The nuclear and magnetic structure of “white rust”—Fe(OH 0.86 D 0.14 ) 2

The structure of Fe(OH 0.86 ,OD 0.14 ) 2 was refined by applying the Rietveld technique to neutron powder diffraction data collected at 300, 150, and 10 K. The nuclear structure, of the CdI 2 type (P3̅ m1) and isostructural with Mg, Ca, Mn, Ni, and β-Co(OH) 2 , 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 Fe 2+ magnetic moment magnitude is 3.50(4) μB. This magnetic structure (space group P 2c 1̅) is unique amongst those encountered in the transition metal dihydroxides, for which the moment is either directed along the c axis [b-Co(OH) 2 and Ni(OH) 2 ], or at least has a considerable component along this direction [Mn(OH) 2 ]. The dependence of the strength of potential hydrogen bonds with temperature is discussed.