Evolution of Microstructure and Exchange Bias Characteristics of NiFe2O4/NiO nanocomposite

Abstract

Among the different well studied ferrite/metal oxide nanocomposites, NiFe 2 O 4 /NiO system has attracted considerable attention because of its excellent catalytic [15] and exchange bias (EB) characteristics [16-23]. The existence of EB coupling in this system demands its potentiality for designing permanent magnet [24-26] as well as other various applications like data storage (M-RAM), microelectronics (spin and tunneling valves), magnetic sensors (read/write heads), and medicine (drug delivery) [27, 28]. In this work, we review the effect of different conditions on the microstructure and exchange bias characteristics of NiFe 2 O 4 / NiO nanocomposite. Synthesis Methods There are several methods available in the literature for the synthesis of NiFe 2 O 4 /NiO nanocomposite in power and thin film form. Yanqing et al., [29] synthesized NiFe 2 O 4 /NiO by calcining the ball milled product of the initial ingredient of NiO and Fe 2 O 3. One can used chemical co-precipitation and post thermal decomposition [16, 17, 20-23] to obtain NiFe 2 O 4 / NiO nanocomposites. NiFe 2 O 4 /NiO nanocomposites have also been synthesized by the thermal treatment of NiFe-layered double hydroxides [19].NiO nanoparticles can be implanted into NiFe 2 O 4 nanowires chemically to prepare ordered NiO/NiFe 2 O 4 nanocomposites [14]. One can also adopt the Gen's levitation jet method to synthesize NiO/NiFe 2 O 4 composite [30, 31] NiFe 2 O 4 /NiO composite coating can be synthesized by heat treating the electroplated Ni-Fe alloy [32]. Thin films of NiFe 2 O 4 / NiO were also synthesized using high-pressure microplasmabased deposition [33]. Among the different method, chemical co-precipitation and post thermal decomposition method has been adopted in most of the studies. Evolution of Microstructure of NiFe 2 O 4 The crystal structure of NiFe 2 O 4 is not affected by varying the synthesis conditions. However, the microstructure of NiFe 2 O 4 is