Preparation and luminescence properties of lutetium oxide hollow spheres by a template-directed route

Graphical abstract: Display Omitted Highlights: → Uniform Lu2O3 hollow spheres have been obtained by a template-directed method. → The colloidal carbon spheres were used as template. → The main synthesis process was carried out in aqueous condition. → The Lu2O3:Ln3+ hollow spheres show intense down- and upconversion luminescence. → The hollow spheres may find potential applications in biological fields. - Abstract: Well-dispersed lutetium oxide (Lu2O3) hollow spheres have been obtained by a template-directed method with carbon spheres as template followed by a heat treatment. The main synthesis process was carried out in aqueous condition without any organic solvents, surfactant, or etching agents. SEM and TEM images reveal that the Lu2O3 hollow spheres inherit the spherical shape and good dispersion of carbon spheres, and the shells of the hollow spheres are composed of a large amount of uniform nanoparticles. The lanthanide activator ions doped Lu2O3 hollow spheres show intense down- and upconversion luminescence with different colors under ultraviolet or 980 nm light excitation, which may find potential applications in the fields of drug delivery or biological labeling. Furthermore, the luminescent mechanisms of the luminescent hollow spheres were investigated.