Rapid, morphology-controllable synthesis of GdOF:Ln3+ (Ln = Eu, Tb) crystals with multicolor-tunable luminescence properties

Abstract

In this paper, GdOF crystals with high uniformity, monodispersity and a variety of well-defined morphologies, such as spheres, nanorods, and nanorod bundles have been successfully synthesized via the urea based homogeneous precipitation method followed by a heat treatment. The influence of pH values, fluoride sources and reaction time on the sizes and morphologies was systematically investigated and discussed. The possible formation mechanism for the precursor has been presented. Under ultraviolet excitation, the GdOF:Ln³⁺ (Ln = Eu, Tb) submicron spheres show their characteristic f–f emissions and give red, and green emissions, respectively. Moreover, for Tb³⁺/Eu³⁺ co-doped GdOF phosphors, tunable emissions have been obtained and the color tones can be tuned from green, through yellow, and then to red by simply adjusting the doping Eu³⁺ concentrations. This merit of multicolor emissions in the visible region makes these materials hold great promise for applications in field-emission displays.