Uniform and well-dispersed SiO2:x%Tb3+@Lu2O3:y%Eu3+ core–shell spherical phosphors
were synthesized via a solvothermal
method followed by a subsequent calcination process. The structure,
phase composition, and morphology of the samples were studied by X-ray
diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform
infrared spectroscopy (FT-IR), field emission scanning electron microscopy
(SEM), and transmission electron microscopy (TEM). The results showed
that the Lu2O3:Eu3+ layer was evenly
coated on the surface of SiO2:Tb3+ spheres and
the shell thickness was about 45–65 nm. The PL spectra and
fluorescence lifetimes of the samples were further studied. It was
proved that the multicolor luminescence of the samples could be realized
by changing the doping concentration ratio of Eu3+ or by
changing the excitation wavelengths. Compared with SiO2@Lu2O3:3%Tb3+,6%Eu3+,
SiO2:3%Tb3+@Lu2O3:6%Eu3+ showed stronger luminescence intensity, longer fluorescence
lifetime, and higher energy transfer efficiency, which was attributed
to the effective interfacial energy transfer, and the interfacial
energy transfer mechanism from Tb3+ to Eu3+ was
a dipole–dipole interaction mechanism. The XPS results indicated
that the sample contained a high content of Si–O–Lu
bonds, which proved that there was a strong interaction between the
SiO2 core and the Lu2O3 shell, making
the interfacial energy transfer possible. These results provided a
new idea for luminescence enhancement and multicolor luminescence.
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