Synthesis and anomalous magnetic properties of CoCr2O4 nanocrystallites with lattice distortion

Li, Shandong; Zhao, Guoxia; Hong, Bo; Huang, Zhigao; Lai, Heng; Gai, Rongquan; Du, Youwei

doi:10.1016/j.jmmm.2006.02.081

Cited by 26 publications

(5 citation statements)

References 23 publications

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“…The XRD pattern is fitted using cubic structure (Fd3m) with a ≈ 8.337 Å, which is in good agreement with the recent results [27,[33][34][35]. The difference plot at the bottom of figure 1 shows a satisfactory matching of the experimental curve with the computed one and the Rietveld analysis confirms the formation of singlephase of the sample and no other oxide phase can be detected from the diffraction plot [11,15,36]. The green bars at the bottom of XRD data indicate good matching of all the peak positions and correct indexing of the peaks, as depicted in figure 1.…”

Section: Structural Analysissupporting

confidence: 86%

“…The metal-oxygen bond for (A) site (OA) is directed towards the body diagonal of the cubic unit cell and metal-oxygen bond for [B] site (OB) is directed along the edges of the unit cell as shown in the model structure in inset of figure 1. Average crystallite size of the prepared sample is estimated from the XRD pattern using Scherrer's formula proposed by Williamson and Hall [34,36] as…”

Section: Structural Analysismentioning

confidence: 99%

“…Magnetic hysteresis loops (M-H) are measured at 2 K in between ± 80 kOe after cooling the sample from 300 K in ZFC and FC modes (shown in figure 5(a)) [36]. The non-saturation in the magnetization even in high magnetic field (± 80 kOe) may be related to large contribution of disordered spins at the surface of nanoparticles as well as ferrimagnetic nature of CoCr 2 O 4 [35].…”

Section: Magnetic Characterizationmentioning

confidence: 99%

See 2 more Smart Citations

Surface driven exchange bias in nanocrystalline CoCr₂O₄

Goswami¹,

Manna

Bedanta

et al. 2020

J. Phys. D: Appl. Phys.

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This article reports exchange bias (EB) in nanocrystalline cobalt chromite CoCr2O4, - a phenomenon manifested by loop shift followed by increase in coercivity after cooling the sample in static magnetic field. The average particle size of the nanocrystalline CoCr2O4 is 30 nm, confirmed from transmission electron microscopy images. Thermal variation of magnetization data M(T), in zero field cooling (ZFC) and field cooling (FC) modes depict long range order below the lock-in transition at TL≈16 K, spin-spiral transition at TS≈28 K and a collinear ferrimagnetic state at TC≈100 K. Magnetic hysteresis loops are recorded in ZFC and FC modes at different cooling fields (). In addition, hysteresis loops are recorded in FC mode for a wide temperature range. In both cases, a clear signature of conventional exchange bias effect is observed. Analysis of the training effect in magnetic hysteresis loop and temperature dependent ac susceptibility (χac) at different frequencies suggest that the surface spins of CoCr2O4 nanoparticles play an important role in controlling the magnetic properties, and enhance the EB effect in collaboration with competition between non-collinear spiral spin state and collinear long range ferrimagnetic order.

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Section: Structural Analysissupporting

confidence: 86%

Section: Structural Analysismentioning

confidence: 99%

Section: Magnetic Characterizationmentioning

confidence: 99%

See 1 more Smart Citation

Surface driven exchange bias in nanocrystalline CoCr₂O₄

Goswami¹,

Manna

Bedanta

et al. 2020

J. Phys. D: Appl. Phys.

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show abstract

“…AB 2 O 4 -type oxides with spinel structure. The EB effect has been reported in a few oxides, Ni 0.25 Co 0.25 Zn 0.5 Fe 2 O 4 [238], CoFe 2 O 4 [239] and CoCr 2 O 4 [240] having spinel structure. The EB effect was investigated on nanocrystalline Ni 0.25 Co 0.25 Zn 0.5 Fe 2 O 4 using a combination of in-field, low temperature Mössbauer spectroscopy and dc magnetization studies [238].…”

Section: Cobalt Oxidesmentioning

confidence: 92%

Exchange bias effect in alloys and compounds

Giri

Patra

Majumdar

2011

J. Phys.: Condens. Matter

321

225

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Abstract. The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, clusterglass, disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance.

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“…It is also used as ceramic material, heat resistant pigment [12,13], substrate for epitaxial growths [14,15], high density magnetic memory media, etc [16][17][18]. Cobalt chromite have been synthesized by sonochemical route [19,20], coprecipitation technique and heating Co 2+ and Cr +3 ions with styrene maleic acid copolymer in DMF medium [21].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Cobalt Chromite Nanoparticles by Thermolysis of Mixed Cr3+ and Co2+ Chelates of 2-Mercaptopyridin N-Oxide

Edrissi

Keshavarz

2012

Nano-Micro Lett.

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Pure greenish-blue cobalt chromite (CoCr2O4) nanoparticles with narrow particle range of 4.1±1.9 nm and surface area of 78.2 m 2 ·g −1 were synthesized through mixed chelates thermolysis of corresponding metals using 2-Mercaptopyridine N-oxide sodium salt as chelating agent. During the thermolysis procedure, high amount of gases were emitted that led to the formation of nanoparticles with high surface area. The product was characterized by TGA, DTG, XRD, TEM, SEM, LLS, BET and chemical analysis. Design of experiments was performed to fulfill the two levels L4 Taguchi design. It was found that the temperature and time of thermolysis process have significant effect on the particle size reduction. The Oxidation of trichloroethylene was carried out over CoCr2O4 nanocrystallite. Catalytic activity analysis revealed that the synthesis CoCr2O4 possesses high catalytic activity for this process.

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Synthesis and anomalous magnetic properties of CoCr2O4 nanocrystallites with lattice distortion

Cited by 26 publications

References 23 publications

Surface driven exchange bias in nanocrystalline CoCr₂O₄

Surface driven exchange bias in nanocrystalline CoCr₂O₄

Exchange bias effect in alloys and compounds

Synthesis of Cobalt Chromite Nanoparticles by Thermolysis of Mixed Cr3+ and Co2+ Chelates of 2-Mercaptopyridin N-Oxide

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Synthesis and anomalous magnetic properties of CoCr2O4 nanocrystallites with lattice distortion

Cited by 26 publications

References 23 publications

Surface driven exchange bias in nanocrystalline CoCr2O4

Surface driven exchange bias in nanocrystalline CoCr2O4

Exchange bias effect in alloys and compounds

Synthesis of Cobalt Chromite Nanoparticles by Thermolysis of Mixed Cr3+ and Co2+ Chelates of 2-Mercaptopyridin N-Oxide

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Product

Resources

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Surface driven exchange bias in nanocrystalline CoCr₂O₄

Surface driven exchange bias in nanocrystalline CoCr₂O₄