Geometrically frustrated materials are highly sought for their unique magnetic ground states and interesting physical properties. Inverse weberites are of interest as geometrically frustrated magnetic materials due to their unique cation arrangement. We have synthesized nine isostructural materials that adopt the inverse weberite crystal structure, which consists of cross-linked kagome layers. These materials, having the general formula MIIMIIIF5(H2O)2 (MII = Co, Mn, Ni, and Zn; MIII = Ga, Cr, Fe, and V), were synthesized using mild hydrothermal conditions, which yielded phase pure samples after reaction conditions optimization. Their crystal structures, optical, thermal, and magnetic behavior were characterized using single crystal X-ray diffraction, UV-vis spectroscopy, thermogravimetric analysis, and by measuring the magnetic susceptibility and isothermal magnetization data respectively. The materials exhibit excellent tunability in optical properties due to the variety of 3d metals that can be integrated into the structure. Three distinct types of magnetism were observed including simple paramagnetism, antiferromagnetism, and canted antiferromagnetism, the latter is accompanied with a high frustration index f in a range 4.16–8.09. We demonstrated that the magnetic behavior of inverse weberites depends on the presence or absence of unpaired electron containing cations on the two distinct crystallographic sites, which can be employed for the prediction of the magnetic properties of other compounds in this rich and diverse family.

Geometrically frustrated family of MIIMIIIF5(H2O)2 mixed–metal fluorides with complex magnetic interactions

ACS Spring 2022

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