Improvement of blue, white and NIR emissions in YPO4:Dy3+ nanoparticles on co-doping of Li+ ions.

As-prepared samples of YPO(4):2Dy nanoparticles prepared by polyol route show strong blue luminescence because of strong host contribution, whereas 500 and 900 °C annealed samples show cold and warm white luminescence, respectively because of different energy transfer rates from host to Dy(3+). Li(+) co-doping improves luminescence intensity as well as crystallinity significantly. Interestingly, Li(+) ions occupy interstitial sites of lattice. These materials will be potential candidates for white light emitting diodes and near-infrared emitting phosphors.