Facile preparation and fluorescence enhancement of yolk-like Ag@Y2O3:Yb3+,Tm3+ hollow structured composite

A yolk-like Ag@Y2O3:Yb3+,Tm3+ hollow structured composite was prepared through a layer-by-layer technique by coating a carbon layer on Ag seeds and further coating a Y2O3:Yb3+, Tm3+ layer, followed by a subsequent calcination process. The phase, morphology, structure, formation process, and up-conversion properties are well characterized by various techniques. XRD results show that all diffraction peaks of the products are consistent with standard values for the pure cubic phase of Y2O3 and cubic Ag. TEM images demonstrate that the interior space of the composite can be tuned by altering the thickness of the carbon layer. Moreover, the possible evolution mechanism from Ag cores to the final yolk-like structured composite is described. By doping the Yb3+ and Tm3+ ions into the Y2O3 host matrix, these particles show blue ((1)G(4) -> H-3(6)) and near infrared (H-3(4) -> H-3(6)) emissions with different intensity depending on carbon layer thickness under 980 nm NIR laser excitation. Therefore, this material has potential for application in biomedical fields. In addition, the synthetic route may be of great value in the preparation of other hollow materials.