Crystal and Magnetic Structures of Monoclinic FeOHSO4.

The crystal and magnetic structures and properties of the monoclinic form of the iron hydroxysulfate FeOHSO4 were investigated by magnetometry and neutron powder diffraction. The space group C2/c was confirmed, and the proton position was located close to that predicted by ab initio calculations. The collinear antiferromagnetic k(0,0,0) structure forming below the Néel temperature TN ∼ 125 K is described by the C2'/c' (No. 15.89) magnetic space group, with the moments along the b axis. Overall, FeOHSO4 is isostructural to FeSO4F in terms of both the crystal and magnetic structures.