Deformations of the α‐Fe 2 O 3 rhombohedral lattice across the Néel temperature

High‐resolution synchrotron radiation powder diffraction patterns of α‐Fe 2 O 3 measured between room temperature and 1100 K, i.e. above the Néel temperature T N = 950 K, have been analyzed. The integral breadths of the Bragg peaks show a hkl ‐dependent anisotropy, both below and above T N . This anisotropy can be quantitatively described by using a statistical peak‐broadening model [Stephens (1999). J. Appl. Cryst. 32 , 281]. Model calculations show that the rhombohedral α‐Fe 2 O 3 lattice is deformed and the deformation leads to a monoclinic lattice with the unique monoclinic axis along the hexagonal [110] direction both below and above T N . The monoclinic symmetry of bulk α‐Fe 2 O 3 is compatible with α‐Fe 2 O 3 nanowire growth along the [110] direction reported in Fu et al. [ Chem. Phys. Lett. (2001), 350 , 491].