Photoluminescence of Er/Yb-doped zinc-silicate glass and glass ceramics with ZnO and Zn2SiO4 nanoparticles

Zinc-silicate glass-ceramic materials based on ZnO and Zn₂SiO₄ nanoparticles distributed in amorphous silica matrix represent one of the most perspective options to improve the photoluminescence properties of E^r3+ ions, thanks to their low phonon energy and the possibility of energy transfer between the ZnO/Zn₂SiO₄ nanoparticles and Er³⁺ ions. In this paper, we focus on the investigation of crystallization in the sodium- and potassium-zinc-silicate system and the photoluminescence properties of Er₃₊ -doped glass-ceramic materials. It was found that the presence of Na2O promotes the crystallization of Zn2SiO4 resulting in non-transparent glass-ceramic material at 750 °C, whereas the K₂O-ZnO-SiO₂ material remained transparent in the entire heat treatment range. Nevertheless, the crystallization of ZnO and Zn2SiO₄ leads to an increase of photoluminescence intensity of Er³⁺ ions by up to 300 % compared to the pre-cursor glass. The Stark-splitting of the Er³⁺ emission spectra at 1.5 μm after 978 nm excitation as well as shortening of the fluorescence lifetime suggest the incorporation of Er³⁺ ions inside the highly symmetric environment of ZnO and Zn₂SiO₄.