A MODEL OF GLASS-TRANSITION IN BINARY AND TERNARY GLASSES

We propose a simple model of glass formation for various types of cova lent and network glasses: binary covalent glasses, with the compositio n denoted by XnYm + xM(p)Y(q), with X an element of III-rd or IV-th gr oup (e.g. B, Al, or Si, Ge), while MpYq is an alkali oxide or chalcoge nide; next, the covalent network formers of the type A(x)B(1-x) e.g. G exSe1-x, SixTe1-x, etc. Finally, certain ternary glasses, with two dif ferent modifiers present, are also discussed. A simple formula relatin g the glass transition temperature T-g to the modifier consentration i s derived. We give examples which show a good agreement of our formula with the experimental data. (C) 1997 Elsevier Science B.V.