Large-scale synthesis and luminescence of GdPO 4 hollow microspheres.

GdPO 4 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 4 hollow microspheres have a pure hexagonal phase. The SEM and TEM images confirmed that the as-obtained GdPO 4 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 4 :Yb 3+ , Ln 3+ (Ln 3+ = Tm 3+ , Er 3+ and Ho 3+ ) hollow microspheres were systematically investigated, which show blue (Tm 3+ , 1 G 4 → 3 H 6 ), green (Er 3+ , 4 S 3/2 , 2 H 11/2 → 4 I 15/2 ), and red (Ho 3+ , 5 F 5 → 5 I 8 ) 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.