Visable and ultraviolet upconversion luminescences of Y2O3:Yb3+,Tm3+ nanomaterials

The Y2O3:Yb3+,Tm3+ nanomaterials are prepared by a combustion method. The sample is excited by 980 nm, thereby producing a bright blue emission transition peak (476 nm and 487 nm) and a weak red emission peak(about 650 nm) that can be clearly observed. More important two ultraviolet emission peaks 1I6→3H6 (~297 nm) and 1D2→3H6 (~363 nm) are found. In addition, the change of upconversion emission intensity dependent on the Yb3+ concentrations was recorded and the possible eauses are discussed. Finally, the pump energy dependences of the emission intensity are investigated. The results show that blue and red emissions originate from a three-photon process and ultraviolet emission peak (363 nm) takes its source at a four-photon process.