Elastic/Plastic Behavior of Chalcogenide Glasses in the Ge-Sb-Se System

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Alfred University. Faculty of Ceramic Engineering. Kazuo Inamori School of Engineering
Elastic/plastic behavior of chalcogenide glasses in the Ge-Se and Ge-Sb-Se systems was studied using different spherical indenters: 400μm and 2mm. Static room temperature indentations were carried out to determine the trends in hardness, fracture toughness and brittleness with respect to the average covalent coordination number, <r>. Binary glasses show maximization in fracture toughness and minimization in brittleness at the composition Ge_{20}Se_{80}. No such trends were observed for ternary glasses. Indentations were also performed at -80°C to ensure that the trends are due to structural considerations of optimized connectivity. LBH and elastic modulus increase linearly with the network connectivity. Elastically recovered energy increases with indenter diameter showing a local maximum at Ge_{20}Se_{80}. Finite element simulations of binary glasses also show similar trends for LBH and DBH. Increasing elastic moduli cause stresses to increase with <r> for a given indenter ball diameter. Computed yield stresses, when plotted against <r>, show small deviations from apparent linearity at <r> = 2.4, giving another hand to the theory of rigidity percolation.
Plasticity, Chalcogenide glasses, Selenium, Germanium, Elasticity, Antimony