Large-scale synthesis and luminescence of GdPO hollow microspheres.

GdPO hollow microspheres were synthesized by using a novel multi-step transformation synthetic route for the first time with polystyrene (PS) spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process, and a calcination process. The XRD results indicated that the GdPO hollow microspheres have a pure hexagonal phase. The SEM and TEM images confirmed that the as-obtained GdPO hollow spheres have a uniform morphology with an average diameter of 2.7 μm and shell thickness of about 150 nm. The up-conversion luminescence properties as well as the emission mechanisms of the GdPO:Yb, Ln (Ln = Tm, Er and Ho) hollow microspheres were systematically investigated, which show blue (Tm, G → H), green (Er, S, H → I), and red (Ho, F → I) luminescence under 980 nm NIR excitation, providing potential applications in bioanalysis, optoelectronic and nanoscale devices, future color displays and light-emitting devices, and so on.