Glass-ceramics, also known as microcrystalline glass or microcrystalline ceramics, were invented in the mid-1950s by the renowned glass chemist and inventor S. D. Stookey. They are polycrystalline solid-phase materials containing a glassy matrix, produced by controlled nucleation and crystallization of base glasses with specific compositions at controlled temperatures. The properties of glass-ceramics are primarily determined by the main crystalline phase, which can be controlled through nucleation, crystallization, and the selection of different parent glass components. Glass-ceramics combine the characteristics of both glass and ceramics, exhibiting superior thermal, chemical, biological, optical, and electrical properties compared to metals and polymers.
Composition and microstructure are the two main influencing factors in the design of glass-ceramic compositions. The main component is the decisive factor in nucleation. For glass-ceramics with mechanical and optical properties, microstructure is an even more critical factor, related to the main component and the aggregation of the microcrystalline phase. Different heat treatment regimes also significantly affect the microstructure. Controlling the crystallization of the glass is a prerequisite for the formation of glass-ceramics. Nucleation is the decisive factor in controlling crystallization. The formation of crystals in the mother glass typically involves two stages: ① submicroscopic nucleus formation stage; ② submicroscopic nucleus growth stage. These two stages are referred to as nucleation and crystal growth, respectively. Nucleation is influenced by two factors: ① selecting a mother glass with a suitable chemical composition, usually by adding a certain nucleating agent; ② controlling the heat treatment regime, i.e., the heating temperature and holding time.
