The structure of Fe(OHb>0.86b>,ODb>0.14b>)b>2b> was refined by applying the Rietveld technique to neutron powder diffraction data collected at 300, 150, and 10 K. The nuclear structure, of the CdIb>2b> type (P3̅m1) and isostructural with Mg, Ca, Mn, Ni, and β-Co(OH)b>2b>, is maintained over the range of temperatures studied. At 10 K, the magnetic structure is ordered antiferromagnetically, with the magnetic moments aligned in the basal plane. The refined Fe2+ magnetic moment magnitude is 3.50(4) μb>Bb>. This magnetic structure (space group Pb>2cb>1−) is unique amongst those encountered in the transition metal dihydroxides, for which the moment is either directed along the c axis [β-Co(OH)b>2b> and Ni(OH)b>2b>], or at least has a considerable component along this direction [Mn(OH)b>2b>]. The dependence of the strength of potential hydrogen bonds with temperature is discussed.
