Magnetic and Structural Studies of CoFe 2 O 4 Nanoparticles Suspended in an Organic Liquid

Journal of Nanomaterials

et al. 2015

Zinc substituted magnesium ferrite nanomaterials Mg 1− Zn Fe 2 O 4 ( = 0, 0.1, 0.3, 0.5, 0.7) powders have been prepared by a solgel autocombustion method. The lattice parameter increases with increase in Zn concentration, but average crystallite size tends to decrease by increasing the zinc content. SEM results indicate the distribution of grains and morphology of the samples. Some particles are agglomerated due to the presence of magnetic interactions among particles. Room temperature Mössbauer spectra of Mg 1− Zn Fe 2 O 4 shows that the A Mössbauer absorption area decreases and the B Mössbauer absorption area increases with zinc concentration increasing. The change of the saturation magnetization can be explained with Néel's theory. It was confirmed that the transition from ferrimagnetic to superparamagnetic behaviour depends on increase in zinc concentration by Mössbauer spectra at room temperature. Saturation magnetization increases and coercivity decreases with Zn content increasing.

Section: Xrd Patterns Analysismentioning

confidence: 93%

“…2+ ions have a stronger preference for the tetrahedral sites [11,12], and Mg 2+ ions exist in both sites but have a preference for the octahedral site [3,4,[10][11][12]. The magnetic moment B is expressed as [4,5,11].…”

Section: Magnetic Property Of Particlesmentioning

confidence: 99%

Mössbauer Spectroscopy, Structural and Magnetic Studies of Zn²⁺ Substituted Magnesium Ferrite Nanomaterials Prepared by Sol‐Gel Method

Yang

Journal of Nanomaterials

et al. 2015

“…Hence, in this paper, it may be reasonable that rare earth ions (Gd 3+ ) are considered as nonmagnetic ones at room temperature. Since Co 2+ prefer to occupy the octahedral site (B) in CoFe 2 O 4 material of inverse spinel structure [1,2], Gd 3+ ions occupy only the B sites for their large ion radii [10,16]. That is, the cation distribution is (Fe) A [CoGd Fe 1− ] B O 4 .…”

Section: Magnetic Property Of Particlesmentioning

confidence: 99%

“…Cobalt ferrite is a hard magnetic material, and it has moderate saturation magnetization of about 80 emu/g, high coercivity of 5000 Oe, high Curie temperature of 793.15 K (520 ∘ C), high anisotropy constant of 2.65 × 10 6 ∼5.1 × 10 6 erg/cm 3 , and high magnetostrictive of −225 × 10 −6 [1,2]. Moreover, cobalt ferrite exhibits high electromagnetic performance, large magneto-optic effect, excellent chemical stability, and mechanical hardness [3,4].…”

Section: Introductionmentioning

confidence: 99%

The Structural and Magnetic Properties of Gadolinium Doped CoFe₂O₄ Nanoferrites

Journal of Nanomaterials

et al. 2015

Gadolinium substituted cobalt ferrite CoGd x Fe 2−x O 4 (x = 0, 0.04, 0.08) powders have been prepared by a sol-gel autocombustion method. XRD results indicate the production of a single cubic phase of ferrites. The lattice parameter increases and the average crystallite size decreases with the substitution of Gd 3+ ions. SEM shows that the ferrite powers are nanoparticles. Room temperature Mössbauer spectra of CoGd x Fe 22−x O 4 are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization decreases and the coercivity increases by the Gd 3+ ions.

“…The change trend of experimental and calculated saturation magnetization was similar for x ≤ 0.1, and there was deviation between experimental and calculated saturation magnetization, which can be attributed to the actual situation of ion distribution being more complicated than that obtained from the Mössbauer spectra. For the substituents ( x ≥ 0.5), there was a big difference between calculated saturation magnetization and experimental saturation magnetization, and the experimental value was smaller than the calculated value for saturation magnetization [18,19,20]. This can be explained by the three-sublattice model of Yafet-Kittel (YK) [16].…”

Section: Resultsmentioning

confidence: 99%

Effects of Al3+ Substitution on Structural and Magnetic Behavior of CoFe2O4 Ferrite Nanomaterials

et al. 2018

Nanomaterials

A sol-gel autocombustion method was used to synthesize Al3+ ion-substituted cobalt ferrite CoAlxFe2−xO4 (x = 0–1.5). According to X-ray diffraction analysis (XRD), cobalt ferrite was in a single cubic phase after being calcined at 1000 °C for 3 h. Moreover, the lattice constant decreased with increase in aluminum substituents. When the sample was analyzed by Scanning Electron Microscopy (SEM), we found that uniformly sized, well-crystallized grains were distributed in the sample. Furthermore, we confirmed that Al3+ ion-substituted cobalt ferrite underwent a transition from ferrimagnetic to superparamagnetic behavior; the superparamagnetic behavior was completely correlated with the increase in Al3+ ion concentration at room temperature. All these findings were observed in Mössbauer spectra. For the cobalt ferrite CoAlxFe2−xO4, the coercivity and saturation magnetization decrease with an increase in aluminum content. When the annealing temperature of CoAl0.1Fe1.9O4 was steadily increased, the coercivity and saturation magnetization initially increased and then decreased.