paper

Direct evidence of rigidity loss and self-organisation in silicate glasses

arXiv:cond-mat/0406509

Abstract

The Brillouin elastic free energy change $D F$ between thermally annealed and quenched $(N a_{2} O)_{x} (S i O_{2})_{1 - x}$ glasses is found to decrease linearly at $x > 0.23$ (floppy phase), and to nearly vanish at $x < 0.18$ (stressed- rigid phase). The observed $D F (x)$ variation closely parallels the mean-field floppy mode fraction $f (x)$ in random networks, and fixes the two (floppy, stressed-rigid) elastic phases. In calorimetric measurements, the non-reversing enthalpy near $T_{g}$ is found to be large at $x < 0.18$ and at $x > 0.23$ , but to nearly vanish in the $0.18 < x < 0.23$ range, suggesting existence of an intermediate phase between the floppy and stressed-rigid phases.

12 pages RevTeX, 4 figures in EPS