Ag-Y2O3:Eu3+ composite nanotubes: synthesis, tunable photoluminescence and surface-enhanced Raman scattering

Ag-Y2O3:Eu3+ composite nanotubes were synthesized by growing Ag nanoparticles on the surface of Y2O3:Eu3+ nanotubes. The effects of the Ag content on the photoluminescence properties of the Ag-Y2O3: Eu3+ composite nanotubes were investigated in detail. In addition to the charge transfer from the 2p orbital of O-2 to the 4f orbital of Eu3+, several sharp lines corresponding to the f-f transitions of Eu3+ were also observed in the excitation spectra of the Y2O3:Eu3+ nanotubes monitored at different emission wavelengths. However, only one excitation band centered at 535 nm was observed in the excitation spectrum of Ag-Y2O3:Eu3+ monitored at 590 nm, which is different from that monitored at 614 nm. We suggest that the change in the excitation spectra between Y2O3:Eu3+ and Ag-Y2O3:Eu3+ is attributed to the interaction between Ag and Ag-Y2O3:Eu3+. In particular, the inhomogeneous linewidth of the D-5(0) -> F-7(1) transition from Ag-Y2O3:Eu3+ was observed to broaden when the excitation wavelength was set at 535 nm. Decay dynamics were performed to study the photoluminescence of the Ag-Y2O3:Eu3+ composite nanotubes, and the decay curve can be well fitted with a second order exponential decay function. Moreover, the surface-enhanced Raman scattering effect of the Ag aggregates was evaluated by using 4-aminothiophenol as a Raman probe molecule. It was demonstrated that a high SERS signal can be observed by increasing the Ag : Ln(3+) ratios in the Ag-Y2O3:Eu3+ composite nanotubes.