Control growth of NiFe2O4 phase in thermal annealed α-Fe2O3/NiFe2O4 nanocomposites for the beneficial magnetic application

Bimagnetic α-Fe2O3/NiFe2O4 nanocomposite was synthesized via a simple and cost-effective approach, and the effect of the annealing temperature on the nanocomposite properties was discussed. Structural characterizations confirm the formation of α-Fe2O3/NiFe2O4 nanocomposite. Transmission electron microscope (TEM) characterization reveals the bimodal distribution of particles in the nanocomposites. Thermal annealing favours for the improvement of phase fraction along with the structural phase transformation of NiFe2O4 phase. Existence of percolation threshold phase fraction of NiFe2O4 in the composite sample could be responsible for the enhancement of optical band gap and magnetization. Beyond the percolation phase fraction, the magnetization decreased along with the coercivity and exchange bias. The appearance of enhanced optical property, single domain structure, ferromagnetic behaviour and high-energy product suggests the usefulness of the sample for photocatalyst, magnetic sensor and magnetic refrigerator applications.