Up-conversion white emission and other luminescence properties of a YAG:Yb2O3·Tm2O3·Ho2O3@SiO2 glass-nanocomposite

Abstract

We report on a glass-nanocomposite material consisting of yttrium aluminum garnet (Y₃Al₅O₁₂, YAG) nanocrystals co-doped with Yb³⁺, Tm³⁺ and Ho³⁺ ions as well as entrapped into a SiO₂ xerogel. This 94YAG·5Yb₂O₃·0.8Tm₂O₃·0.2Ho₂O₃@SiO₂ (abbr. YAG:YbTmHo@SiO₂) nanocomposite material has been prepared by sol–gel procedure. Its structure and morphology has been characterized by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques as well as energy dispersive X-ray (EDX), X-ray photoelectron (XPS) and luminescence spectroscopies. The luminescent glass-nanocomposite exhibited an up-conversion effect under λ_exc = 980 nm and emission when excited under 355 nm in steady-state conditions. Then time-resolved luminescence emission was observed, when the sample was excited at 290 and 355 nm by a pulse laser. Average decay times for the SiO₂ matrix and for some transitions of the Tm³⁺ and Ho³⁺ dopants present in the YAG:YbTmHo@SiO₂ material have been evaluated. The luminescent nanocomposite when excited under 290 or 355 nm wavelengths in both conditions emits blue light. However, the nanocomposite is promising as a single-source white-light phosphor owing to its up-conversion luminescence under 980 nm excitation. Such optical features make the studied material an alternative phosphor.