On the glass transition temperature in covalent glasses

TL;DR

This paper demonstrates a simple formula linking the glass transition temperature to the composition in covalent glasses, providing an exact expression for a key parameter in the modified Gibbs-Di Marzio equation.

Contribution

It introduces a straightforward derivation of the relation between T_g and molar concentration in covalent glasses, clarifying the parameter β in the Gibbs-Di Marzio model.

Findings

Derived an exact formula for T_g as a function of composition.

Connected the formula to the parameter β in the Gibbs-Di Marzio equation.

Validated the formula for binary and network glasses.

Abstract

We give a simple demonstration of the formula relating the glass transition temperature, $T_g$, to the molar concentration $x$ of a modifier in two types of glasses: binary glasses, whose composition can be denoted by $X_nY_m+xM_pY_q$, with ^$X$ an element of III-rd or IV-th group (e.g. B, or Si, Ge), while $M_pY_q$ is an alkali oxide or chalcogenide; next, the network glasses of the type $A_xB_{1-x}$, e.g. $Ge_xSe_{1-x}$, $Si_xTe_{1-x}$, etc. After comparison, this formula gives an exact expression of the parameter $\beta$ of the modified Gibbs-Di Marzio equation.