Nano lamellae composed of yttrium aluminum garnet and yttrium silicate by surface crystallization of glass

Abstract

Glasses with the mol% composition 17 Y2O3, 33 Al2O3, 40 SiO2, 2 AlF3, 3 CaO, 2 CeF3, 3 B2O3 were thermally annealed at 950 and 1000 °C for different periods of time. The crystallization kinetics as well as the mechanism of surface crystallization was clarified using X-ray diffraction, optical and electron microscopy as well as fluorescence microscopy. The surface nucleation led to a coupled growth of eutectic yttrium aluminum garnet (YAG). This surface layer consists of a lamellar structure composed by YAG and yttrium silicate. The nano lamellae originated from the surface and grew in an interpenetrating cell structure with an interspace of about 50 nm. The YAG surface layer is doped with cerium as seen from the intense broadband fluorescence.