科研之友
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摘要
Ptotons dynamics in borosilicate,glasses of various compositions (SiO2/B2O3/NaO/CaO/X,with X := Al2O3 or ZrO2) at-various Stages of alteration have been characterized at a picosecond scale using quasielastic neutron scattering (QENS). The results obtained were compared to the one from porous silica-based material (MCM41) having pore wall surfaces with Si OH, Al-OH, or Zr-OH terminal groups and pore sizes around 2.3 ran. The composition and the nanoporosity of the,alteration layers were characterized using solution analysis, small angle X-ray scattering and transmission electron microscopy. The strength hydrogen bonds of confined water were studied using thermogravimetric analysis and differential thermal analysis. The results showed that the free water bonding and the mobility of protons depend on the altered glass composition and that the residence time of water obtained from QENS analysis is apparently correlated to the alteration rate of the glass. Moreover, whereas the composition of the alteration layer can partially explain this result, the presence of ions in the leachate filling the gel nanoporosity seems to be the main factor affecting the water/protons mobility. The latter result is really important since the ion solvation and the ion adsorption on the surface can strongly impact the hydrolysis rate of the pore wall of the gel and can also modify the kinetics of dissolved elements recondensation into the banopore.
- 出版日期2015-7-16
- 单位中国地震局
