Glasses: Structure

Abstract

This chapter discusses about glasses that are characterized by an absence of atomic periodicity and it is this inherent disorder that complicates structural studies and interpretations. The structure of glasses can best be understood on an atomic scale and the structure for a specific glass will depend on how it was produced. The basis for the structural studies of amorphous materials is the radial distribution function. As glasses are characterized by the short-range ordering of atoms and an absence of long-range order, structural models have been derived mainly from the liquid and crystalline states. The two most prevalent models are the microcrystalline and the random network. The structure of vitreous silica was studied by X-ray diffraction using improved experimental and analytical techniques. The structure of vitreous germania has been studied by neutron and X-ray diffraction. X-ray diffraction and nuclear magnetic resonance studies have defined the basic building blocks of vitreous boron oxide as triangles. Glasses made from ionic salts such as beryllium fluoride and zinc chloride have tetrahedra as the units of composition, which generate a random network believed to be similar to vitreous silica.