Oriented fluororichterite/diopsid glass-ceramics prepared by electrochemically induced nucleation

Glasses in the system Na2O–MgO–CaO–SiO2–F− were crystallized using electrochemically induced nucleation. For that purpose, a platinum crucible containing the melt was used as anode while a platinum wire inserted into the melt acted as cathode. A dc-potential of 1 V supplied between the electrodes led to a current flow of 10 mA. This resulted in nucleation at the cathode and subsequently to radial growth of fluororichterite and diopsid crystals. Both crystalline phases were oriented with their crystallographic c-axis radially, i.e., perpendicular to the electrode surface. The structures formed are described and the mechanism leading to nucleation and subsequent crystal growth is discussed.