Synthesis of highly dispersed ferromagnetic materials based on layered lithium aluminum hydroxides and nickel and cobalt particles

The reaction between a concentrated aqueous lithium nitrate solution and a cobalt-containing composite prepared through the thermal decomposition of [LiAl2(OH)(6)](2)[CoEDTA] center dot 4H(2)O in vacuum at temperatures from 400 to 500 C has been studied using x-ray diffraction and chemical analysis. The results indicate that, first, the lithium-aluminum-oxygen species present in the composite react with water molecules in the lithium nitrate solution to form layered Li-Al hydroxides. The next step is a hydroxide for nitrate ion exchange, leading to the formation of a nitrate form of the hydroxides. A similar mechanism underlies the formation of a nitrate in the reaction between nickel-containing composites and aqueous lithium nitrate. The nickel-and cobalt-containing composites prepared via vacuum thermolysis of [LiAl2(OH)(6)](2)[MEDTA] center dot 4H(2)O (M = Ni, Co) react with water to form a ferromagnetic carrier containing, in addition to a metallic phase, an aluminum lithium hydroxide and bayerite impurity.