Chapter 3 - Amorphous silica

Abstract

This chapter reviews amorphous silica. Amorphous silica, a noncrystalline form of SiO2, traditionally called “silica glass” or “vitreous silica,” is important in electronics and photonics because of its excellent electrical and optical properties. This chapter uses these different names interchangeably to represent all noncrystalline SiO2. The structure and basic properties of silica are also discussed. Structural study of amorphous materials is carried out by radial distribution analysis. Radial distribution analysis provides information on the short-range order of the structure. The structure obtained is consistent with the random network model. Amorphous silica consists of SiO4 tetrahedral units, with the Si-O and O-O distances. This chapter discusses the various defects in amorphous silica that influence various glass properties, especially optical and electrical properties. These defects are created either by radiation or by mechanical stresses. Real amorphous silica contains impurities such as water, chlorine, fluorine, alkali, and alumina. This chapter further discusses chemical, mechanical, optical, and electrical properties of amorphous silica.