ROLE OF NETWORK CONNECTIVITY ON THE ELASTIC, PLASTIC AND THERMAL-BEHAVIOR OF COVALENT GLASSES

Experiments on chalcogenide glasses show that local elasticity as meas ured by Raman scattering and the kinetic heat-flow near T-g as establi shed from temperature modulated differential scanning calorimetry each display a threshold behavior associated with network connectivity as defined by the mean coordination, [r], near [r] = [r](c) similar or eq ual to 2.40. Network plasticity of amorphous group IV networks as dedu ced from nanometer-indentation hardness measurements varies linearly w ith [r] once [r] > 2.40. Consequences of these results connecting phys ical behavior of covalent networks with their connectivity are discuss ed. (C) 1997 Elsevier Science B.V.