Multicolor tunable luminescence and energy transfer of core–shell structured SiO2@Gd2O3 microspheres co-activated with Dy3+/Eu3+ under single UV excitation
Optimizing structure and varying doped ions are two main strategies to obtain excellent luminescence performance. Spherical morphology is considered to be the most ideal phosphor structure due to the least surface defects. Herein, a series of spherical and monodispersed Dy3+/Eu3+ co-activated SiO2@Gd2O3 core–shell phosphors with multicolor tunable luminescence were successfully prepared via a facile urea assisted precipitation method. Related chemical reactions and the possible growth mechanism of Gd2O3:Ln3+ directional deposition on the surface of SiO2 microspheres were put forward. Upon 273 nm UV radiation excitation, SiO2@Gd2O3:Dy3+ and SiO2@Gd2O3:Eu3+ samples exhibited characteristic yellow (4F9/2–6H13/2) and blue (4F9/2–6H15/2) emissions of Dy3+ and red (5D0–7F2) emission of Eu3+, respectively. Meanwhile, multicolor emissions (warm white, yellow and orange) could be easily obtained by modulating the relative content of Dy3+ and Eu3+ in SiO2@Gd2O3:Ln3+ samples under a single excitation wavelength. Moreover, it was confirmed that Dy3+ could transfer energy to Eu3+ in the form of quadrupole–quadrupole interaction and further improved the luminescence intensity of Eu3+ by comparing experimental data with theoretical calculations. These results imply that tunable luminescence Dy3+,Eu3+ co-doped SiO2@Gd2O3 microspheres have great potential applications in multicolor displays and biolabeling fields.