Structural and Magnetic Properties of Ultrafine CoFe2O4 Nanoparticles

Abstract

Nanosized Cobalt ferrite (CoFe2O4) particles are prepared through the sol-gel method using polyvinyl alcohol (PVA) as a chelating agent. The powder as prepared is annealed at three different temperatures (400 o C, 500 o C and 1000 o C) for one hour. The X-ray diffraction patterns confirm the spinel structure of the samples. The XRD patterns of the samples indicate broad peaks and the full width at half maximum decreased with increasing annealing temperature. Infrared (IR) spectra of the samples confirm the presence of metal -oxygen complexes within the spinel lattice. The average particle size obtained from TEM micrographs demonstrates ultrafine particles having spherical morphology. The particle size of the annealed samples is in between 4.5-6.8 nm. The saturation magnetization (Ms) and remnant magnetization (Mr) of the samples show dependence on particle size and crystallinity of the samples. The highest saturation magnetization (78.1 emu/g) is achieved for the sample annealed at 1000 0 C having average particle size of 6.8 nm. The high saturation magnetization of the samples suggests the present method is suitable for obtaining nanocrystalline magnetic ferrites which is desirable for practical applications.

Effect of apple cider vinegar agent on the microstructure, phase evolution, and magnetic properties of CoFe2O4 magnetic nanoparticles

“…In other words, the crystallite size is decreased, the degree of antisite defects at the surface is increased. Therefore, magnetic saturation decreases with a decrease in crystallite size due to the production of various canted spin structures at the surface of particles . On the other hand, as expected, the coercivity increases with an increase in the crystallite size and reaches a maximum value (~1038 Oe) for the specimen containing 5 mL ACV and then decreases.…”

“…So, the variation of H c with grain size is in good agreement with that reported by others. Furthermore, the calculated magnetic parameters related to the present work and the studies published by other researchers are compared in Table . As shown, the magnetic properties of CFO MNPs in the presence of ACV are better than that obtained in most of the previous works.…”

The effect of agarose content on the morphology, phase evolution, and magnetic properties of CoFe2O4 nanoparticles prepared by sol‐gel autocombustion method

“…36 It should be noted that magnetic properties of cobalt ferrite have direct dependent on the morphology, size, and particles purity which strongly are affected by primary parameters in producing route. Hence, several studies are carried out on the sol-gel and autocombustion synthesis of CoFe 2 O 4 using various agents such as citric acid, 11,13,[37][38][39][40][41] glycine, [41][42][43][44][45][46][47][48] urea, 13,41,49,50 hexamine, 51 glucose, 9 polyvinyl alcohol (PVA), 52,53 ethylene glycol (EG), 40,54 malic acid, 55 hexamethylenetetramine (HMT), 43 oxalyl dihydrazide (ODH), 49,56 thiourea, 50 and sago starch. 57 But, it is noted that with regard to biomedical applications of these NPs, the use of organic materials can be inappropriate.…”

Combustion assisted synthesis of hardystonite nanopowder

“…The presence of -COOH and -OH groups in the solution and their tendency to combine with Ca 2 þ and Zn 2 þ cause the formation of a homogenous solution and also prevent the recrystallization of sucrose and metal ions [22,23]. PVA is also another chelating agent that has been used in this study to better disperse metal ions [24].…”