Boric acid flux synthesis, structure and magnetic property of MB12O14(OH)10 (M=Mn, Fe, Zn)

KMB4O6F3 (M = Co, Fe): two-dimensional magnetic fluorooxoborates with triangular lattices directed by triangular BO3 units

Frustrated magnetic systems are of great interest owing to their spin liquid state for application in quantum computing. However, experimentally, spin liquid has not been realized. Thus, experimental explorations of frustrated magnetic systems including triangular lattices are still urgent, particularly for directed synthesis compared to random exploration. Herein, for the first time, directed by the use of a triangular unit of the BO3 anion group, two novel layered magnetic fluorooxoborates KMB4O6F3 (M = Co 1, Fe 2) with triangular lattices have been hydrothermally synthesized and characterized. Compounds 1 and 2 are isostructural and crystallize in the P21/c space group with layered magnetic triangular lattices, which are further separated by K+ ions. Magnetic susceptibility curves of both 1 and 2 show no λ-anomaly peak down to a low temperature of 2 K in the absence of a magnetic long-range ordering transition, which are further confirmed by the heat capacity results. The magnetic-field dependence of magnetization at 2 K shows saturation of 2.20μB for 1 and 4.24μB for 2, respectively, at 7 T, after roughly subtracting the Van Vleck paramagnetic contribution. Further in-depth investigation of the underlying physics at a lower temperature below 2 K would be subsequently performed. Moreover, thermal stability and FT-IR and UV-vis-NIR spectroscopy with optical bandgap properties are also reported. Most importantly, our work provides a promising method to experimentally realize specific magnetic lattices (e.g. triangular lattices) directed by the use of triangular groups (e.g. BO3) as the functional unit.

Hydrated Zinc Borates and Their Industrial Use

Zinc borates are important chemical products having industrial applications as functional additives in polymers, bio-composites, paints and ceramics. Of the thirteen well documented hydrated binary zinc borates, Zn[B₃O₄(OH)₃] (2ZnO∙3B₂O₃∙3H₂O) is manufactured in the largest quantity and is known as an article of commerce as 2ZnO∙3B₂O₃∙3.5H₂O. Other hydrated zinc borates in commercial use include 4ZnO∙B₂O₃∙H₂O, 3ZnO∙3B₂O₃∙5H₂O and 2ZnO∙3B₂O₃∙7H₂O. The history, chemistry, and applications of these and other hydrated zinc borate phases are briefly reviewed, and outstanding problems in the field are highlighted.