Magnetic properties of the mixed spinel CoFe2−xCrxO4

Mohan, Hari; Shaikh, I. A.; Kulkarni, R.G.

doi:10.1016/0921-4526(95)00620-6

Cited by 41 publications

(34 citation statements)

References 16 publications

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“…The magnetic properties of Al 3+ and Cr 3+ substituted cobalt ferrite have been reported separately [14,15], however, information about the structural and magnetic properties of co-substituted Al 3+ and Cr 3+ in cobalt ferrite, to our knowledge, is not yet reported in the literature. Hence, to investigate the properties, we synthesized CoAl x Cr x Fe 2-2x O 4 systems (x = 0.1 to 0.5 in steps of x = 0.1) by wet chemical co-precipitation technique.…”

Section: Introductionmentioning

confidence: 69%

Structural properties and magnetic interactions in Al3+ and Cr3+ co-substituted CoFe2O4 ferrite

More¹,

Kadam²,

Kadam³

et al. 2010

Open Chemistry

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A series of CoAl x Cr x Fe 2-2x O 4 systems (x = 0.1 to 0.5 in steps of x = 0.1) spinel ferrites have been synthesized successfully using wet chemical co-precipitation technique. The samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and magnetization measurements. The powder XRD patterns confirm the single phase spinel structure for the materials synthesized. X -ray diffraction measurements were performed to yield the lattice constant as function of the amount x corresponding to Al-Cr substitution. Lattice parameters, X-ray density, bulk density and particle size decrease whereas porosity increases with the increase in Al-Cr content, 'x'. Infrared studies show two absorption bands at about 400 cm -1 and 600 cm -1 for octahedral and tetrahedral sites, respectively. Saturation magnetization decreases with the increase in Al-Cr content x. AC magnetic susceptibility measurements were carried out as a function of temperature to measure the Curie temperature, which was found to decrease with Al-Cr content x. The decrease of Curie temperature has been explained by A-B interaction. Sp. z o.o. © Versita

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Section: Introductionmentioning

confidence: 69%

Structural properties and magnetic interactions in Al3+ and Cr3+ co-substituted CoFe2O4 ferrite

More¹,

Kadam²,

Kadam³

et al. 2010

Open Chemistry

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“…On the other hand, the concentration of Fe 3+ ions at the (B-) sites does not change despite the substitution by Cr 3+ ions till x = 0.7 due to the simultaneous inversion process in which the Co 2+ ions migrate to the (A-) sites [10]. This means that, the Cr 3+ ions occupy the (B-) sites.…”

Section: Results Of Crmentioning

confidence: 78%

“…Previous studies of magnetic properties and Mossbauer spectroscopy on mixed cobaltferri-chromites, CoCr x Fe 2−x O 4 , of coarse-grain composition indicated that canting of magnetic structure is observed when Co 2+ is present at the tetrahedral (A-) site [8,9]. While magnetization measurements on the same system could be explained by Neel's model as far as the series remained inverse spinel, they deviated significantly when they began to have normal spinel structure [10]. Recently, structural and magnetic properties of nanocrystalline CoCr x Fe 2−x O 4 (0 ≤ x ≤ 1.0) system prepared by the sol-gel autocombustion route have been studied by Tolesha et al [11].…”

Section: Introductionmentioning

confidence: 78%

“…Considering these facts, the positron trapping site in the undoped alloy can be conceived to be a vacancy cluster composed of the monovacancy created by the absence of a doubly ionized cation and four of its coordinated oxygen ions. Based on Xray diffraction, magnetization and Mossbauer results, Mohan et al [10] have shown that the CoFe 2 O 4 (x = 0.0) is a nearly complete inverse spinel and the ionic distribution in it is of the form (Fe 2+ ion with four oxygen neighbor ions will give rise to a neutral pentavacancy cluster in which positrons can be trapped and annihilated. The other possibility of the absence of a trivalent cation with four neighboring oxygen ions cannot be ruled out as it would have enhanced positron trapping due to surplus negative charge, and hence, it is necessary to point out whether the said vacancy cluster is centered at the (A-) site or at the (B-) site.…”

