Structural characterization of water and ice in mesoporous SBA-15 silicas IV: partially filled cases for 86 pore diameter

• Published in: Journal of physics. Condensed matter Vol. 25; no. 46; p. 465105
• Main Authors: Seyed-Yazdi, J, Dore, John C, Webber, J Beau W, Farman, H
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 20.11.2013; Institute of Physics
• Subjects: Chemistry; Colloidal state and disperse state; Condensed matter; Conversion; Diffusion; Exact sciences and technology; Formations; General and physical chemistry; Ice; Porosity; Porous materials; Scattering; Silicon dioxide; Silicon Dioxide - chemistry; Structural analysis; Temperature; Water; Confinement; Pore size; Parametric analysis; Supercooled liquid; Ice; Fill factor; Porous material; Silica; Diffuse scattering; Mesoporosity
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/46/465105

Previous papers in this series have involved the study of water/ice in a sample of a mesoporous SBA-15 silica with a pore size of 86 , filling-factors f of 1.15 and 0.95. The present paper extends the study to partially filled samples with f = 0.6 and 0.4. It is found that the ice formed in the pores has characteristics that differ markedly from those seen in the previous measurements. For f = 0.6, there is a significant amount of hexagonal ice, as seen by the presence of the normal ice triplet. For f = 0.4, the triplet peaks are not seen, indicating the predominant formation of cubic ice superimposed on a broad diffuse scattering peak that is attributed to a defective form of low-density amorphous ice. A parameter-fitting routine has been used (as previously) to extract the variation of the peak intensities and shapes with temperature. A separate component analysis procedure confirms these conclusions and emphasizes the role of plastic ice in the phase conversion process for the 260-200 K temperature region. A comparison of the liquid phase data for filling-factors of 0.4 and 0.95 indicates that the structural characteristics of the water vary according to the thickness of the layer, as suggested by computer predictions.