Control of nucleation in glass ceramics

Glass ceramics are advanced materials composed of one or more glass and crystal phases. By developing base glasses with appropriate compositions and by controlling crystal nucleation and growth in these glasses, glass ceramics with tailor–made properties can be fabricated. The key to developing this type of material is control of the nucleation processes. Both volume and surface nucleation can be exploited. Heterogeneous volume nucleation has been used to develop glass ceramics showing minimal thermal expansion and high strength. Two nucleation mechanisms can be combined and the precipitation of two crystal phases can be controlled. That the nucleation processes can be controlled by nano– and microscale immiscibility is a special feature, allowing selective nanophase formation or the development of needle–like apatite phases demonstrating a natural morphology. This represents a biomimetic process. The control of nucleation has enabled the development of biomaterials for dental applications.