Sharp rigid to floppy phase transition induced by dangling ends in a network glass - art. no. 185503

The,count of Lagrangian bonding constraints n(c)(y) in ternary Ge25S75-yIy glasses (0 < y < 0.30) is established from the molecular structure using Ra man scattering and first-principles cluster calculations. The results show that n(c)(y) decreases to 3 as y increases close to y(c) = 0.162(3), where a sharply defined global minimum in the nonreversing heat flow, DeltaH(nr)( y) near T-g is observed in scanning calorimetry. Here we have a rigidity tr ansition induced by I dangling ends, with its sharpness resulting from the absence of self-organization in the random network.