Sb-Based antiferromagnetic oxychlorides: MSb2O3(OH)Cl (M = Mn, Fe, Co) with 2D spin-dimer structures

Abstract

Three new Sb-based antiferromagnetic oxychlorides: MnSb₂O₃(OH)Cl (1), FeSb₂O₃(OH)Cl (2), and CoSb₂O₃(OH)Cl (3) have been synthesized by using hydrothermal reaction methods. Their crystal structures are isostructural and incorporate two types of structural units: sphenoid SbO₄ polyhedra and M₂O₈Cl₂ (M = Mn, Fe, Co) dimers, that share edges forming a two dimensional (2D) MSb₂O₃(OH)Cl network. The neutral MSb₂O₃(OH)Cl 2D layers are arranged from ABAB-type for compounds 1 and 2 to AA′B′B-type for 3 with smaller cation radii. Magnetic measurements show that 1 belongs to an antiferromagnetic material, while 2 and 3 have weak ferromagnetic properties with unsaturated ferromagnetism originating from spin-canting below the transition temperature. In addition, the optical absorption band gaps were determined to be 3.8, 2.4, and 3.6 eV for 1, 2, and 3, respectively. This work demonstrates that utilizing both halide ions and lone-pair elements simultaneously in one structure is a feasible and practical route to reduce framework connectivity in order to synthesize new low-dimensional oxyhalides.