Glass

=Glass=

Glasses are amorphous solids or supercooled viscous liquids. They have short range order whereby the nearest neighbor periodicity proceeds at a limited length.

Glass structure is typically modeled by tetrahedron joined by oxygen atoms at the tetrahedron verticies. Oxide glasses are typically silicates, borates, phosphates and germantes. These glasses consist of continuous random networks in which Si, B, P and Ge ions establish networks in coordination with oxygen. These are //network formers//. //Intermediate// elements can substitute the formers adjust mechanical and optical properties. Other elements, //network modifiers//, such as alkali and alkaline earth ions, modify the primary network by residing within the voids. Colorants adsorb frequencies of light lending color to the glass.


 * ~ Type ||~ Additives ||
 * Primary network || SiO2, B2O3, P2O5, GeO2 ||
 * Network Modifiers || BaO, CaO, K2O, Li2O, Na2O,MgO ||
 * Intermediates || Al2O3, PbO, TiO2, ZnO ||
 * Colorants || Cd (red), Co (blue), Cr (green), Cu (cyan), Fe (brown), Mn (magenta) ||

Dental Ceramics [\Review by Hench]

Glass-Ceramics

Glass-ceramics are a partial nucleation of ceramic phase in a glass matrix. These materials are made by a succession of heat treatments initiated by nucleation additives such as noble metals, florides and some metal oxides. The result is usually a tough, strong, pore-free glass product often used in cookware. A second variation is the use of glass particles, which self- nucleate due to surfaces morphology. However, products made from particles result in 0.5-3% porosity. The first synthetic glass-ceramic was discovered by Stanley Stookey at Corning Glass works who mistakenly overheated a piece of lithium disilicate glass. Instead of finding pool of glass in the furnace, he discovered a white product which had remarkable toughness. His discovered launched the CorningWare product and an international research field.