Petersen, Hilke
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Item-typ:Veröffentlichung, 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.Wissenschaftlicher Artikel268 315 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Synthesis and characterization of new sodalites, cancrinites and their intermediate phase(2018-11-19); ; ; The thermal behavior and occuring phase transitions of three sodalites, a permanganate-, a perrhenate and a mixed permanganate/perrhenate-sodalite are investigated. Below 300 K a loss of dynamic motion of the templating anions could be observed, causing a phase transition of perrhenate-sodalite. At elevated temperatures all sodalites show a phase transition to the fully expanded structure (P-43n to Pm-3n). At 900 K the permangante-sodalite shows a second phase transition to P23.Further a comprehensive study on cancrinites containing different divalent tetrahedral coordinated anions (XO4 2-; X = Mn, Cr, Se, Mo, W) and their effect on the thermal behavior is performed. Thirdly, a structural investigation of the one-dimensional disordered Intermediate phase is carried out. By correlating the lattice parameter c with the existing zeolite-cages and the chemical composition of the sample the structure of the intermediate phase could be modeled.Dissertation402 222