Novel behaviour and structure of new glasses of the type Ba-Al-O and Ba-Al-Ti-O produced by aerodynamic levitation and laser heating.

Novel barium aluminate (BaAl(2)O(4)) and barium alumino-titanate (BaAl(2)TiO(6)) glasses have been produced by aerodynamic levitation and laser heating. BaAl(2)O(4) forms a clear and colourless glass under containerless and rapid quenching conditions. Under similar rapid quenching conditions BaAl(2)TiO(6) forms an opaque and black glass, while under slower and controlled quenching conditions it is possible to form a clear and colourless glass. The formation of the opaque or clear glass is reversible and purely dependent on the quench rate used. By slowing the quench rate further, it is possible to produce a milky glass suggestive of liquid-liquid phase separation in the liquid before glassification. High-energy x-ray diffraction experiments confirm the glassy state of these materials and show coordination structures and bond distances similar to their crystalline analogues.