Probing Dy3+ ions on the surface of nanocrystalline YVO4: Luminescence study

YVO4 nanoparticles doped with 4 at.% Dy3+ have been prepared at low temperature by urea hydrolysis. As-prepared samples show poor luminescence and thus the as-prepared nanopartricles were heated at 500 and 900 °C in order to increase crystallinity and observe the particle size effect on the luminescence study. Luminescence intensity of Dy3+ increases with heating from 500 to 900 °C. This is attributed to the extent of reduction of non-radiative transition probability which arise from the surface of particles. The charge transfer processes such as V–O and Dy–O are observed. The luminescence intensity of Dy3+ becomes highest on excitation at 315 nm (i.e. V–O charge transfer absorption peak). Luminescence intensity of Dy3+ is further improved by the core–shell formation due to the removal of the Dy3+ ions available on the surface of core particles. This has been supported by lifetime decay study of 4F9/2 level of Dy3+ and life time is longer for core–shell particles as compared to that for core particles.