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Localization of Hydrogen and Content of Oxonium Cations in Alunite via Neutron Diffraction
Author(s) -
Schukow, H.,
Breitinger D. K.,
Zeiske Th.,
Kubanek F.,
Mohr J.,
Schwab R. G.
Publication year - 1999
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199906)625:6<1047::aid-zaac1047>3.0.co;2-f
Subject(s) - crystallography , neutron diffraction , chemistry , oxonium ion , rietveld refinement , crystal structure , ion , organic chemistry
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/σ(I) > 1) = 172, N (Var.) = 19, R p = 0.036, wR p = 0.046, R B (I/σ(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.