Magnetic properties of nanoparticles produced by a new chemical method

Duque, Juan G.; Souza, E.A.; Meneses, C.T.; Kubota, Lauro T.

doi:10.1016/j.physb.2007.04.030

Cited by 51 publications

(30 citation statements)

References 24 publications

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“…Local spin arrangements [38] for the Nb-doped NiZn ferrites were estimated (i.e., the magnetic moments in terms of Bohr's magnetons, n B ) as given by…”

Section: Magnetic Studiesmentioning

confidence: 99%

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Experimental characterization of nanocrystalline niobium-doped nickel–zinc ferrites: occurrence of superparamagnetism

Lakshmi¹,

Sridhar

Govindraj

et al. 2016

J Mater Sci

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Structural, morphological, magnetic, and dielectric investigations are carried out in Nb-doped (viz., for x equal to 0.0-0.4 by wt%) nanocrystalline Ni-Zn ferrites synthesized by hydrothermal method. XRD, IR studies infer the growth of nano structures and Fe 2 O 3 phase. Nb ions segregate at grain boundaries. Crystallite size (D) varies from 62 to 18 nm with x. FTIR absorption exhibits split at higher x. Saturation magnetization witnesses an overall decrease with x. Trends of M s (x) are explained by nature of dopant, preferential replacement, surface canting (Y-K angles) and lattice contraction. Variations of coercive field (H c ) and D infer singledomain to multi-domain morphological transformation. Occurrence of superparamagnetism (SPM) is predicted for zeroed values of H c and for a critical concentration x crit equal to 0.321. Enhanced Nb 5? -Fe 2? binding with dopant (x up to 0.2) results for decrease in dielectric constant e 0 r , loss factor tand and increase in resistivity q. Lowered ac conductivity is attributed to blockade of path by Nb 5? ions in the vicinity of B-sites. Relatively higher q (*10 8 X cm) and lower loss (tand *10 -2 -10 -3 ) evinced for 10 kHz. Enhanced core loss is realized with x manifested as lowered H c and tand to usher their utility in high-frequency applications.

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“…Local spin arrangements [38] for the Nb-doped NiZn ferrites were estimated (i.e., the magnetic moments in terms of Bohr's magnetons, n B ) as given by…”

Section: Magnetic Studiesmentioning

confidence: 99%

“…Thus, the observed overall decreasing trend of M s is found to agree with the logical predictions [56,57] of Neel's 2-sublattice model. However, to explain the overall lowered trend of M s , Y-K angles are also estimated [38][39][40] (from Eqs. 6 and 7 of Sect.…”

Section: Magnetic Studiesmentioning

confidence: 99%

Experimental characterization of nanocrystalline niobium-doped nickel–zinc ferrites: occurrence of superparamagnetism

Lakshmi¹,

Sridhar

Govindraj

et al. 2016

J Mater Sci

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“…According to Néel's two sublattice model of ferrimagnetism [11,12], saturation magnetization is described by M s = M B − M A , where M B and M A are the octahedral and tetrahedral sublattice magnetizations, respectively. Furthermore, the electron spins within 'A' and 'B' sites are parallel, while these are antiparallel to each other at the A and B sites [4].…”

Section: As a Function Of Dopants Zr And Ni Contents Xmentioning

confidence: 99%

Electrical and Magnetic Properties of Zr4+ and Ni2+ Ions Substituted Mn–Cu Spinel Ferrites

Faraz

Ahmad

2011

J Supercond Nov Magn

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The Mn-Cu nanoferrites of composition Mn 0.5 Cu 0.5 Fe 2 − 2x Ni x Zr x O 4 (0.00 ≤ x ≤ 0.80) were synthesized by incorporating dopant Zr 4+ and Ni 2+ cations via a chemical coprecipitation technique. The single phase of the prepared spinel nanoferrites with particle sizes 15-31 nm was confirmed by XRD. Both electrical and magnetic properties are found to depend on the x contents and explained by considering the Zr 4+ and Ni 2+ cations distribution, displacement of the Fe 3+ ions by dopants, changes in magnetic moment at tetrahedral A site and octahedral B site, Fe 3+ (A)-O 2 -Fe 3+ [B] linkages and extent of the primary superexchange interactions (A)-O-[B] of the Fe 3+ ions on the A and B-sites. DC resistivity, saturation magnetization (M s ), remanence (M r ) and Bohr magneton (n B ) are observed to increase up to x ≤ 0.40, while these parameters fall at relatively higher value of x ≥ 0.60.