Section: Results Of Crmentioning

confidence: 99%

See 1 more Smart Citation

Crystal Defects and Cation Redistribution Study on Nanocrystalline Cobalt-Ferri-Chromites by Positron Annihilation Spectroscopy

Modi

Vasoya

Lakhani

et al. 2013

International Journal of Spectroscopy

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Positron lifetime and Doppler broadening measurements were carried out on nanocrystalline (grain size ∼60-65 nm) samples of the Cr 3+ -substituted cobalt ferrite system with general chemical formula CoCr x Fe 2−x O 4 ( = 0.0−2.0) synthesized by the coprecipitation technique. The results indicated selective trapping of positrons in large vacancy clusters initially at the tetrahedral (A-) sites and then with Cr 3+ -substitution up to concentration ( ) = 0.7, at the octahedral (B-) sites. The results are consistent with the cation distribution determined from X-ray diffraction line intensity calculations, which indicated partial inversion of the inverse spinel ferrite, subsequent stabilization over a range of substitution ( = 0.7 to 1.7), and finally the full inversion to the normal spinel chromite (CoCr 2 O 4 , = 2.0). In the intermediate range of substitution, lattice contraction prevented a fraction of Co 2+ ions released from the (B-) sites from entering the tetrahedral sites, and these vacancies at the (A-) sites trapped positrons. Although the samples were composed of nanocrystalline grains, only an insignificant fraction of positrons were diffused and annihilated at the grain surfaces, since the grain sizes and the thermal diffusion length of positrons nearly overlapped.

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“…So far, many investigations have been carried out on the effect of zinc and/or copper substitutions in different ferrite systems on the properties of the samples. Compositions like NiCr x Fe 2−x O 4 [11], CoCr x Fe 2−x O 4 [12,13], CoFe 2−x Cr x O 4 [14], Cr x Fe 3−x O 4 [15], FeCr x Fe 3−x O 4 [16], NiFe 2−x Cr x O 4 [17], NiFe 2−x Cr x O 4 [18].…”

Section: Introductionmentioning

confidence: 99%

Structural and Magnetic Properties of NiCr x Fe2−x O4 Nanoparticles Synthesized via Microwave Method

Baykal

Elmal

Sertkol

et al. 2015

J Supercond Nov Magn

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The nanocrystalline NiCr x Fe 3−x O 4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) have been synthesized by microwaveassisted combustion method, and the effect of Cr 3+ substitution on the structural and magnetic properties of NiFe 2 O 4 was studied. Phase formation was identified by X-ray powder diffraction (XRD), which confirmed the formation of a cubic spinel structure for all the compositions. The lattice "a" of all samples decreases with the increase in Cr contents in the compositions. The elemental analysis by scanning electron microscopy-energy dispersive X-ray was in close agreement with the expected composition from the stoichiometry of the starting composition used for the synthesis. NiFe 2 O 4 and NiCr 0.2 Fe 1.8 O 4 nanoparticles (NPs) show features of superparamagnetin NPs, namely reduced and unsaturated magnetization together with the absence of coercivity.

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Magnetic properties of the mixed spinel CoFe2−xCrxO4

Cited by 41 publications

References 16 publications

Structural properties and magnetic interactions in Al3+ and Cr3+ co-substituted CoFe2O4 ferrite

Structural properties and magnetic interactions in Al3+ and Cr3+ co-substituted CoFe2O4 ferrite

Crystal Defects and Cation Redistribution Study on Nanocrystalline Cobalt-Ferri-Chromites by Positron Annihilation Spectroscopy

Structural and Magnetic Properties of NiCr x Fe2−x O4 Nanoparticles Synthesized via Microwave Method

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