Morphology control and multicolor-tunable luminescence of YOF:Ln3+ (Ln = Eu, Tb, Dy, Tm) nano-/microcrystals

Abstract

YOF:Ln³⁺ (Ln = Eu, Tb, Dy, Tm) nano-/microcrystals with high uniformity, monodispersity and a variety of well-defined morphologies, such as submicro spheres, ellipsoids, nanorods, microspindles and spindle nanorod bundles, have been successfully synthesized via a urea based homogeneous precipitation method followed by a heat-treatment process. The influence of pH values, fluoride sources and reaction time on the sizes and morphologies of the as-prepared precursor was systematically investigated and discussed. The possible formation mechanism for the precursor has been presented. Upon ultraviolet excitation, the YOF:Ln³⁺ (Ln = Eu, Tb, Dy, Tm) submicro spheres show their characteristic f–f emissions and give red, green, yellow, and blue emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor YOF:Tm³⁺,Dy³⁺ was also successfully fabricated by singly varying the doping content of Dy³⁺ with a fixed Tm³⁺ content through the principle of energy transfer. This merit of multicolor emissions in the visible region endows materials of this kind with potential application in field-emission display devices and white light-emitting diodes.