Enhancement of upconversion emission and temperature sensing of paramagnetic Gd2Mo3O9: Er3+/Yb3+ phosphor via Li+/Mg2+ co-doping

Herein, enhancement of upconversion emission and temperature sensing in Li+/Mg2+ co-doped Gd2Mo3O9:Er3+/Yb3+ is reported. The upconversion emission enhancement of 53 and 21 times is observed in green (524 nm) and red (660 nm) emission bands via simultaneous co-doping of Li+/Mg2+ ions and is explained in terms of radiative and non-radiative transition rates. High thermal sensitivity of the material is realized upon Li+/Mg2+ co-doping by measuring the fluorescence intensity ratio of two thermally coupled energy levels (H-2(11/2) & S-4(3/2)) of Er3+ ion. The maximum absolute sensitivity of 0.0230 K-1 at 513 K is found for present material and is among the highest measured sensitivities for luminescence based thermometers. Additionally, improved magnetization and magnetic mass susceptibility is also observed on co-doping of Li+/Mg2+ in the material. The result suggests that simultaneous incorporation of Li+/Mg2+ is an effective approach for enhancing multifunctionality of Gd2Mo3O9:Er3+/Yb3+ phosphor and this material has potential applications in colour displays, high temperature sensing and magnetic resonance imaging. (C) 2018 Published by Elsevier B.V.