title: Structural characterization of water and ice in mesoporous SBA-15 silicas IV: partially filled cases for 86 Å pore diameter.
abstract: 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 Å, 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.
authors.affiliation: Department of Physics, Faculty of Science, Vali-e-Asr University of Rafsanjan, Iran.
authors.forename: J
authors.initials: J
authors.lastname: Seyed-Yazdi
authors.forename: John C
authors.initials: JC
authors.lastname: Dore
authors.forename: J Beau W
authors.initials: JB
authors.lastname: Webber
authors.forename: H
authors.initials: H
authors.lastname: Farman
mesh_terms: D007053:Ice; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature
chemical_list: D007053:Ice; C509969:SBA-15; D012822:Silicon Dioxide