized micro/nano-sized Y2O2S and RE (Eu3+, Yb3+/Er3+) doped samples were prepared through a one-pot mild (200–250 °C) solvothermal method. By simply adjusting the amount of initial sulfur powder, the morphology and assembled nano-structures could be well controlled. With varying concentration of sulfur powder from 0.08 M to 0.8 M, the morphology and size of the target products varied from 20 nm nanosheets, 2 μm sheet-assembled plates/flowers to 1.5 μm nano-assembled spheres. The luminescence properties of Eu3+ doped Y2O2S with different morphologies were studied. The excitation peak above 300 nm ascribed to S2−–Eu3+ charge transfer showed a blue shift of 9 nm compared with the bulk sample. When co-doped with Yb3+/Er3+, the Y2O2S:Yb3+, Er3+ nano-aggregates exhibited a tunable emission under 980 nm laser excitation, shifting from greenish-yellow to orange-yellow, with increasing Yb3+/Er3+ ratio.