ZnO: Er3+-Yb3+/Gd2O3 core/shell nanoparticles are synthesized via a seeded deposition process with ZnO: Er3+-Yb3+ nanoparticles as seeds and Gd2O3 as shells, respectively. Analyses on phase and structures indicate that the Gd2O3 shell is around 1 nm in thickness. Raman signals change with the increase of Gd2O3 shell deposition times, which are the synergistic results of phonon confinement effect and interface strain. Visible up-conversion (UC) emissions are observed in the seed samples, after Gd2O3 surface modification, great enhancement of the UC emissions are observed. The detail is discussed. (C) 2013 Elsevier B.V. All rights reserved.