Study of thermal behaviour of yttrium-aluminate glasses by DSC and high temperature XRD analysis

Yttrium-aluminate glasses with high alumina content are potential candidates for various applications ranging from transparent ballistic protections, through infrared transparent windows, to hosts for rare earth elements in materials used for solid state lasers. These glasses are interesting because of their optical and mechanical properties and high chemical and thermal stability. Preparation of bulk Al2O3-Y2O3 glasses is very time and energy consuming and prepared materials are very expensive. Different ways of mentioned bulk glasses preparation were reported, however the combination of flame synthesis and subsequent HP sintering of glass microspheres published by Rosenflanz seems to be very promising from technological and economic point of view. In this work the glass microspheres with different alumina content were prepared by flame synthesis. The morphology of prepared particles was studied by optical microscopy and SEM, XRD, DSC and high temperature XRD analysis were performed in order to determine of optimal conditions for hot-press sintering of glass microbeads

Preliminary study of thermal properties of Al₂O₃-Yb₂O₃ glass microspheres

Binary ytterbium-aluminate glass microspheres with eutectic (79.4 mol. % Al2O3, 20.6 mol. % Yb2O3) composition were prepared by flame synthesis in methan-oxygen flame. The starting powder was prepared by sol-gel method in order to obtain homogenous glass particles with a narrow interval of particle size distribution. Prepared microspheres were studied by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and differential thermal analysis (DTA). According to the XRD, small portion of YbAG, α-Al2O3 and non-identified phase were present in glass microspheres after flame synthesis. From DTA records, temperatures of onset of crystallization (Tc) and temperature of maxima of the exothermic crystallization peak (Tx) were determined. High temperature X-ray diffraction analysis (HT-XRD) in temperature range 750-1200 °C with 2h and 4h isothermal holding time at temperatures 933 and 1044 °C was performed for preliminary study of thermal behaviour of prepared system