Studies of the Raman scattering from hydrogen and deuterium dissolved in vitreous silica at 90 °C and at pressures from 66 to 849 atm have been performed. The Raman spectra are interpreted to give information about the physics and thermodynamics of dissolution. In particular it is shown that: (1) hydrogen dissolves as a molecule, (2) the dissolved molecules occupy confining interstices and bind only weakly to the silica, and (3) the solubility saturates at higher pressures when the available interstices become filled. The results are explicable using classical thermodynamics and a physical rather than chemical model for dissolution.
The structures of the imidazole loaded derivatives of Al-MIL-53 [Al(OH)(1,4-BDC-(CH))] (x = 0, 1, 2) and CAU-11 ([Al(OH)(SDBA)]) (1,4-HBDC = terephthalic acid; HSDBA = 4,4'-sulfonyldibenzoic acid) were determined from powder X-ray diffraction data. Impedance spectroscopy measurements were carried out to evaluate their proton conductivities under anhydrous conditions at temperatures up to 110 °C. In Al-MIL-53-(CH)_HIm (x = 0, 1, 2) the formation of hydrogen bonds between the framework and the guest molecules results in a decrease in proton conductivity (x = 1.7 × 10, x = 1.9 × 10 and x = 1.7 × 10 S cm at 110 °C and E = 0.42, 0.41 and 0.46 eV, for 0, 1 and 2 CH-groups, respectively). The highest conductivity has been measured for CAU-11_HIm with 3.0 × 10 S cm at 110 °C (E = 0.19 eV), where no host-guest hydrogen bonding interactions are observed.
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