Effects of citrate additive on transparency and photostability properties of YVO₄: Bi³⁺, Eu³⁺ nanophosphor

YV O₄: Bi³⁺, Eu³⁺ nanoparticles were prepared by the wet chemical synthesis in various concentrations of sodium citrate, 15≤ x_cit ≤90, where x_cit is the nominal molar percentage of citrate relative to the sum of metallic ions, Y ³⁺, Bi³⁺, and Eu³⁺. Mean primary nanoparticle diameter and mean hydrodynamic size in the aqueous colloidal solution have minimum values, 21 and 36 nm, respectively, for the sample prepared at x _cit =50. The transparency of the aqueous colloidal solution in the visible region increases with decreasing the mean hydrodynamic size, and the sample prepared at x_cit =50 shows the highest transparency. YV O ₄: Bi³⁺, Eu³⁺ nanoparticles show the characteristic photobleaching behavior and the photoreduction of V⁵⁺ to V⁴⁺ under the irradiation of near-UV light, where the fraction of photobleach becomes larger at large x_cit. These results suggest that the citrate ion works not only as an effective dispersion agent, but also as a reducing agent against V⁵⁺ of YV O₄: Bi³⁺, Eu³⁺.