Thermal and optical properties of glass and crystalline phases formed in the binary R2O3-Al2O3 (R = La-Lu and Y) system

Rare-earth aluminate (RAlO3, R = La–Lu and Y) glass and crystalline phases were prepared by containerless levitation in an aerodynamic levitation furnace. In the RAlO3 system, La, Nd and Sm aluminum perovskites solidified as glass and Eu–Lu and Y aluminum perovskites solidified as crystalline phases. The glass forming region decreased with decreasing ionic radius of the rare-earth element. Scanning electron microscopy images and x-ray diffraction results revealed the formation of a single RAlO3 phase from the undercooled melt. The glass transition temperature, Tg, and density increased and the molar volume decreased with decreasing rare-earth element ionic radius. The refractive index at 589 nm exceeds 1.85 in each composition and a transparency of approximately 72% was achieved for the LaAlO3 glass.