Structural and magnetic properties of CoFe 2−x Mo x O 4 nanocrystalline ferrites

Mohamed, Mohamed Bakr; Wahba, Adel Maher; Yehia, M.

doi:10.1016/j.mseb.2014.09.010

Cited by 33 publications

(18 citation statements)

References 25 publications

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“…There has been only a very little work reported in the literature on the properties of non-magnetic Mo incorporated CFO. [32][33][34] Furthermore, while there exists very few efforts, fundamental understanding of the structure-composition-property relation in Mo-incorporated CFO is missing at this time. Additionally, although still some unanswered, fundamental scientific questions exists, recently observed and/or predicted ferroelectric/multiferroic character of Mo incorporated CFO is promising for future applications in magneto-electronics.…”

Section: Introductionmentioning

confidence: 99%

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

et al. 2017

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Melendez, A.; Manadhar, S.; Singamaneni, S. R.; Reddy, Kongara M.; Gandha, Kinjal H.; Niebedim, I. C.; and Ramana, C. V., "Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite" (2017). Ames Laboratory Accepted Manuscripts. 61. AbstractWe report on the effect of molybdenum (Mo) incorporation on the crystal structure, surface morphology, Mo chemical valence state, and magnetic properties of cobalt ferrite (CoFe2O4, referred to CFO). Molybdenum incorporated cobalt ferrite (CoFe2-xMoxO4, referred to CFMO) ceramics were prepared by the conventional solid-state reaction method by varying the Mo concentration in the range of x = 0.0-0.3. X-ray diffraction studies indicate that the CFMO materials crystallize in inverse spinel cubic phase. Molybdenum incorporation induced lattice parameter increase from 8.322 to 8.343 Å coupled with a significant increase in density from 5.4 to 5.7 g/cm3 was evident in structural analyses. Scanning electron microscopy imaging analyses indicate that the Mo incorporation induces agglomeration of particles leading to larger particle size with increasing x(Mo) values. Detailed X-ray photoelectron spectroscopic (XPS) analyses indicate the increasing Mo content with increasing x from 0.0 to 0.3. XPS confirms that the chemistry of Mo is complex in these CFMO compounds; Mo ions exist in the lower oxidation state (Mo4+) for higher x while in a mixed chemical valence state (Mo4+, Mo5+, Mo6+) for lower x values. From the temperature-dependent magnetization, the samples show ferrimagnetic behavior including the pristine CFO. From the isothermal magnetization measurements, we find almost 2-fold decrease in coercive field (Hc) from 2143 to 1145 Oe with the increase in Mo doping up to 30%. This doping-dependent Hc is consistently observed at all the temperatures measured (4, 100, 200, and 300 K). Furthermore, the saturation magnetization estimated at 4 K and at 1.5 T (from M-H loops) goes through a peak at 92 emu/g (at 15% Mo doping) from 81 emu/g (pristine CFO), and starts decreasing to 79 emu/g (at 30% Mo doping). The results demonstrate that the crystal structure, microstructure, and magnetic properties can be tuned by controlling the Mo-content in the CFMO materials. ABSTRACTWe report on the effect of molybdenum (Mo) incorporation on the crystal structure, surface morphology, Mo chemical valence state and magnetic properties of cobalt ferrite (CoFe2O4, referred to CFO). Molybdenum incorporated cobalt ferrite (CoFe2-xMoxO4, referred to CFMO) ceramics were prepared by the conventional solid-state reaction method by varying the Mo concentration in the range of x=0.0-0.3. X-ray diffraction studies indicate that the CFMO materials crystallize in inverse spinel cubic phase. Molybdenum incorporation induced lattice parameter increase from 8.322 to 8.343 Å coupled with a significant increase in density from 5.4 to 5.7 g/cm 3 was evident in structural analyses. Scanning electron microscopy imaging analysis indicate that the Mo incorporation induces agglomeration of pa...

