The up-conversion luminescent properties and silver-modified luminescent enhancement of YVO4:Yb3+, Er3+ NPs.

In this paper, the unique up-conversion luminescence (UCL) properties of as-prepared and annealing YVO(4):Yb(3+), Er(3+) nanoparticles (NPs, ∼100 nm) and the corresponding YVO(4):Yb(3+), Er(3+)@Ag hybrids under 980 nm excitation were systemically studied through power-dependent, temperature-dependent emission spectra and dynamics. It is interesting to determine that the radiative transition rate of (2)H(11/2)/(4)S(3/2)-(4)I(15/2) for Er(3+) ions in YVO(4) is about an order of magnitude faster than that in the other hosts due to the wave function coupling with the 3d orbital of V(5+) and, thus, the up-conversion (UC) green emissions of YVO(4):Yb(3+), Er(3+) NPs is efficient. In addition, efficient novel UC broad band centering around 630 nm (1.97 eV) was observed in YVO(4):Yb(3+), Er(3+) powders, which was attributed to defect emissions related to oxygen vacancies near V(5+) sites in the lattices of YVO(4). In as-prepared YVO(4):Yb(3+), Er(3+)@Ag hybrids colloids, more than one order UCL enhancement than YVO(4):Yb(3+), Er(3+) was observed. Powder and the annealing samples lead the UCL enhancement effect to disappear. The main UCL enhancement mechanism of YVO(4):Yb(3+), Er(3+)@Ag hybrids colloids was attributed to prevent YVO(4):Yb(3+), Er(3+) interaction with the solution, instead of surface plasmon enhancement (SPE) effect.