Structure and Crystallization Behavior of Glasses

Almost all optical and technical glasses contain micro‐heterogeneities which can be seen using an electron microscope. These heterogeneous regions are shaped like small drops, and their size (20 to 500 Å) depends on the construction of the glass, on its temperature‐history, on the field strength of the cations, and also on the adjacent gas atmosphere. ‐ Preparation of valuable ultramicrocrystalline ceramics for industrial use from ordinary and photosensitive glasses involves controlled phase‐separation processes and subsequent crystallization.