Green (525, 550 nm, Er3+ transition (2H11/2, 4S3/2) → 4I15/2), red (660 nm, 4F9/2 → 4I15/2), blue (440 – 490 nm, 4F3/2,5/2,7/2 → 4I15/2), violet (410 nm, 2H9/2 → 4I15/2), and near ultraviolet (380 nm, 4G11/2 → 4I15/2) upconversion luminescence in langatate (La3Ga5.5Ta0.5O14) doped with erbium and ytterbium ceramic sample, synthesized by solid state reaction in air, was obtained by pumping at 973 nm. Yb3+ – Er3+ energy transfer processes accounting for population of the emitting levels are discussed. The measured lifetimes of the emitting and intermediate Er3+ levels are compared with the radiative lifetimes estimated with the Judd-Ofelt theory.
In this paper we present new results concerning the optical and morphologic properties of YVO4:Eu red nanophosphor
prepared by a precipitation method and subsequently annealed in air at various temperatures. We monitored the morphologic changes induced by the thermal treatments using the optical spectroscopy (reflectance and luminescence spectra), XRD and electron microscopy. The annealing leads to an increase of the particle size and improvement of the order of the crystalline lattice of YVO4. The annealing at 800°C produces the sample with the highest luminescence intensity.