Localization of Hydrogen and Content of Oxonium Cations in Alunite via Neutron Diffraction

✍ Scribed by H. Schukow,; D. K. Breitinger; Th. Zeiske; F. Kubanek; J. Mohr; R. G. Schwab

• Book ID: 101305116
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: German
• Weight: 106 KB
• Volume: 625
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/(sici)1521-3749(199906)625:6<1047::aid-zaac1047>3.0.co;2-f

✦ Synopsis

Polycrystalline alunite-d 6 KAl 3 (OD) 6 (SO 4 ) 2 , prepared by hydrothermal reaction of Al 2 (SO 4 ) 3 , K 2 SO 4 and D 2 SO 4 , was studied by neutron powder diffraction performed on the diffractometer E2 (HMI-BENSC, Berlin). Rietveld refinement of the data set for T = 2 K yielded the crystallographic data: space group R3m, Z = 3, trigonal setting, a = 694.3(1) pm, c = 1722.7(2) pm, N(I/r(I) > 1) = 172, N(Var.) = 19, R p = 0.036, wR p = 0.046, R B (I/r(I) > 1) = 0.020. The deuterium nuclei could be located precisely. Three equivalent O±D bonds with nuclear distances r(O(4)±D) = 96.6(3) pm directed to each of the terminal oxygen atoms of the SO 4 groups are found. Partial substitution of K + by D 3 O + was also considered in the refinement procedure. In good agreement with results of other methods a site occupation fraction n(D 3 O + ) = 0.0104 was obtained.