Deformations of the α-Fe₂O₃ rhombohedral lattice across the Néel temperature

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• 作者：P. Fabrykiewicz ; M. Stękiel ; I. Sosnowska and R. Przeniosło
• 关键词：N&eacute ; el temperature ; high-resolution synchrotron powder diffraction ; peak-broadening ; ferromagnetism
• 刊名：Acta Crystallographica Section B
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：73
• 期：1
• 页码：27-32
• 全文大小：457K
• ISSN：2052-5206

文摘

High-resolution synchrotron radiation powder diffraction patterns of α-Fe₂O₃ 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-Fe₂O₃ 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-Fe₂O₃ is compatible with α-Fe₂O₃ nanowire growth along the [110] direction reported in Fu et al. [Chem. Phys. Lett. (2001), 350, 491].