Fluorescent-magnetic nanocrystals: synthesis and property of YP(x)V(1-x)O4:Eu@GdPO4 core/shell structure.

A fluorescent-magnetic YP(x)V(1-x)O(4):Eu@GdPO(4) core/shell nanostructure was prepared by a two-step method. The YP(x)V(1-x)O(4):Eu core was synthesized using a hydrothermal method, and it exhibits strong photoluminescence with the effective doping of phosphorus (P) and europium (Eu) into a YVO(4) matrix. The hydrothermal process provides a hydrophilic and fresh surface for coating GdPO(4) shell. As YP(x)V(1-x)O(4):Eu and GdPO(4) have the similar unit cell parameters, YP(x)V(1-x)O(4):Eu nanoparticles (NPs) were favorably coated by an epitaxial growth of GdPO(4) shell in aqueous phase. The core/shell nanostructure was identified by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The GdPO(4) shell not only possesses the paramagnetic character, but also enhances the photoluminescence efficiency by blocking the non-radiative de-excitation from the VO(4)(3-) groups to the surface quenching sites. These optical and magnetic properties promise outstanding fluorescent-magnetic bifunctional nanomaterials.