Mössbauer studies on MnGaxFe2−xO4

Mahmoud, M.H.; Hamdeh, Hussein H.; Ho, J.C.; Abdalla, Atef M.; Abdel-Mageed, A.I.

doi:10.1016/s0038-1098(01)00398-2

Cited by 10 publications

(4 citation statements)

References 5 publications

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“…9,10 In the present study, a family of Gasubstituted cobalt ferrite CoGa x Fe 2−x O 4 samples has been investigated. Ga 3+ is known to prefer the tetrahedral sites, 11,12 therefore the results were expected to be different from those of Mn-and Cr-substituted cobalt ferrites.…”

Section: Introductionmentioning

confidence: 94%

Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite

Song

Lee

et al. 2007

Journal of Applied Physics

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Magnetic and magnetoelasticproperties of a series of Ga-substituted cobaltferrites,CoGaxFe2−xO4 (x=0.0-0.8), have been investigated. The Curie temperatureTCand hysteresis properties were found to vary with gallium content (x), which indicates that exchange and anisotropy energies changed as a result of substitution of Ga for Fe. The maximum magnitude of magnetostriction decreased monotonically with increasing gallium content over the range x=0.0-0.8. The rate of change of magnetostriction with applied magnetic field (dλ/dH) showed a maximum value of 3.2×10−9A−1m for x=0.2. This is the highest value among recently reported cobaltferrite based materials. It was found that the dependence of magnetic and magnetoelasticproperties on the amount of substituent (x) was different for Mn, Cr, and Ga. This is considered to be due to the differences in cation site occupancy preferences of the elements within the spinel crystal structure: Mn3+ and Cr3+ prefer the octahedral (B) sites, whereas Ga3+ prefers the tetrahedral (A) sites. KeywordsAmes Laboratory, CNDE, Cobalt, Ferrites, Magnetostriction, Magnetic anisotropy, Curie point Disciplines Materials Science and Engineering CommentsThe following appeared in Journal of Applied Physics 101 ( Magnetic and magnetoelastic properties of a series of Ga-substituted cobalt ferrites, CoGa x Fe 2−x O 4 ͑x = 0.0-0.8͒, have been investigated. The Curie temperature T C and hysteresis properties were found to vary with gallium content ͑x͒, which indicates that exchange and anisotropy energies changed as a result of substitution of Ga for Fe. The maximum magnitude of magnetostriction decreased monotonically with increasing gallium content over the range x = 0.0-0.8. The rate of change of magnetostriction with applied magnetic field ͑d / dH͒ showed a maximum value of 3.2ϫ 10 −9 A −1 m for x = 0.2. This is the highest value among recently reported cobalt ferrite based materials. It was found that the dependence of magnetic and magnetoelastic properties on the amount of substituent ͑x͒ was different for Mn, Cr, and Ga. This is considered to be due to the differences in cation site occupancy preferences of the elements within the spinel crystal structure: Mn 3+ and Cr 3+ prefer the octahedral ͑B͒ sites, whereas Ga 3+ prefers the tetrahedral ͑A͒ sites.

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Section: Introductionmentioning

confidence: 94%

Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite

Song

Lee

et al. 2007

Journal of Applied Physics

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“…The effects of this substitution were expected to be different for Mn and Cr substitution. [5][6][7] …”

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confidence: 99%

Investigation of Ga substitution in cobalt ferrite (CoGaxFe2−xO4) using Mossbauer spectroscopy

Krieble¹,

Devlin²,

Lee³

et al. 2008

Journal of Applied Physics

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Ga-substituted cobalt ferrite oxides show promise as high magnetostriction, high sensitivity magnetoelastic materials for sensor and actuator applications, but their atomic-level behavior is not yet well understood. In this study, the magnetic environments of the Fe atoms in Ga-substituted cobalt ferrite have been investigated using Mossbauer spectroscopy. A series of five powder samples with CoGa x Fe 2−x O 4 compositions ͑x = 0.0-0.8͒ was investigated using transmission geometry. Results show two distinct six-line hyperfine patterns, which are identified as Fe in A ͑tetrahedral͒ and B ͑octahedral͒ spinel sites. Increasing Ga concentration is seen to decrease the hyperfine field strength for both A and B sites, as well as increasing the width of those distributions, consistent with the nonmagnetic nature of Ga 3+ ions. Effects are more pronounced for the B sites than the A sites. Results for Ga substitution show more pronounced effects than for previous studies with Cr 3+ or Mn 3+ substitution: the hyperfine fields decrease and distribution widths increase at greater rates, and the differences between A and B site behavior are more pronounced. Results indicate that at least for the lower Ga concentrations, the Ga 3+ ions substitute predominantly into the A sites, in contrast to Cr 3+ and Mn 3+ which substitute into the B sites. This interpretation is supported by measurements of magnetization at low temperatures. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2834721͔ INTRODUCTIONThe development of cobalt ferrite-based materials has received recent attention for the potential applicability of such materials as magnetoelastic sensors and actuators, and as the magnetoelastic component in composite "multiferroics." 1,2 Substitution of elements such as Mn or Cr for some of the Fe has shown promise of adjusting the magnetic and magnetoelastic properties of these materials through control of chemical composition. 3,4 In order to fully enable the practical applications of these compounds, a more complete family of materials is needed, such that the desired properties can be tailored to a specific application. In the present study, we report on the magnetic characterization of the series of Ga-substituted cobalt ferrites CoGa x Fe 2−x O 4 ͑x = 0.0-0.8͒ as a function of gallium concentration using transmission Mossbauer spectroscopy. The effects of this substitution were expected to be different for Mn and Cr substitution. [5][6][7] EXPERIMENTAL DETAILSThe samples used in this study were prepared at Ames Laboratory, USDOE. The samples were of the composition CoGa x Fe 2−x O 4 ͑where x = 0.0-0.8͒. Standard powder ceramic techniques were employed using Fe 2 O 3 , Ga 2 O 3 , and Co 3 O 4 powders as precursors. The powders were calcined twice, sintered at 1350°C for 24 h, and furnace cooled ͑see Ref. 7 for details͒. The final compositions of the samples were determined by energy-dispersive x-ray spectroscopy, and all samples were confirmed by x-ray powder diffractometry to be single phase and have the cubic spinel ...

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“…A diamagnetic Gallium cation like a Zinc cation replaces a magnetic cation on a tetrahedral site [11][12][13]. In our previous study on MnGa x Fe 2−x O 4 ferrite [13], Ga +3 was found to selectively replace first the Fe +3 cations on A-sites. Room temperature spontaneous magnetization was observed for all x≤0.8 samples.…”

Section: Resultsmentioning

confidence: 92%

Effect of preparation conditions on chemical order and magnetic properties in MnFe2O4 and MnGa1Fe1O4

2006

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Effect of preparation conditions on structural and magnetic properties of Mn and Mn-Ga spinels was investigated by Mössbauer spectroscopy and magnetization measurements. These properties were found to be significantly dependent on the quenching temperature of the samples. Evidently, quenching from elevated temperatures enhanced the magnetization of the spinels due to changes in the chemical short range order.

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Mössbauer studies on MnGaxFe2−xO4

Cited by 10 publications

References 5 publications

Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite

Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite

Investigation of Ga substitution in cobalt ferrite (CoGaxFe2−xO4) using Mossbauer spectroscopy

Effect of preparation conditions on chemical order and magnetic properties in MnFe2O4 and MnGa1Fe1O4

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