Activation of Tm3+ single-photon NIR-to-NIR upconversion luminescence through Yb3+ doping in Tm2WO6 phosphor

Ceramic phosphors Tm 2-x WO 6 :xYb 3+ synthesized by solid-state reaction method. The up-conversion (UC) dynamics in the Yb 3+ -doped Tm 2 WO 6 phosphor were investigated, which demonstrated a single-photon UC process from a near-infrared (NIR) excitation at 980 nm to an NIR emission corresponding to the 3 H 4 → 3 H 6 transition of Tm 3+ . X-ray photoelectron spectra confirmed the chemical states of the constituent elements. The diffuse reflectance spectra confirmed that Tm 2 WO 6 requires doping with Yb 3+ ions in order to be able to absorb the energy at 980 nm. UC emission properties of the phosphors depend on the Yb 3+ ion concentration. NIR emission of Tm 3+ is much stronger than visible emissions when Yb 3+ doping. The NIR and red emissions were caused by a single-photon UC process, whereas the blue emission was caused by a two-photon process. The temperature-dependent UCL showed an initial rise in the UC intensity and then a consistent decrease with the variation in temperature. • Ceramic phosphors Tm 2-x WO 6 :xYb 3+ synthesized by solid-state reaction method. • XPS analysis was performed to identify the chemical states of the ceramic phosphor. • UC emission properties of the phosphors depend on the Yb 3+ ion concentration. • NIR emission of Tm 3+ is much stronger than visible emissions when Yb 3+ doping.