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Journal ArticleDOI

IR Spectra, Elastic and Dielectric Properties of Li–Mn Ferrite

18 Oct 2012-International Scholarly Research Notices (Hindawi Publishing Corporation)-Vol. 2012, pp 1-9
TL;DR: Polycrystalline ferrites, , (where and ), were prepared by using ceramic method and single phase cubic structure was confirmed by X-ray diffractometer and the lattice parameter “a” was found to increase with increasing ion substitution.
Abstract: Polycrystalline ferrites, , (where and ), were prepared by using ceramic method. Single phase cubic structure was confirmed by X-ray diffractometer. The lattice parameter “a” was found to increase with increasing ion substitution. IR spectra of the samples were recorded from 200 to 1000 cm−1. The two primary bands corresponding to tetrahedral and octahedral were observed at about 575 cm−1 and 370 cm−1, respectively. Elastic properties of these mixed ferrites were estimated as a function of composition. Young's modulus , rigidity modulus , bulk modulus , Debye temperature (), and mean sound velocity () were calculated from the transverse () and longitudinal () wave velocities. The variation of elastic moduli with composition was interpreted in terms of binding forces between the atoms of spinel lattice. AC conductivity and dielectric properties of the samples were measured at room temperature over 100 Hz–1 MHz. The electrical conduction mechanism could be explained with the electron hopping model. Frequency exponential factor was calculated and it was found between 0.4 and 0.8.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the cation distribution of the spinel system Zn1-xCoxFe2O4 has been investigated by means of X-ray diffraction (XRD), Mossbauer spectroscopy and Fourier transform infrared spectrograph (FTIR).

144 citations

Journal ArticleDOI
TL;DR: In this article, the composition dependent elastic and thermal properties of Li Zn ferrite (Li0.5-x/2ZnxFe2.0) ceramics were reported.

66 citations

Journal ArticleDOI
TL;DR: The single phase cubic spinel structure of the ferrites was confirmed by X-ray diffraction analysis using Transmission Electron Microscopy (TEM) micrographs reveal that the particle size of the samples was in the nanometric range confirming the nano crystalline nature.

47 citations

Journal ArticleDOI
TL;DR: In this paper, the impact of replacing trivalent iron (Fe3+) ions with rare earth europium (RE-Eu3+ ions on the microstructure, optical and magnetic properties of the produced CoFe2O4 nanoparticles was studied.

44 citations

Journal ArticleDOI
TL;DR: The magnetic field and particle-concentration dependent steady-state shear-responses of rod shaped Li-Zn ferrite particle based magnetorheological fluids (MRFs) are reported and, based on the on-state to off-state viscosity ratio (ηon/ηoff), the optimum particle concentration required for energy- and cost-efficient operation of the MRFs can be chosen.
Abstract: We report the magnetic field and particle-concentration dependent steady-state shear-responses of rod shaped Li–Zn ferrite particle based magnetorheological fluids (MRFs). Rod-shaped soft ferrimagnetic Li–Zn ferrite (Li0.4Zn0.2Fe2.4O4) particles were synthesized using the combustion synthesis method. MRFs of three different particle-concentrations (ϕ = 0.1, 0.2 and 0.4, in weight fraction) were prepared using silicone oil. Their yield strength and dynamic viscosity were studied at different applied magnetic fields (B). With an increase in B and ϕ, the yield strength (τY) of the MRFs increases. This behaviour is assigned to the formation of stronger columnar structures of the magnetically interacting particles which resist the flow (shear) of the MRF. For the MRF with ϕ = 0.4 and B = 1.2 T, we observed a maximum τY value of ∼1.25 kPa. Furthermore, we observed that, based on the on-state to off-state viscosity ratio (ηon/ηoff) at a particular operating B value, the optimum particle concentration required for energy- and cost-efficient operation of the MRFs can be chosen. The absence of a stabilizing-agent or de-agglomerating-coating, the low density, and the excellent oxidation- and corrosion-resistance of the soft ferrimagnetic rod-shaped Li–Zn ferrite particles make this MRF-system highly versatile and economical for many magneto-mechanical applications.

38 citations

References
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Journal ArticleDOI

40,330 citations


"IR Spectra, Elastic and Dielectric ..." refers background in this paper

  • ...It has been shown that the presence of Fe ions in ferrites can cause splitting of or produce shoulders on the absorption bands [18]....

    [...]

