Synthesis and luminescence properties of colloidal YVO4 : Eu phosphors

Concentrated colloidal solutions of well-dispersed YVO4:Eu nanoparticles ar e synthesized by precipitation reactions at room temperature and stabilized by sodium hexametaphosphate. X-ray diffraction and electron microscopy cha racterizations show that the crystalline nanoparticles exhibit an ellipsoid al form with two characteristic dimensions of around 15 and 30 nm. In compa rison with the bulk, a lower luminescence efficiency as well as a higher co ncentration quenching are observed. These deviations are explained as the v ariations of some characteristics of the colloidal samples, such as the cry stallinity and the surface chemistry. When these parameters are optimized, the quantum yield of the luminescence reaches 38% for the nanoparticles con taining a europium concentration of 15%.