Enhancement of room-temperature magnetoresistance in polyvinyl acetate encapsulated Fe3O4 nanoparticles

Magnetoresistance (MR) properties of magnetic materials

“…For example, in the case of SnFe 2 O 4 , this cubic spinel structure can be clearly identified through X-ray diffraction (XRD) analysis, 11 MCr 2 S 4 (M = Fe & Co), 121 and Fe 3 O 4. 122 For example, in the study conducted by Dey et al , 121 using the compounds FeCr 2 S 4 and CoCr 2 S 4 with spinel structures synthesized through the solid-state reaction method, the XRD results in Fig. 5B , refined using Rietveld refinement, showed that the materials have a cubic FCC spinel structure (No.…”

“…5C ) with a concentration of 0.4 M was approximately 34 nm, whereas for a concentration of 0.05, the crystal size was approximately 23 nm. 122 Higher lattice strain occurs in materials with smaller crystal sizes, resulting from lower precursor concentrations. Small crystal sizes can lead to larger grain boundaries and higher defect concentrations.…”

“…These data were then fitted by calculating the full-width at half maximum (FWHM) of the four samples, which were approximately 22, 20, 22, and 18 nm for concentrations of 0.4, 0.2, 0.1, and 0.05 M, respectively. 122 A higher full-width half maximum (FWHM) in the particle size distribution indicates a broader range of particle sizes. The crystallite size, morphology, and particle size of nanoparticles depend on several factors, including reaction temperature, solvent, surfactant, and precursor concentration.…”

“…[C] X-ray diffraction data of Fe 3 O 4 nanoparticles prepared using different concentrations of precursor). Reprinted with permission from the Elsevier 122. [D] FESEM images showing the surface morphology of Fe 3 O 4 nanoparticles prepared from different precursor concentrations).…”

Annealing effects on the magnetic and magnetotransport properties of iron oxide nanoparticles self-assemblies

“…These effects can be exacerbated by the thermal annealing, which is usually performed in vacuum or inert atmosphere. Therefore, additional Fe 3 O 4 functionalization with organic molecules as acetic acid, amine, polyvinyl acetate [24,26,[38][39][40], or inorganic coatings as SiO 2 or ZrO 2 [29,[41][42][43] were studied in order to enhance the room-temperature magnetoresistance, by improving the NPs arrays and/or protecting the nanoparticle surface from oxidation. However, this step complicates the fabrication process and it is found that the enhancement of TMR is still far away from the predicted value.…”