Ba3FeS4Br: A 0D Iron-Based Chalcohalide with Unusual Magnetic Properties

Abstract

A new 0D iron-based magnetic chalcohalide, Ba₃FeS₄Br, has been prepared by the spontaneous crystallization method. It crystallizes in the orthorhombic space group Pnma. Interestingly, the structure contains a Ba–Br reticulate structure in which isolated FeS₄ tetrahedra are located. Its band gap was experimentally determined to be 1.65 eV. Despite the large separation between the Fe atoms, with the shortest distance being more than 6.33(2) Å, temperature-dependent magnetic susceptibility and field-dependent magnetization measurements on Ba₃FeS₄Br unexpectedly showed an antiferromagnetic phase transition at 85 K, which may be due to the antiferromagnetic super exchange of Fe³⁺ spins.

Ba₃FeS₄Br features discrete covalent FeS₄ tetrahedra located within the ionic Ba–Br framework. Despite the large separation between the Fe atoms, with the shortest distance being more than 6.33(2) Å, Ba₃FeS₄Br unexpectedly exhibits an antiferromagnetic phase transition at 85 K, which may due to the antiferromagnetic super–super exchange of Fe³⁺ spins.

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