Controlled phase separation by an electric field in glasses

Externally applied electric field has a significant effect on phase separat ion of glasses. At low BaO contents, spherical barium-rich phase separation is promoted due to the greater (epsilon(2)/epsilon(1) > 1) ratio of the di electric constants of the new phases than the old. Increasing BaO contents to 0.1 mol%, owing to the interconnected phase separation produced, the ele ctric field has no effect on the phase separation. At higher BaO contents, spherical silica-rich phase separation is retarded. This means that the ele ctric field can either stimulate or inhibit the phase separation process. F urthermore, we may control phase separation of glasses. These results sugge st a new method for the preparation of nanocrystalline glass ceramics. (C) 1999 Elsevier Science S.A. All rights reserved.