Microhardness, indentation toughness, elasticity, plasticity, and brittleness of Ge–Sb–Se chalcogenide glasses

Elastic/plastic properties of Ge–Se binary and Ge–Sb–Se ternary chalcogenide glasses were explored by indenting with Vickers and Brinell (spherical) microindenters using static and ‘instrumented’ (load versus penetration) recording machines and analyzed further using a non-contact profilometer. The load-dependence of microhardness, indentation fracture toughness and brittleness versus the average covalent coordination number, 〈r〉, were studied. It is concluded that the elastic recovery of deformations is maximized at ∼GeSe4 (〈r〉 = 2.4), which is consistent with ‘optimized connectivity’ of the rigidity percolation arguments. Surprisingly, many of the extrema were nearly non-existent in the ternary glasses.