A homogeneous solution of Y3+, Bi3+, and Eu3+ in methanol was used for low-temperature (70°C) synthesis of YVO4:Bi3+, Eu3+ nanoparticles. X-ray diffraction and fluorescence analyses revealed phase-pure tetragonal YVO4:Bi3+, Eu3+. Transparent colloidal solutions were prepared having well-dispersed ∼8-nm YVO4:Bi3+, Eu3+ nanoparticles. Increases in elemental Bi content at the constant Eu content increased the lattice spacing linearly. This reveals that Bi3+, which is larger than Y3+ and Eu3+, substitutionally incorporated in YVO4:Eu3+. The absorption edges and photoluminescence excitation edges were red-shifted by doping Bi3+ in YVO4:Eu3+, and red emission from Eu3+ was observed under near-ultraviolet excitation. These results indicate that Bi3+ and Eu3+ were successfully co-doped into the YVO4 host crystal. Concentration quenching was not observed with increasing Bi-doping even until 6.5 at%, although the quenching of bulk YVO4:Bi3+, Eu3+ prepared by solid-state reaction was observed with >3 at% in a previous report. This implies a better chemical homogeneity of Bi in the host crystal or a structural disorder which prevents the energy migration between Bi3+.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials