Effect of high magnetic field annealing on the microstructure and magnetic properties of Co–Fe layered double hydroxide

The effects of high magnetic field (10 T) on the products obtained by calcination of Co–Fe LDH precursors at different temperatures were investigated. The XRD results indicated that FeIII substituted for CoIII in Co3O4 to yield CoIICoIIIFeIIIO4 under the calcination of Co–Fe LDH precursors at 400 °C. The products obtained by magnetic field annealing at 400 °C had a porous plate-like morphology, whereas the products without magnetic field annealing were composed of nanoparticles. It was seen that CoFe2O4 phase could be formed at low temperature (about 500 °C) under the magnetic field annealing. The grain size of products obtained by magnetic field annealing at 800 °C was larger than that of zero magnetic field. It was found that the saturation magnetization was significantly enhanced after magnetic field annealing, especially at lower temperature (≤600 °C). The possible reason for the effects on the microstructure and magnetic properties of products obtained by magnetic field annealing was discussed.