MIOF (M = Co and Ni): Magnetic Iodate Fluorides with Zigzag Chains.

The iodate anion group has been widely used for design and synthesis of functional materials including nonlinear optical materials but rarely for magnetic materials. Particularly, none of magnetic iodate fluorides has been reported yet. In this work, first, two novel magnetic iodate fluorides MIOF (M = Co and Ni ) have been synthesized by a hydrothermal method and characterized by magnetic susceptibility, magnetization, and heat capacity measurements as well as thermogravimetry, Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy. Compounds and are isostructural and crystallize in the monoclinic space group 2/ with alternating M-F-M-O-M zigzag spin chains along the axis, which are further separated by triangular IO groups in the plane. Magnetic susceptibilities suggest that exhibits an antiferromagnetic long-range order (LRO) at 16.5 K, confirmed by heat capacity results with released entropy consistent with the theoretical value for a pseudo-spin of 1/2 for Co at low temperatures. Meanwhile, displays a broad maximum around 10.5 K for low dimensional magnetism followed by a sharp peak at 5.7 K indicating the occurrence of an LRO transition, in good agreement with the heat capacity measurement. Field-dependent magnetizations show an obvious spin-flop transition around 4.5 T and a magnetic hysteresis loop between 4.5 and 7 T for , but only a slight slope change could be observed around 2.3 T for . Thermal stability, FT-IR, and UV-vis-NIR spectroscopy of and are also reported.