| Direct evidence of rigidity loss and self-organisation in silicate glasses (2004) | |||||||||
Abstract | |||||||||
| The Brillouin elastic free energy change $DF$ between thermally annealed and quenched $(Na_2O)_x(SiO_2)_{1-x}$ 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.. Comment: 12 pages RevTeX, 4 figures in EPS | |||||||||
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