Mössbauer and Structural Properties of La-Substituted Ni&lt;SUB&gt;0.4&lt;/SUB&gt;Cu&lt;SUB&gt;0.2&lt;/SUB&gt;Zn&lt;SUB&gt;0.4&lt;/SUB&gt;Fe&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;4&lt;/SUB&gt; Nanocrystalline Ferrite

Yang

et al. 2018

Materials

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Zinc ion-substituted cobalt ferrite powders Co1−xZnxFe2O4 (x = 0–0.7) were prepared by the sol-gel auto-combustion process. The structural properties and magnetic of the samples were investigated with X-ray diffraction (XRD), superconducting quantum interference device, and a Mössbauer spectrometer. The results of XRD showed that the powder of a single cubic phase of ferrites calcined when kept at 800 °C for 3 h. The lattice constant increases with increase in Zn concentration, but average crystallite size does not decrease constantly by increasing the zinc content, which is related to pH value. It was confirmed that the transition from ferrimagnetic to superparamagnetic behaviour depends on increasing zinc concentration by Mössbauer spectra at room temperature. Magnetization at room temperature increases for x ≤ 0.3, but decreases for increasing Zn2+ ions. The magnetization of Co0.7Zn0.3Fe2O4 reached maximum value (83.51 emu/g). The coercivity decreased with Zn2+ ions, which were doped on account of the decrease of the anisotropy constant.

Section: Resultsmentioning

confidence: 99%

Magnetic and Mössbauer Spectroscopy Studies of Zinc-Substituted Cobalt Ferrites Prepared by the Sol-Gel Method

Yang

et al. 2018

Materials

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“…When the nonmagnetic Al content was increased in CoAl x Fe 2− x O 4 , the samples changed into a superparamagnetic character. The behavior of the sample went from a completely magnetic state to a mixed state of magnetic and superparamagnetic order [11,12]. For samples with x = 1.5, Mössbauer spectra consisted only of a central doublet; this exhibits a superparamagnetic character.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2018

Nanomaterials

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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.

“…Nickel ferrite (NiFe 2 O 4 ) is a typical soft magnetic ferrite, making it one of the most important spinel ferrites [1]. It is widely used in electronic devices, due to its ability to remain permeable at high frequencies, high electrical resistivities, low eddy currents, and low dielectric losses, as well as its continuous chemical stability [2,3]. NiFe 2 O 4 is an inverse spinel ferrite, in which the Ni 2+ ions occupy octahedral (B) sites, and Fe 3+ ions are distributed in tetrahedral (A) and octahedral (B) sites [2].…”

Section: Introductionmentioning

confidence: 99%

“…It is widely used in electronic devices, due to its ability to remain permeable at high frequencies, high electrical resistivities, low eddy currents, and low dielectric losses, as well as its continuous chemical stability [2,3]. NiFe 2 O 4 is an inverse spinel ferrite, in which the Ni 2+ ions occupy octahedral (B) sites, and Fe 3+ ions are distributed in tetrahedral (A) and octahedral (B) sites [2]. The magnetic and electric properties of the spinel ferrites depend on the distribution of the cations among tetrahedral and octahedral sites.…”

Section: Introductionmentioning

confidence: 99%

Structural and Magnetic Studies of Cr3+ Substituted Nickel Ferrite Nanomaterials Prepared by Sol-Gel Auto-Combustion

et al. 2018

Crystals

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The present study envisages the preparation of chromium substituted Nickel ferrite NiCrxFe2−xO4 (x = 0~1.0) powders by a sol-gel auto-combustion method. X-ray diffraction analysis (XRD) showed that the specimens with x > 0.2 exhibited a single-phase spinel structure, and that more content of Cr within a specimen is favorable for the synthesis of pure Ni-Cr ferrites. The lattice parameter decreased with an increase in the Cr concentration. The sample without calcining exhibited a good crystallinity. Scanning Electron Microscopy (SEM) showed the formation of ferrite powders nano-particles, and that the substitution of Cr weakened the agglomeration between the particles. Mössbauer spectra of NiCrxFe2−xO4 showed two normal Zeeman-split sextets that displayed a ferrimagnetic behavior. Furthermore, the spectra indicated that iron was in the Fe3+ state, and the magnetic hyperfine field at the tetrahedral tended to decrease with an increase in the Cr substitution. The saturation magnetization decreased by the Cr3+ ions, and reached a minimum value (Ms = 4.46 emu/g). With an increase in the annealing temperature, the coercivity increased initially, which later decreased.