Perovskite-like Framework Encapsulated with Fe-Based Magnetic Units in Ba₁₀Fe₃Sb₇Se₂₄

Ba₁₀Fe₃Sb₇Se₂₄ was synthesized using a KBr flux at 850 °C (Crystal Data: orthorhombic, Cmc2₁, a = 9.3412(2) Å, b = 44.6666(10) Å, c = 12.5496(3) Å, V = 5236.2(2) ų, and Z = 4). The compound adopts a new three-dimensional framework constructed by the layer to include Fe₂Se₆ dimers and FeSe₄ tetrahedra in the linkage motifs of [Fe₂SbSe₁₀] and [FeSb₆Se₁₄], respectively. Alternatively, the all Sb-based polyhedra are assembled as a semiconducting, perovskite-like framework lacking an inversion center where these Fe-based magnetic units are trapped within the interstices. The strong antiferromagnetic interaction is revealed by a high Curie constant of -113 K, but the curvature of field-cooled and zero-field-cooled magnetic susceptibilities bifurcating at ∼19 K is observed. The critical temperature is well verified by a broad peak of χ_M″ signal showing a rapid increase below 19 K under an alternating current field. The Fe₂Se₆ dimer featuring distorted edge-sharing tetrahedra to induce the spin-canted antiferromagnetic ordering strongly dominates such magnetic ordering. Finally, a weak hysteresis loop is clearly observed at 2.0 K. This dilute magnetic selenide displays a direct bandgap at ∼1.54 eV, analyzed by the Tauc equation. Interestingly, the use of second-harmonic-generation temperature dependence shows a turning point at ∼20 ± 1 K, which precisely corresponds to the magnetic ordering temperature within the error bar, thereby demonstrating the versatility of the technique for probing magnetic phase transition.