Correlation of the glass transition temperature and average energetic connectivity in network chalcogenide glasses

A correlation ratio between a glass transition temperature Tg and average bond energy E (obtained for chalcogenide glasses in L. Tichý & H. Tichá [J. Non-Cryst. Solids, 189, 1995]) was critically analyzed in this paper. As a result, this ratio was shown to have been obtained using incorrect calculations of the average bond energy E through inappropriate application of different averaging procedures for different terms of this parameter and, therefore, it cannot be used in practice. A mathematical algorithm for calculating the average energy bonding was adjusted by the atom-averaging procedure for the both energy of the “network part of a matrix” Ec (energy of heteropolar bonds) and energy of a "residual matrix" Erm (energy of homopolar bonds), as well as considering the impossibility of forming covalent chemical bonds between cations of different type. It was stated that the linear ratio between the glass transition temperature Tg and energy bonding E can be obtained by the ratio Tg ≅ 326∙(E – 0.94) and this claim was proved for 145 typical representatives of the covalent-bonded network chalcogenide glasses (Ge-As-S/Se-type systems).