M�ssbauer Studies of Superexchange Interaction in Tetragonal CuFe2O4

Oak, Hang Nam; Baek, Kyung Seon; Kim, Sam Jin

doi:10.1002/(sici)1521-3951(199807)208:1<249::aid-pssb249>3.0.co;2-b

Cited by 25 publications

(16 citation statements)

References 7 publications

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“…The NiFe 2 O 4 is completely inverse spine, because Ni 2+ has a strong preference for the electrical conductivity octahedral site (B-site) [1]. Cadmium is the non magnetic divalent ions which occupy essentially tetrahedral A-site [2] when substituted in ferrites.…”

Section: Introductionmentioning

confidence: 92%

Electrical Properties of Cadmium Substitution in Nickel Ferrites

Ande¹,

Somaiah²,

Ravinder³

et al. 2012

WJCMP

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Electrical transport properties such as conductivity (σ) and thermo electric power (S) of Cadmium substituted Nickel Ferrites, forming chemical formula Ni 1-x Cd x Fe 2 O 4 , where x = 0.0, 0.2, 0.4 have been investigated from room temperature to well beyond the Curie temperature. Plots of log (σT) versus 10 3 /T are linear and show a transition near the Curie temperature. The transition temperature is found to decrease with increase of Cd content. On the basis of Seebeck coefficient (S), the ferrites under investigation have been classified as n-type and p-type semiconductors. The values of charge carrier concentration and mobility have been computed from experimental values of Seebeck coefficient and electrical conductivity. The activation energy in the ferrimagnetic region is in general less than that in the paramagnetic region. An attempt is made to explain the conduction mechanism in these ferrites.

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Section: Introductionmentioning

confidence: 92%

Electrical Properties of Cadmium Substitution in Nickel Ferrites

Ande¹,

Somaiah²,

Ravinder³

et al. 2012

WJCMP

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“…Under controlled conditions, the ferrites crystallize in the spinel structure AB 2 . Two sets of data, for example hyperfine fields and magnetic moments are required to determine the super-exchange integrals [3,4]. Provided the hyperfine fields at 57 Fe nuclei at the A and B sites are clearly resolved, Mössbauer measurements allow accurate determination of these fields, and hence provide two series of data which, without the use of external fields, can be used to infer reliable information on super-exchange interactions.…”

Section: Introductionmentioning

confidence: 94%

Mössbauer Studies on (Zn, Cd, Cu)0.5Ni0.5Fe2O4 Oxides

et al. 2004

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The temperature dependence of the magnetic hyperfine fields on 57 Fe nuclei at the tetrahedral (A) and octahedral (B) interstitial sites in (Zn, Cd, Cu) 0.5 Ni 0.5 Fe 2 O 4 oxides have been investigated in Mössbauer measurements at sample temperatures ranging from 79 K to 850 K. The samples were prepared by solid-state reaction, and their phase determined from XRD measurements, which also provided information on their X-ray densities, grain sizes and lattice constants. The magnetic transition temperatures between ordered and paramagnetic states were obtained from zero-velocity measurements. The Cu 0.5 Ni 0.5 Fe 2 O 4 sample is found to be antiferromagnetic with Néel temperature of 823 K, and its super-exchange interactions, J AB , J AA and J BB were determined to be j24.14 k B , j13.10 k B and +11.68 k B , respectively. The (Zn, Cd) 0.5 Ni 0.5 Fe 2 O 4 are ferrimagnetic with Curie points of 543 and 548 K, respectively, and corresponding average exchange integrals J o = 186 k B and 188 k B .

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“…The exchange integrals can be determined from the two sets of data of hyperfine fields at A and B sites [1]. These fields can be accurately determined from Mössbauer measurements if they are well resolved and hence infer reliable information on superexchange interactions.…”

Section: The Intrasublattice Interactions (A-o-a) and (B-o-b)mentioning

confidence: 99%

“…The measurements of hyperfine fields in ferrite materials have been routinely obtained in previous works [1][2][3][4][5][6][7][8][9][10]. However the temperature analysis of the hyperfine fields as a function of temperature (B hf (T)) has not been exhaustive [1][2][3][4][5][6][7][8].…”

Section: The Intrasublattice Interactions (A-o-a) and (B-o-b)mentioning

confidence: 99%

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Temperature dependence of the hyperfine fields in NiFe2O4 and CuFe2O4 oxides

Msomi

Moyo

2007

Hyperfine Interact

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We report the temperature dependence of the magnetic properties of (Ni, Cu)Fe 2 O 4 spinel oxides. Mössbauer spectra for NiFe 2 O 4 at various temperatures (79 ≤ T ≤ 900 K) are well fitted by two sextets associated with 57 Fe nuclei at tetrahedral (A) and octahedral (B) sites. The Curie point T C was deduced by zero velocity Mössbauer technique to be 873 ± 3 K. The hyperfine fields are observed to vary with temperature according to the equationwhere n = 1 (based on the Landau-Ginzburg theory) and n = 2 (based on the Stoner theory). A systematic decrease of the Mössbauer spectrum shift with increasing temperature is observed. KeywordsFerrites · Mössbauer spectroscopy · Hyperfine fields Ferrites are a group of oxides with the spinel crystal structure AB 2 O 4 , where A and B cations are contained in the tetrahedral (A) and octahedral (B) sites. The magnetic order depends on different superexchange interactions mediated by intervening oxygen ions. The superexchange interactions are characterized by the exchange integrals J AB (A-O-B), J AA (A-O-A) and J BB (B-O-B). Ferrimagnetic ordering takes place when the intersublattice interaction (A-O-B) is stronger than

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M�ssbauer Studies of Superexchange Interaction in Tetragonal CuFe2O4

Cited by 25 publications

References 7 publications

Electrical Properties of Cadmium Substitution in Nickel Ferrites

Electrical Properties of Cadmium Substitution in Nickel Ferrites

Mössbauer Studies on (Zn, Cd, Cu)0.5Ni0.5Fe2O4 Oxides

Temperature dependence of the hyperfine fields in NiFe2O4 and CuFe2O4 oxides

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