Gd2O3:Dy3+ nanocrystals were synthesized via solvothermal method followed by a subsequent calcination.The samples were characterized by X-ray diffraction(XRD),transmission electron microsopy(TEM),Electronic dispersive X-ray spectroscopy(EDX),photoluminescence(PL)spectrum and decay curves.The effect of the annealing temperature on the crystallinity and particle size was studied;heat treatment improved the crystallinity of as-prepared nanocrystals as well as increased their particle size.The nanocryatals presented monodispersed spherical shape under TEM.Photoluminescence spectra showed that nanocrystal exhibited strong yellow emission corresponding to 4F9/2→6H13/2 transition(573 nm)of Dy3+ under UV light excitation,which broadened with the particle size decreased without structure changed.The theoretical mechanism of luminescence was explored and surface effect was thought to be the main reason. Gd2O3: Dy3 + nanocrystals were synthesized via solvothermal method followed by a subsequent calcination.The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Electronic dispersive X-ray spectroscopy and decay curves. The effect of the annealing temperature on the crystallinity and particle size was studied; heat treatment improved the crystallinity of as-prepared nanocrystals as well as increased particle size. The nanocryatals presented monodispersed spherical shape under TEM. Photoluminescence spectra saw that which broadened with the particle size decreased without structure changed. The theoretical mechanism of luminescence was explored and surface effect was thought to be the main reason.