Silver doped glasses from the system BaO/SrO/ZnO/SiO2 – The influence of Sb, Sn, and Ta on the formation of core-shell structures. Issue 1 (1st January 2021) - Thieme, Christian
Abstract: Three glasses from the base system BaO/SrO/ZnO/SiO2 have been synthesized using conventional melt quenching technique and different concentrations of Ag, Sn, Sb, and Ta. After two-step heat treatments, two glasses showed volume crystallization, while the third glass crystallized solely from the surface. The different crystallization mechanisms were studied by differential scanning calorimetry and both scanning and transmission electron microscopy. It was found that the formation of LEAZit (Low Expansion Alkaline Earth Zinc Silicates) volume crystals runs parallel to the formation of core-shell structures inside the glassy matrix. Such a core-shell structure consists of a metallic Ag core, which is surrounded by a shell composed of Zn2 SiO4 . Into this crystalline phase, Sb, Sn, as well as Ta can be incorporated. Glasses without Sb show the formation of metallic and spherically shaped Ag particles without any shell, being unsuitable to trigger volume crystallization in the studied glasses. Hence, the presence of Ag, Sn, Sb, or Ta in a suitable ratio is decisive for the nucleation and crystallization mechanism of the studied glasses.