Tunable photoluminescence induced by thermal reduction in rare earth doped glasses

Abstract

In this paper, we show that the photoluminescence of Eu and Eu–Yb doped silicate glasses can be tuned by heat-treating the glasses in reducing atmosphere and by adjusting their host compositions. The control over the rare earth redox state in glasses is crucial for their potential applications as phosphor materials. By subjecting the glasses to a H₂-bearing atmosphere around the glass transition temperature, Eu³⁺ ions are reduced to Eu²⁺, and this leads to modification of the glass surface chemistry and structure. Both the underlying reduction mechanisms and the composition dependence of luminescence are clarified based on static and dynamic emission spectroscopy, surface analysis, and structural considerations. The tunability of the energy transfer (i.e., quantum cutting) from Eu²⁺ to Yb³⁺ in the co-doped Eu–Yb glasses is also explored.