Book
01 Jan 1940
TL;DR: The Fermi Glass and the Anderson Transition as discussed by the authorsermi glass and Anderson transition have been studied in the context of non-crystalline Semiconductors, such as tetrahedrally-bonded semiconductors.
Abstract: 1. Introduction 2. Theory of Electrons in a Non-Crystalline Medium 3. Phonons and Polarons 4. The Fermi Glass and the Anderson Transition 5. Liquid Metals and Semimetals 6. Non-Crystalline Semiconductors 7. Tetrahedrally-Bonded Semiconductors - Amorphous Germanium and Silicon 8. Aresnic and Other Three-Fold Co-ordinated Materials 9. Chalcogenide and Other Glasses 10. Selenium, Tellurium, and their Alloys

8,188 citations


"IR Spectra, Elastic and Dielectric ..." refers background in this paper

  • ...The conductivity is a complex quantity [32]: σ̃ = σ ′ + iσ ′′....

    [...]

  • ...Pike [37] and Elliott [38] considered s ≤ 1 and it is expressed by the following relation [32, 38]: s = 1− 4 ln (...

    [...]

  • ...Because hopping conduction mechanism was assumed for the Li-Mn ferrites, the ACconductivity σ̃(ω) can be represented by a power law [32]: σ̃(ω)αAω, (16)...

    [...]

Journal ArticleDOI
C. G. Koops1
TL;DR: In this paper, the ac resistivity and the apparent dielectric constant of the material show a dispersion which can be explained satisfactorily with the help of a simple model of the solid: there should be wellconducting grains separated by layers of lower conductivity.
Abstract: Semiconducting ${\mathrm{Ni}}_{0.4}$${\mathrm{Zn}}_{0.6}$${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$, prepared in different ways, has been investigated. It appeared that the ac resistivity and the apparent dielectric constant of the material show a dispersion which can be explained satisfactorily with the help of a simple model of the solid: there should be well-conducting grains separated by layers of lower conductivity. Dispersion formulas are given. There is good agreement between experiment and theory.

2,915 citations


"IR Spectra, Elastic and Dielectric ..." refers methods in this paper

  • ...The dispersion in σ̃ with frequency has been explained by Koops theorem [31], which supposed that the ferrite compact acts as a multilayer capacitor....

    [...]

Journal ArticleDOI
TL;DR: In this article, the infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}{2}{\mathrm {O}}_{4}, where $M$ designates a divalent metal, are presented and analyzed.
Abstract: The infrared spectra of 7 ferrites of the formula $M{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, where $M$ designates a divalent metal, are presented and analyzed. Electronic absorption was observed in the visible and near-infrared regions. Two absorption bands arising from interatomic vibrations were measured and force constants calculated for the stretching of bonds between octahedral or tetrahedral metal ions and oxide ions. These force constants are in agreement with the elastic and thermodynamic properties of these compounds and are sensitive to distribution of metal ions between the alternate sites. The integrated vibrational band intensities were measured: they are compatible with predominantly ionic bonding for these structures.

1,957 citations


"IR Spectra, Elastic and Dielectric ..." refers background or methods in this paper

  • ...The Debye temperature θD can be calculated using the following relation [20]: θD = Cνav k , (5)...

    [...]

  • ...But according to Waldron [20], for isotropic materials with cubic symmetry like spinel ferrites and garnets, C11 ≈ C12, therefore, B = C11....

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  • ...The force constant can be calculated for tetrahedral site (kt) and octahedral site (ko) by using the method suggested by Waldron [20]: Kt = 7....

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  • ...The threshold frequency υth for the electronic transition can be determined from the maximum point of the absorption spectra [20]....

    [...]

  • ...It is observed that the Debye temperature θD calculated according to Waldron equation (5) is higher than that calculated according to Anderson’s formula θ′D (9), but both of them decrease with increasing manganese substitution....

    [...]

Journal ArticleDOI
TL;DR: Mott and Davis as mentioned in this paper proposed the theory of electrons in a non-crystalline medium and its application to liquid metals, amorphous semimetals and semiconductors.
Abstract: N F Mott and E A Davis London: Oxford University Press 1971 pp xiii + 437 price £750 It is hard to think of a physicist other than Professor Mott who would be able to attempt successfully a book of such a broad compass and in Dr Davis, a specialist in the field of amorphous semiconductors, he has found an ideal co-author. The book is divided into two parts: the first deals with the theory of electrons in a noncrystalline medium and its application to liquid metals, amorphous semimetals and semiconductors.

1,062 citations