Synergy-induced enhancement of magnetic properties in α-Fe2O3/Ni1+xFe2-xO4 nanocomposites: role of Ni2+ and annealing temperature

The effect of thermal annealing on the structural, optical and magnetic properties of alpha-Fe2O3/Ni1+xFe2-xO4 (x = 0.05 and 0.10) nanocomposites was probed through different characterization techniques. The structural study revealed the formation of nanocomposite samples because of the co-existence of both alpha-Fe2O3 and NiFe2O4 phases. The NiFe2O4 phase in the nanocomposite increased with the increase of both Ni2+ and annealing temperatures. The morphological study reveals the presence of agglomerated irregular elliptical particles. The optical band gap of the samples remains unchanged with the increase of Ni2+ and annealing temperature. All the synthesized samples display effective exchange coupling and ferromagnetic features at room temperature. The magnetization of these systems increases with increasing NiFe2O4 phase and the progressive increase in magnetization is observed for the nanocomposites annealed at higher temperatures. The magnetization study at different temperatures revealed that there exists a critical measuring temperature for individual samples beyond which the magnetization starts reducing. The exchange bias in the nanocomposite samples depends on effective coupling between alpha-Fe2O3 and NiFe2O4 phases and the same is higher for the samples with x = 0.05.

Automated summary

The effect of thermal annealing on the structural, optical and magnetic properties of alpha-Fe2O3/Ni1+xFe2-xO4 nanocomposites was investigated. The results showed that annealing increased the NiFe2O4 phase and magnetization of the nanocomposites. The annealing temperature had no effect on the optical properties of the samples, but led to the formation of irregular elliptical particles. All synthesized samples displayed effective exchange coupling and ferromagnetic features at room temperature.