New Insulating Layered Network 3D-Ferromagnets Composed of the Divalent Metal Perrhenates: Fe(ReO4)2, Co(ReO4)2 and Ni(ReO4)2

A variety of a.c. and d.c. magnetrometry data as well as iron-57 Mossbauer spectra show that the structurally layered divalent metal perrhenates: M(ReO4)2 (M = Ni, Fe, Co) have three dimensional ferromagnetic ground states with Curie temperatures of 12.5K, 8.5K and 4.7K respectively. The nickel compound exhibits a substantial coercivity (∼ 0.26T) at 4.2K.