Molecular structure of the uranyl mineral zippeite - An XRD, SEM and Raman spectroscopic study
Frost, Ray L.; Weier, Matt L.; Bostrom, Thor; Čejka, Jiří Martens
published: Jun 9, 2005
ArtNo. ESP154018103006, Price: 29.00 €
Raman spectra at 298 and 77 K and infrared spectra of the uranyl sulfate mineral zippeite, K2[(UO2)6(SO4)3O(OH)6 ] Â· 4H2O, were studied. Observed bands were tentatively attributed to the (UO2)2+ and (SO4)2- stretching and bending vibrations, the OH stretching vibrations of water molecules and hydroxyls, H2O bending vibrations and libration modes, and Î´ UÂOH bending vibrations. Empirical relations were used for calculation of UÂO bond lengths in uranyl R = f(ν3 or ν1 (UO2)2+) Ã . This was found in agreement with UÂO bond lengths from the single crystal structure analysis. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U6+ (in uranyl) and S6+ (in sulfate), and water molecules and hydroxyls may be present in the zippeite crystal structure. Some OÂHÂ O bond lengths were attributed to the hydrogen-bonding network in zippeite crystal structure.