Figure 4

(a–c) The UCL spectra of Er2O3 NPs, Ag-SiO2-Er2O3 composites and the UCL spectra of bulk Er2O3 under as a function of 980 nm excitation power density, respectively, (d) the UCL EF as a function of excitation power density.
(a–c) The UCL spectra of Er2O3 NPs, Ag-SiO2-Er2O3 composites and the UCL spectra of bulk Er2O3 under as a function of 980 nm excitation power density, respectively, (d) the UCL EF as a function of excitation power density.