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