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“…As a kind of important spinel ferrite, NiFe 2 O 4 has attracted much interest because of its fascinating magnetic and electromagnetic properties 1 . NiFe 2 O 4 powders have been studied to use in many fields, such as ferrofluids 2,3 , catalysts 4 , gas sensors [5][6][7][8] , biomedicine 9 and so on [10][11][12] . NiFe 2 O 4 is a cubic ferromagnetic oxide with a typical inverse spinel structure where Ni 2+ ions occupy octahedric B-sites and Fe 3+ ions equally distributed between tetrahedric A-sites and octahedric B-sites 13 .…”

Section: Introductionmentioning

confidence: 99%

“…NiFe 2 O 4 is a cubic ferromagnetic oxide with a typical inverse spinel structure where Ni 2+ ions occupy octahedric B-sites and Fe 3+ ions equally distributed between tetrahedric A-sites and octahedric B-sites 13 . Nanoscale NiFe 2 O 4 ferrites have been successfully synthesized by various methods including sol-gel 11,[14][15][16] , solid-state reaction 6,[17][18] , co-precipitation 7,12,19,20 , mechanochemical 21 , rheological phase reaction method 22 , pulsed wire discharge 23 , arc plasma assisted gas phase synthesis method 24 , combustion 25 , surfactant-assisted refluxing method 26 , micromulsion 27 , electrospinning 28 , thermolysis of mixed metal-oleate complexes 29 , sonochemical 30 and hydrothermal [31][32][33][34][35] . In this paper, we report a novel one-step, simple method to directly synthesize uniform, mass-production nanostructured NiFe 2 O 4 by the composite-hydroxide-salt-mediated (CHSM) method.…”

Section: Introductionmentioning

confidence: 99%

Facile synthesis of inverse spinel NiFe2O4 nanocrystals and their superparamagnetic properties

2012

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Spinel NiFe 2 O 4 nanocrystals have been obtained by means of a novel composite-hydroxide-salt-mediated approach, which is based on a reaction between metallic salt and metallic oxide in the solution of composite-hydroxide-salt eutectic at ~225 °C and normal atmosphere without any organic dispersant or capping agent. The obtained products are characterized by an X-ray diffraction (XRD), a transmission electron microscopy (TEM) and an alternating gradient magnetometer (AGM). The formation process of NiFe 2 O 4 nanosheet is proposed to begin with a ''dissolution-recrystallization'' which is followed by an ''Ostwald ripening'' mechanism. The NiFe 2 O 4 nano-octahedrons can be obtained through adjusting the reaction water content in the hydroxide melts at constant temperature. At 300 K, magnetic hysteresis loops at an applied field of 15 kOe show zero coercivity, indicating the superparamagnetic behavior of the as-prepared NiFe 2 O 4 nanocrystals.

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Magnetic properties of nanoparticles produced by a new chemical method

Cited by 51 publications

References 24 publications

Experimental characterization of nanocrystalline niobium-doped nickel–zinc ferrites: occurrence of superparamagnetism

Experimental characterization of nanocrystalline niobium-doped nickel–zinc ferrites: occurrence of superparamagnetism

Electrical and Magnetic Properties of Zr4+ and Ni2+ Ions Substituted Mn–Cu Spinel Ferrites

Facile synthesis of inverse spinel NiFe2O4 nanocrystals and their superparamagnetic properties

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