Positron annihilation lifetime spectroscopy is employed to measure the size of the interstitial void spaces characterizing the structure of a set of permanently densified SiO2 glasses. The average volume of the voids is markedly affected by the densification process and linearly shrinks by almost an order of magnitude after a relative density variation of 22%. In addition, x-ray diffraction shows that this change of density does not modify appreciably the short range order, which remains organized in SiO4 tetrahedra. These results strongly suggest a porous medium description for v-SiO2 glasses where the compressibility and the medium range order are dominated by the density variation of the voids volume up to densities close to that of α-quartz.
Structural Evolution and Medium Range Order in Permanently Densified Vitreous SiO_2 / Zanatta, Marco; Baldi, Giacomo; Brusa, Roberto Sennen; Egger, W.; Fontana, Aldo; Gilioli, E.; Mariazzi, Sebastiano; Monaco, Giulio; Ravelli, Luca; Sacchetti, F.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 112:4(2014), pp. 045501-1-045501-5. [10.1103/PhysRevLett.112.045501]
Structural Evolution and Medium Range Order in Permanently Densified Vitreous SiO_2
Zanatta, Marco;Baldi, Giacomo;Brusa, Roberto Sennen;Fontana, Aldo;Mariazzi, Sebastiano;Monaco, Giulio;Ravelli, Luca;
2014-01-01
Abstract
Positron annihilation lifetime spectroscopy is employed to measure the size of the interstitial void spaces characterizing the structure of a set of permanently densified SiO2 glasses. The average volume of the voids is markedly affected by the densification process and linearly shrinks by almost an order of magnitude after a relative density variation of 22%. In addition, x-ray diffraction shows that this change of density does not modify appreciably the short range order, which remains organized in SiO4 tetrahedra. These results strongly suggest a porous medium description for v-SiO2 glasses where the compressibility and the medium range order are dominated by the density variation of the voids volume up to densities close to that of α-quartz.File | Dimensione | Formato | |
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