Physical Properties Evolution in Network Glasses of Ge–Cd–Se System: A Theoretical Approach
M. A. Dabban1*, Sarah. M. Al-Khadher2, Esam M. G. Al-Badwi2
الملخص
In technology, Ge-Se-Cd is a prototypical chalcogenide system capable of forming glasses on various components. A theoretical analysis was conducted to determine the effect of Ge-addition on the physical parameters of GexCd10Se90-x (x=5, 10, 15, 20 and 25 at. %) glasses systems. The values of the average coordination number, the number of constraints, the average heat of atomization, cohesive energy, density, and packing density were increased with an increase in the Ge content, while the values of lone pair electrons were decreased as the system was moving towards the rigid region. Deviation of the stoichiometry values leads the system to chalcogen-rich regions, except for Ge25Cd10Se65 indicating chalcogen-poor composition. A linear correlation was found between the overall mean bond energy and glass transition temperature. Increasing the Ge content leads to an increase in strong heteropolar Ge-Se bonds at the expense of weak homopolar Se-Se bonds, resulting in an increase in network connectivity or the rigidity of the system. The chemical order network model (CONM) was applied to calculate the distribution of the chemical bonds and the cohesive energy of the system. According to the Neffati relation, the theoretical band gap has been calculated. The increase in the energy gap with increasing Ge concentration for all systems except Ge25Cd10Se65 suggests that the 2D layered structure generated by the branching of the Se chain is completely established at this composition at
تحميل البحث