On the glass transition temperature in covalent glasses

We give a simple demonstration of the formula relating the glass transition temperature, T-g, to the molar concentration x of a modified in two types of glasses: binary glasses, whose composition can he denoted by X(n)Y(m) + xM(p)Y(q), with X an element of 3rd or 4th group (e.g., B or Si, Ge), while M(p)Y(q) is an alkali oxide or chalcogenide; next, the network glasses of the type A(x)B(1-x), e.g., GexSe1-x, SixTe1-x, etc. After comparison, this formula fives an exact expression of the parameter beta of the modified Gibbs-Di Marzio equation.