Effect of the Synthesis Method on the Phase Composition and Magnetism of Layered Double Hydroxides

A number of tetrametallic layered double hydroxides containing magnesium and cobalt on the site of doubly charged cations in the structure of brucite-like layers and aluminum and iron on the site of triply charged cations have been synthesized using three distinct methods: coprecipitation, microwave synthesis, and hydrothermal crystallization. A sodium hydroxide solution was used as a precipitant. The results demonstrate that all three methods yield a well-crystallized hydrotalcite-like layered hydroxide and an impurity phase. We believe that it is the impurity phase which is responsible for the magnetism of the materials. Most likely, this phase is spinel CoFe 2 O 4 .