Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 45: Nanostructured Materials VI

MM 45.1: Talk

Thursday, February 28, 2008, 15:00–15:15, H 0111

Analysis of sorption strains in mesoporous silica by in-situ x-ray diffraction — •Johannes Prass, Dirk Müter, John Dunlop, Stefan Siegel, Chenghao Li, and Oskar Paris — Max Plank Institut für Kolloid und Grenzflächenforschung, 14424 Potsdam, Germany

Sorption and capillary condensation of fluids in ordered mesoporous silica ( SBA-15 and MCM-41) were studied by in situ small-angle X-ray diffraction using synchrotron radiation. Diffraction peaks resulting from the pore lattice were evaluated in terms of lattice strains. Intensity, position and width of the diffraction peaks show pronounced changes in the capillary condensation/evaporation regime. At complete pore filling, an expansion of the lattice is observed which can be explained by the decrease of total interfacial energy. A contraction of the pore lattice is observed for the nearly filled pores for both branches of the sorption isotherm, which is attributed to liquid menisci due to capillary condensation of fluid in the pores. Data measured for fluids with different surface tension and silica materials with different pore width allow to vary elastic strains in the pore lattice and to compare them with simple models.