Contrasting Magnetic Structures in the Quaternary Sulfides Ba 2 FeMS 5 (M = Sb, Bi)

Journal article

Ba2FeSbS5 and Ba2FeBiS5 are two isostructural quaternary sulfides that crystallize in the Pnma space group with four formula units per unit cell. Ba2FeSbS5 has lattice parameters a = 12.08609(3) Å, b = 8.83426(2) Å, and c = 8.89114(2) Å, and Ba2FeBiS5 has a = 12.09610(3) Å, b = 8.89281(2) Å, and c = 8.82437(2) Å at room temperature. They comprise infinite [FeMS5]4– (M = Sb, Bi) chains, where Fe3+ is present in FeS4 tetrahedra and M3+ ions reside in edge-sharing MS6 distorted octahedra, each of which shares an edge with an FeS4 tetrahedron. Powder neutron diffraction measurements confirm the presence of long-range antiferromagnetic order of the Fe3+ moments in both materials, where Fe–S···S–Fe super-superexchange interactions which act along the direction of the [FeMS5]4– (M = Sb, Bi) chains are the driving force for this antiferromagnetic order. The magnetic Bragg reflections reside on a k-vector with k = (1/2 0 1/2), and the relative orientations of the moments are similar in the two cases One significant difference is that the moments are aligned along the crystallographic b-axis in Ba2FeSbS5, whereas in Ba2FeBiS5 they lie along the longer crystallographic a-axis, reflecting the weak directional preference of the Fe3+ moments. Furthermore, an additional incommensurately modulated ordering of the Fe3+ moments is suggested for Ba2FeSbS5 (but not Ba2FeBiS5) by the appearance of small additional magnetic Bragg peaks in the neutron diffraction data, which may be a consequence of greater magnetic frustration in Ba2FeSbS5.

Authors: Sheath, BC; Savvin, S; Clarke, SJ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Inorganic Chemistry
• Volume: 63
• Issue: 49
• Pages: 23267-23275
• Publication date: 2024-11-25
• Acceptance date: 2024-11-07
• DOI: 10.1021/acs.inorgchem.4c03770
• EISSN: 1520-510X
• ISSN: 0020-1669
• Language: English