%0 Conference Proceedings
%T Effect of stress gradient at the vicinity of a crack tip on ionic diffusion in silicate glasses : an AFM study
%+ Laboratoire des colloïdes, verres et nanomatériaux (LCVN)
%A Celarie, F.
%A Ciccotto, Matteo
%A George, Matthieu
%A Marliere, Christian
%< avec comité de lecture
%Z 07-018
%B The Fifth Conference on the Fractography of Glasses and Ceramics
%C Rochester, United States
%Y James R. Varner J.; Quinn G.; Wightman M.
%I wiley
%P 35
%8 2006-06-09
%D 2006
%K stress gradient
%K silicate glasse
%K AFM study
%K Ionic Diffusion
%K Soda−lime−silica Glass
%K Crack Growth
%K Atomic Force Microscopy
%Z PACS: 62.20.Mk; 66.30.-h; 68.03.Cd; 68.37.Ps
%Z Engineering Sciences [physics]/MaterialsConference papers
%X The slow advance of a crack in sodo-silicate glasses was studied at nanometer scale by in-situ atomic force microscopy (AFM) in a well-controlled atmosphere (N2 and H2O). An enhanced diffusion of sodium ions in the stress-gradient field at the sub-micrometric vicinity of the crack tip was revealed through several effects: growth of nodules in height images, changes in the AFM tip–sample energy dissipation as detected in phase images. Ex-situ chemical micro-analyses completed the AFM measurements. The nodules patterns revealed a dewetting phenomenon evidenced by “breath figures”, i.e. analog to the fogging that occurs when a vapour condenses onto a 'cold' surface [D. Beysens et al., Phys. Rev. Let. 57, 1433 (1986)]. These experimental results were explained by a two-step process: i) a fast migration of sodium ions towards the fracture surfaces as proposed by Langford et al. [J. Mat. Res. 6, 1358 (1991)], ii) a slow backwards diffusion of the cations as evidenced in these AFM experiments (typical time: few minutes). Measurements of the diffusion coefficient of that relaxing process were done at room temperature. Our results strengthen the theoretical concept of a near-surface structural relaxation due to the stress-gradient at the vicinity of the crack tip. Raman and SIMS studies revealed that nodules – for samples studied after exposition to common air - are preferentially covered by an organic overlayer of a carboxylate salt with a long aliphatic chain. The catalytic role of sodium ions in that chemical process is suspected.
%G English
%L hal-00408605
%U https://hal.science/hal-00408605
%~ CNRS
%~ UNIV-MONTP2
%~ LCVN
%~ AGROPOLIS
%~ UNIV-MONTPELLIER
%~ UM1-UM2