Acta Cryst. (2013). E69, i84
[ doi:10.1107/S1600536813031619 ]
Abstract: The crystal structure of strontium diarsenate has been reinvestigated from single-crystal X-ray diffraction data. In contrast to the previous determinations of this structure [Weil et al. (2009). Solid State Sci. 11, 2111-2117; Edhokkar et al. (2012). Mater. Sci. Eng., 28, 012017] and to all isotypic A2B2O7 compounds that crystallize in the space group P41, the current redetermination revealed the P43 enantiomorph of Sr2As2O7 with a purity of 96.3 (8)%. The crystal structure is made up from two eclipsed As2O7 diarsenate groups (symmetry 1) with characteristically longer As-O bridging bonds [1.756 (4)-1.781 (4) Å] than the terminal As-O bonds [1.636 (4)-1.679 (4) Å] and four Sr2+ sites with coordination numbers ranging from seven to nine. The building units are arranged in sheets parallel to (001).
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