Synthesis and photoluminescence of (Y0.9−xLax)Eu0.1VO4 nano-crystal phosphors using a sol–gel method

The (La, Eu) co-doped YVO4 with nano-crystal phosphors were prepared using a sol–gel method. The X-ray diffraction profiles show that all of the peaks are attributed to the YVO4 phase when co-doped with the (La3+, Eu3+) ions. The intensities of the diffraction peaks decreases when the La3+ ion concentrations increase. In addition, under an excitation of 318 nm, the 5D0 → 7F2 transition intensity increased with increasing the La3+ ion concentration, and increased about five with the 15 mol% of La3+ ion doping. This is caused by the large difference in ion radius between the La3+ and Y3+ ions, which leads to a distorted lattice and a local nonuniform strain in the vicinity of the Eu3+ ions when La3+ ions substitute Y3+ ions in the (Y0.9−xLax)Eu0.1VO4 system. The bright red emission of the (Y0.9Eu0.1)VO4 phosphor has the CIE chromaticity coordinates of (0.66, 0.34) with 15 mol% La3+ ion doping, which is very close to the NTSC system standard red chromaticity coordinates of (0.67, 0.33).