STRUCTURE, GLASS-FORMATION AND PROPERTIES

Recent experimental results, chiefly from neutron scattering with isot opic substitution have shown that several silicate and phosphate glass es, containing cations of Groups I, II or transition metals, have a de gree of local and medium-range ordering that is strongly reminiscent o f compositionally-equivalent crystalline phases. The consequences of t hese results are considered and it is shown that models based on the s tructure of the corresponding crystal allow a reasonable rationalisati on of the structure of the glass, providing constraints associated wit h the liquid state are included. Borrowing structural principles assoc iated with the crystalline and liquid phases places amorphous material s where they belong: centrally in the spectrum of liquids, glasses and crystals.