Crystallization of Y2O3-Al2O3 Rich Glasses: Synthesis of YAG Glass-Ceramics

An yttria-alumina glass incorporating 4 wt % of SiO2 was prepared by the use of an aerodynamic levitator equipped with a laser heating device. Upon post synthesis annealing, the glass is observed to exhibit crystallization below the glass transition temperature. In the current study, this unusual behavior is examined using powder X-ray diffraction and infrared spectroscopy to follow crystallinity and optical absorbance as a function of annealing treatment. Double-resonance Al-27/Si-29 NMR spectroscopy and synchrotron diffraction experiments demonstrate that Si cations are incorporated in the formed Y3Al5O12 (YAG) crystals on the 4-fold coordination Al site during crystallization. This has important consequences on the resulting microstructure of the YAG glass-ceramics.