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

• Mg/Co–Al/Fe–CO3 LDHs were synthesized by coprecipitation reaction method.
• The Mg–Al LDHs samples with onefold Co2 + or Fe3 + doping are paramagnetic.
• Room temperature ferromagnetism can be obtained by Co2 + and Fe3 + codoping.
• The specific effects and mechanism of Co2 + and Fe3 + doping were discussed in detail.

Mg/Co–Al/Fe–CO3 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 Co2 + or Fe3 + doping does not show ferromagnetism. Room temperature ferromagnetism can be obtained by Co2 + and Fe3 + codoping, on the condition that more than 50% of Mg2 + and Al3 + are substituted by Co2 + and Fe3 +, respectively. The coaction of different magnetic interactions leads the macroscopic ferromagnetism of the samples. The ferromagnetic coupling of Co2 +–O2−–Co2 + results in the ferromagnetism of brucite-like layers and the antiferromagnetic coupling of Co2 +–O2−–Fe3 + enhances the magnetism of the interlayers.

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