Robben, Lars
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Item type:Publication, Disordered but primitive gallosilicate hydro-sodalite: Structure and thermal behaviour of a framework with novel cation distribution(2018-01-15); ; ; ; The structure of a new gallosilicate sodalite |Na6.16(1)(H2O)8|[Ga1.04(1)Si0.96(1)O4]6 described in space group with lattice parameter a = 885.208(7) pm is reported. For such a sodalite with a deviation from a 1:1 ratio in the framework cations a body-centred structure in space group could be expected. The structure shows structural stress resulting from this unusual substitution by a high strain visible in reflections which are forbidden by symmetry in . Distinct amounts of Ga and Si are redistributed on the opposite crystallographic position. The second coordination sphere of Si was examined by 29Si MAS NMR, the absence of OH− in the sodalites cages was checked by FTIR- and Raman spectroscopy. The intensity distribution of MAS NMR signal is modelled using a new technique to calculate the framework metal second neighbour coordination. The confirmed distribution leads to a low thermal stability of the cubic sodalite indicated by a new intermediated phase which could be regarded as a triclinic distorted cancrinite with three-time increased c lattice parameter. This intermediate phase decomposes at around 1000 K to a beryllonite-type sodium gallosilicate.journal article268 314 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Structural and spectroscopic comparison between polycrystalline, nanocrystalline and quantum dot visible light photo-catalyst Bi 2 WO 6The structural and spectroscopic features of the visible light photocatalyst Bi2WO6 have been studied. Polycrystalline (PC), nanocrystalline (NC) and quantum dot (QD) sized samples were produced using solid state reaction, hydrothermal and flame spray pyrolysis methods, respectively. While the crystal structures of PC and NC Bi2WO6 are well characterized using X-ray powder diffraction data Rietveld refinements, the structural information of the QD are obtained from the complementary pair distribution function analysis and high-resolution transmission electron microscopy. The Raman spectra of the samples are compared with the phonon density of states calculated by DFT. A continuous phenomenological model describes selective optical phonon confinement into the QDs. The type of the electronic bandgaps obtained from the UV-VIS absorbance-spectra have been analyzed using two different methods, and compared with those calculated from the electronic band structures.journal article520 451