Concentrated colloidal solutions of well-dispersed YVO 4 :Eu nanoparticles are synthesized by precipitation reactions at room temperature and stabilized by sodium hexametaphosphate. X-ray diffraction and electron microscopy characterizations show that the crystalline nanoparticles exhibit an ellipsoidal form with two characteristic dimensions of around 15 and 30 nm. In comparison with the bulk, a lower luminescence efficiency as well as a higher concentration quenching are observed. These deviations are explained as the variations of some characteristics of the colloidal samples, such as the crystallinity and the surface chemistry. When these parameters are optimized, the quantum yield of the luminescence reaches 38% for the nanoparticles containing a europium concentration of 15%.
Solid state phosphors in the form of nanosized particles attract a lot of attention. This interest is of both fundamental and practical character. Ultrafine and homogeneous fluorescence particles can be used as biological labels and in the various lightning or display equipment.