Introduction to Glass and Glass-Ceramic Background

Glass is a product of inorganic fusion obtained by cooling down molten inorganic materials to a rigid condition. Glass ceramics are known, which include an amorphous phase and one or more crystalline phases. Nowadays, glass ceramics are used in different fields such as communications technology and electrical devices. Sintering is known as a shaping process for materials, such as glass and glass ceramics, with extremely high melting points. For instance, in the fabrication of semiconductors, impurities are usually introduced into the host lattice to modify their electrical and optical properties. Doping processes are mainly important for the creation of electronic junctions in silicon and for manufacturing of semiconductor devices. At present, phosphate glasses are commonly utilized for bulk laser applications. However, they are not very suitable for integrated optics purposes, because of their poor chemical stability and low transition temperatures. Conversely, silicate glasses have much better chemical stability, which is important for ion exchange techniques to fabricate optical wave guides. Among oxide glasses, phosphate and silicate glasses are the two most important materials, and they have been used extensively for lasers and fiber. Compared with silicate glasses, phosphate glasses are more limited in their use because they are hydroscopic in nature and have a lower glass transition temperature.