Core-shell-core heterostructural engineering of Y_2O_3:Eu~(3+)/MCM-41/YVO_4:Eu~(3+) for enhanced red emission and tunable, broadened-band response to excitation

摘要

For the first time, a hierarchical phosphor Y_2O_3:Eu~(3+)/MCM-41/YVO_4:Eu~(3+), with a core-shell-core heterostructure, is presented in this study. Synergistically bridging the phosphors Y_2O_3:Eu~(3+) (as an inner core) and YVO_4:Eu~(3+) (as an outer core) by amorphous SiO_2, i.e., MCM-41 (with ordered mesoporous channels) leads to the generation of the core-shell-core heterostructure with enhanced red emission and tunable, broadened-band response to excitation. The novel structure of the core-shell-core hierarchical material is clarified through various characterization methods including X-ray diffraction analysis, transmission electron microscopy, selected-area electron diffraction and N_2 adsorption-desorption measurements. Significantly, through temperature-dependent fluorescence investigation, it is found that our core-shell phosphor (Y_2O_3:Eu~(3+)/MCM-41) exhibits impressive fluorescence stability against temperature variation (27-227 °C) due to the protective effect resulting from MCM-41. By contrast, lowered stability can be noted for the core-shell-core phosphor (Y_2O_3:Eu~(3+)/MCM-41/YVO_4:Eu~(3+)), especially when the temperature is higher than 100 °C, owing to the outer core (YVO_4:Eu~(3+) nanoparticles) that is directly exposed to heat. Such a kind of luminescent materials holds substantial promise for labeling the organisms that are vulnerable to short-wavelength UV light irradiation. Additionally, potential intelligent systems can be expected to be designed on the basis of the fluorescence mutation as triggered by the temperature of 100 °C.