Up-conversion white emission and other luminescence properties of a YAG:YbO·TmO·HoO@SiO glass-nanocomposite.

We report on a glass-nanocomposite material consisting of yttrium aluminum garnet (YAlO, YAG) nanocrystals co-doped with Yb, Tm and Ho ions as well as entrapped into a SiO xerogel. This 94YAG·5YbO·0.8TmO·0.2HoO@SiO (abbr. YAG:YbTmHo@SiO) 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 = 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 SiO matrix and for some transitions of the Tm and Ho dopants present in the YAG:YbTmHo@SiO 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.