Hydrothermal synthesis and luminescent properties of YVO4:Ln(3+) (Ln = Eu, Dy, and Sm) microspheres.

Rare-earth ions (Eu(3+), Dy(3+), Sm(3+)) doped YVO(4) microspheres with uniform morphologies were successfully prepared via a simple hydrothermal route using N,N-dimethylformamide (DMF) as the solvent and polyvinylpyrrolidone (PVP) as protective agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and the kinetic decays were employed to examine the resulting phase formation, particle morphology and luminescent properties. The XRD results reveal that all the doped samples are of high crystallization which are assigned to the pure tetragonal phase of YVO(4). Additionally, the DMF/H(2)O volume ratio and the concentration of PVP both have obvious effects on the morphologies and sizes of the as-synthesized products. The sample prepared at 180 degrees C for 24 h with the DMF/H(2)O volume ratio of 3/1 and 0.4 g/L PVP concentration exhibits uniformly spherical shape with the diameter of 1-2 microm. Upon excitation by ultraviolet radiation or low-voltage electron beams excitation, the YVO(4):Ln(3+) (Ln=Eu, Dy, and Sm) samples show strong light emissions with different colors from the doped Ln(3+) ions. These phosphors exhibit potential applications in the fields of fluorescent lamps and light emitting diodes (LEDs). 2009 Elsevier Inc. All rights reserved.