Magnetic properties of Mg/Co(II)–Al/Fe(III) layered double hydroxides

Abstract Mg/Co–Al/Fe–CO 3 layered double hydroxides were synthesized by coprecipitation reaction method. According to powder X-ray diffraction (Cu–Kα) and scanning electron microscopy, all the samples exhibit hydrotalcites with layered double structure. Onefold Co 2 + or Fe 3 + doping does not show ferromagnetism. Room temperature ferromagnetism can be obtained by Co 2 + and Fe 3 + codoping, on the condition that more than 50% of Mg 2 + and Al 3 + are substituted by Co 2 + and Fe 3 + , respectively. The coaction of different magnetic interactions leads the macroscopic ferromagnetism of the samples. The ferromagnetic coupling of Co 2 + –O 2− –Co 2 + results in the ferromagnetism of brucite-like layers and the antiferromagnetic coupling of Co 2 + –O 2− –Fe 3 + enhances the magnetism of the interlayers.