Crystallization Aspects of Lithium Aluminosilicate Glass Microspheres Produced in High-Temperature Plasma Flow

The influence of the spheroidization process occurring in 1.0 mol.% Nd2O3 doped Li2O-Al2O3-SiO2 (LAS) glass in a high-temperature plasma flow on the properties of glass crystallization was investigated. The resulting 32 - 64 mu m microspheres are characterized by a significantly higher glass transition temperature T-g compared to that of the original glass, which could be associated with both a change in the chemical composition on spheroidization and a fundamentally different thermal history of the microspheres and glass. In spite of the moderation of the crystallization kinetics, in microspheres as well as in the original glass, under the influence of heat treatment, a glass-ceramic structure is formed based on a-eucryptite-like solid solutions LixAlxSi1-xO2, indicating the possibility of obtaining microspheres with glass-ceramic structure as well as varying their linear thermal expansion coefficient near zero values.