Magnetic study on Co3O4 nanoparticles

Ichiyanagi, Yuko; Kimishima, Y.; Yamada, Shigenori

doi:10.1016/j.jmmm.2003.12.377

Cited by 95 publications

(50 citation statements)

References 3 publications

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“…The inset in this figure shows the temperature dependence of the reciprocal magnetization 1/M, as measured in the FC process with the field of 0.01 T. As temperature is lowered from room temperature, a very sharp cusp at about 29 K is observed in the M ZFC curve with a dc magnetic field of 0.01 T, while a gradual increase of M FC appears, especially, below 50 K. Namely, an increasingly strong irreversibility is observed between M ZFC and M FC, with the onset of about 300 K. For M FC with the magnetic field of 1 T, it exhibits a behavior similar to that of M FC with the dc magnetic field of 0.01 T. As is well known, the blocking temperature T B (the temperature above which one particle has enough time, within the observation time, to reverse its moments to the applied field [21]) is the temperature correspondent to the maximum of M ZFC , or around 29 K. While bulk Cr is an antiferrromagnet with a Néel temperature T N of 311 K [22], Cr nanoparticles exhibit mainly antiferromagnetic (AFM) properties, in addition to a weak ferromagnetic (WFM) component [16]. According to Néel [23], WFM behaviors from very fine antiferromagnetic particles can be attributed to the uncompensated spins on the surfaces of the fine particles, which was also verified for a lot of AFM nanoparticles such as MnO [24], Co 3 O 4 [25] and Cr 2 O 3 [16] ones, etc. Moreover, ␤-Cr 2 N shows Pauli paramagnetic down to 1.8 K [26].…”

Section: Resultsmentioning

confidence: 89%

Structure and magnetic properties of Cr(N)–β-Cr2N nanoparticles prepared by arc-discharge

Feng

et al. 2006

Journal of Alloys and Compounds

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Section: Resultsmentioning

confidence: 89%

Structure and magnetic properties of Cr(N)–β-Cr2N nanoparticles prepared by arc-discharge

Feng

et al. 2006

Journal of Alloys and Compounds

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“…Co 3 O 4 is an antiferromagnetic material and in the bulk form, its Néel temperature has been reported to lie between 30 K and 40 K. 24 There have been some reports on hysteresis, time dependence of magnetization, exchange bias and finite size effects in bare, coated and dispersed Co 3 O 4 nanoparticles and various claims have been made in support of spin glass like and superparamagnetic behavior in these particles. [24][25][26][27][28][29][30][31][32][33] It will be, therefore, worthwhile to investigate their magnetic behavior carefully. In the present work, we present a de-tailed study on non-equilibrium features such as temperature, time and field dependence of magnetization, aging and memory effects.…”

Section: 19-21mentioning

confidence: 99%

Non-equilibrium effects in the magnetic behavior of Co3O4 nanoparticles

Bisht

Rajeev

2011

Solid State Communications

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We report detailed studies on non-equilibrium magnetic behavior of antiferromagnetic Co3O4 nanoparticles. Temperature and field dependence of magnetization, wait time dependence of magnetic relaxation (aging), memory effects and temperature dependence of specific heat have been investigated to understand the magnetic behavior of these particles. We find that the system shows some features characteristic of nanoparticle magnetism such as bifurcation of field cooled (FC) and zero field cooled (ZFC) susceptibilities and a slow relaxation of magnetization. However, strangely, the temperature at which the ZFC magnetization peaks coincides with the bifurcation temperature and does not shift on application of magnetic fields up to 1 kOe, unlike most other nanoparticle systems. Aging effects in these particles are negligible in both FC and ZFC protocol and memory effects are present only in FC protocol. We estimate the Néel temperature by using Fisher's relation as well as directly by measurement of specific heat, thus testing the validity of Fisher's relation for nanoparticles. We show that Co3O4 nanoparticles constitute a unique aniferromagnetic system which develops a magnetic moment in the paramagnetic state because of antiferromagnetic correlations and enters into a blocked state above the Néel temperature.

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“…C obalt oxide (Co 3 O 4 ) is a technologically important material with a variety of applications such as lithium ion batteries (Wang et al, 2002;Yuan et al, 2003), gas sensors (Li and Xu, 2005), magnetic materials (Ichiyanagi et al, 2004), and catalysts (Tang et al, 2006). Various techniques have been developed for the preparation of Co 3 O 4 powders, which include thermal decomposition method (Ardizzone et al, 1995;Liao and Liang, 2004;Wang and Zhu, 2005), sol-gel process (Cao et al, 2003), hydrothermal method (Cote et al, 2002;Meskin et al, 2003), and solvothermal (He et al, 2004;Nethravathi et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Kinetics of non‐isothermal decomposition of basic cobalt carbonate

Liu¹,

Peng²,

Zhang³

et al. 2010

Can J Chem Eng

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The kinetics of the thermal decomposition of basic cobalt carbonate was investigated under non-isothermal heating in air media using thermogravimetric analysis (TGA). TG-DTG curves showed that the decomposition proceeded through two well-fined steps in air. Weight loss of the thermal decomposition of basic cobalt carbonate was in good agreement with the theoretical weight loss. The isoconversional method has been applied to the data in order to evaluate a dependence of the effective activation energy on the extent of conversion, and the possible conversion functions have been estimated through the multiple linear regression method. The average apparent activation energies of the second steps (0.4 ≤˛≤0.9) were 96.607-144.537 kJ/mol. La cinétique de la décomposition thermique du carbonate basique de cobalt aétéétudiée dans des conditions de chauffage non-isotherme en milieu d'air utilisant l'analyse thermogravimétrique (TGA). Les courbes TG-DTG ont démontré que la décomposition s'est effectuée en deuxétapes bien définies en milieu d'air. La perte de poids de la décomposition thermique du carbonate basique de cobaltétait en concordance avec la perte de poids théorique. La méthode d'analyse isoconversionelle aété appliquée aux données afin d'évaluer une dépendance entre l'énergie effective d'activation et le degré de conversion, et les fonctions de conversion possibles ontété estimées par la méthode de régression linéaire multiple. Lesénergies d'activation moyennes apparentes issues des secondesétapes (0,4≤ ≤0,9)étaient de 96,607à 144,537 kJ/mol.

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Magnetic study on Co3O4 nanoparticles

Cited by 95 publications

References 3 publications

Structure and magnetic properties of Cr(N)–β-Cr2N nanoparticles prepared by arc-discharge

Structure and magnetic properties of Cr(N)–β-Cr2N nanoparticles prepared by arc-discharge

Non-equilibrium effects in the magnetic behavior of Co3O4 nanoparticles

Kinetics of non‐isothermal decomposition of basic cobalt carbonate

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