Dual-mode upconversion and downshifting white-light emitting Ln3+:Gd2W2O9 materials

Abstract

Microsized Gd₂W₂O₉ materials, doped with different Ln³⁺ ions, showing either downshifting (Dy³⁺) or upconversion (Tm³⁺, Er³⁺, Yb³⁺, Ho³⁺) white-light emission, have been synthesized employing a microwave-assisted co-precipitation method. Two different approaches to achieve dual-mode white-light emission were explored in this work. The first one implies mixing two samples: the downshifting Dy³⁺:Gd₂W₂O₉ material and the upconversion Tm³⁺,Er³⁺,Yb³⁺,Ho³⁺:Gd₂W₂O₉ compound; the other consists of preparing a material which is co-doped with all five Ln³⁺:Dy³⁺,Tm³⁺,Er³⁺,Yb³⁺, and Ho³⁺. For each material, the corresponding luminescence spectra were investigated in detail and the CIE coordinates were calculated.