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Section: Introductionmentioning

confidence: 99%

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

et al. 2017

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“…By using different methods of preparation, different size, shapes, and size distribution are obtained [4]. Several chemical methods have been developed to produce nanocrystalline ferrites, e.g., sol-gel [5,6], citrate precursor [7], co-precipitation [8], and microwave-assisted hydrothermal [9]. Among different dopants, nickel-zinc ferrites happen to be the most researched materials due to their remarkable magnetic properties such as large permeability at high frequency, remarkably high electrical resistivity, and low power loss [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Ultrasmall Nanocrystalline Zn-substituted Ni-Sm-Ga Ferrites

Yehia

Ismail

Mohamed

2015

J Supercond Nov Magn

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Ultrasmall nanocrystalline NiSm 0.01 Fe 1.99 O 4 and Ni 1−x Zn x Sm 0.01 Ga 0.5 Fe 1.49 O 4 (x = 0.0, 0.3, 0.5) ferrites were synthesized by sol-gel method. The effect of Ga and Zn substitution on the particle size and structural and magnetic properties was investigated using X-ray diffraction patterns (XRD), transmission electron microscope (TEM), Mössbauer effect spectroscopy (ME), and vibrating sample magnetometer (VSM) techniques. XRD measurements suggest the formation of single-phase spinel ferrites with ultrasmall particles size ranging from 4 to 8 nm. Mössbauer effect measurements show a clear signature of superparamagnetism in the studied samples, where the reduced particle size causes the broadening of the Mössbauer spectra and the presence of a pronounced central doublet in all the measured samples. VSM measurements show a strong reduction of saturation magnetization due to size effects.

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“…Where Manganese ferrite has been used extensively in the microwave and magnetic recording applications [3]. And cobalt ferrite CoFe 2 O 4 has a wide range of applications in high-frequency devices and memory cores because cobalt ferrite has a unique property over the rest of ferrites which is high magneto-crystalline anisotropy [4]. CoFe 2 O 4 also has high Curie temperature T c , reasonable saturation magnetization, and high coercivity [4].…”

Section: Introductionmentioning

confidence: 99%

“…And cobalt ferrite CoFe 2 O 4 has a wide range of applications in high-frequency devices and memory cores because cobalt ferrite has a unique property over the rest of ferrites which is high magneto-crystalline anisotropy [4]. CoFe 2 O 4 also has high Curie temperature T c , reasonable saturation magnetization, and high coercivity [4]. Both MnFe 2 O 4 and CoFe 2 O 4 are recognized as mixed inverse spinel but the degree of inversion depends basically upon the preparation conditions including sintering temperature [5] [6].…”

Section: Introductionmentioning

confidence: 99%

Controlling the Structural and Physical Properties of as-Synthesized Co-Mn Ferrite Nanoparticles by Adding Cr Ions

2020

Egyptian Journal of Solids

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In this paper, mixed spinel Co-Mn-Cr ferrite with varying chromium content have been investigated to deduce the relation between the structure and some physical properties; electric, optical and magnetic. Nano-crystalline Co 0.7 Mn 0.3 Cr x Fe 2-x O 4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1) were synthesized via co-precipitation route. The obtained particle size from transmission electron microscope (TEM) micrographs is close to the crystallite size calculated from X-ray diffraction (XRD) by Sherrer's formula, and the particle size distribution is regular. The infrared spectra represent two strong absorption bands around 600-400 cm −1 , which confirm the presence of M-O stretching bond. The mechanical properties enhanced by adding Cr 3+ ions. The optical band-gap calculated from UVvisible spectroscopy is quite affected by adding Cr 3+ ions because of particle size reduction. The saturation magnetization (M s) and the coercivity (H c) decrease with Cr 3+ ions substitution. The variations of the electrical conductivity and drift mobility with temperature were also investigated. The conduction mechanism changed from electron hopping to polaron hopping by raising the temperature. Superparamagnetic Co 0.7 Mn 0.3 Cr x Fe 2-x O 4 (x ≥ 0.6) nanocrystals can be used in biomedical applications and low power-loss applications. The sample Co 0.7 Mn 0.3 Cr 0.2 Fe 1.8 O 4 has high squareness ratio (M r /M s) and, it may be suitable for memory applications.

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Structural and magnetic properties of CoFe 2−x Mo x O 4 nanocrystalline ferrites

Cited by 33 publications

References 25 publications

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

Effect of Molybdenum Incorporation on the Structure and Magnetic Properties of Cobalt Ferrite

Synthesis and Characterization of Ultrasmall Nanocrystalline Zn-substituted Ni-Sm-Ga Ferrites

Controlling the Structural and Physical Properties of as-Synthesized Co-Mn Ferrite Nanoparticles by Adding Cr Ions

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