Mössbauer resonance of Fe57 in oxidic spinels containing Cu and Fe

Evans, Bernard W.; Hafner, S. S.

doi:10.1016/0022-3697(68)90100-5

Cited by 230 publications

(67 citation statements)

References 30 publications

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“…For the octahedral site (B-site), the band t 2 * shifted to lower frequency; the two bands m 3 and m 4 shifted to lower values of wave number at 355 and 380 cm -1 (for T a = 1,000°C) and shifted to higher frequencies at T a = 1,200°C. Figure 6 shows the behaviour of the primary bands of the tetrahedral site t 1 * and the octahedral site t 2 * with increasing the annealing temperature (from 800 up to 1,200°C (Evans and Hafner 1968).…”

Section: Resultsmentioning

confidence: 99%

Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

Mazen

Abu-Elsaad

2014

Appl Nanosci

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The physical properties of ferrites are very sensitive to microstructure, which in turn critically depends on the manufacturing process. Lithium ferrite is synthesized by milling process. The powder was annealed at four different temperatures 600, 800, 1,000 and 1,200°C. The powder annealed at 600°C has the spinel structure with some of a-Fe 2 O 3 , while the powders annealed at C800°C formed in single-phase cubic spinel structure. Particle size of lithium ferrite is in the range of 26-70 nm, and is dependent on the annealing temperature. The saturation magnetization increased from 22 to 85 emu/g and the coercivity decreases from 124 to 4 Oe with increase in the annealing temperature. The dielectric constant (e'), dielectric loss (tan d) and ac conductivity (r ac ) were measured at room temperature as a function of frequency. The results of dielectric properties were explained in terms of Koops phenomenological theory.

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Section: Resultsmentioning

confidence: 99%

Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

Mazen

Abu-Elsaad

2014

Appl Nanosci

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“…The values of ν * 1 are higher than those of ν * 2 , indicating that the normal mode of vibration of the tetrahedral complexes is higher than that of the corresponding octahedral site. This may be due to the shorter bond length of the tetrahedral site (R A = 1.89Å) than that of the octahedral site (R B = 1.99Å) [15]. From Table 1 it is obvious that by introducing Mn 2+ , the band υ * 1 shifts slightly towards lower frequency meanwhile the band υ * 2 has no shift or change with frequency.…”

Section: Introductionmentioning

confidence: 96%

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

Mazen

Abu-Elsaad

2012

ISRN Condensed Matter Physics

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Polycrystalline ferrites, Li 0.5-0.5x Mn x Fe 2.5-0.5x O 4 , (where x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0), 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 Mn 2+ ion substitution. IR spectra of the samples were recorded from 200 to 1000 cm −1 . The two primary bands corresponding to tetrahedral υ A and octahedral υ B 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 (E), rigidity modulus (G), bulk modulus (B), Debye temperature (θ D ), and mean sound velocity (V m ) were calculated from the transverse (V t ) and longitudinal (V 1 ) wave velocities. The variation of elastic moduli with composition was interpreted in terms of binding forces between the atoms of spinel lattice. AC conductivity σ 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 (s) was calculated and it was found between 0.4 and 0.8.

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“…For the starting sample S0, two magnetic sextets are observed at both temperatures, which are identical to those of Fe 3ϩ ions in tetrahedral ͑Bϭ50.5 T at 4.2 K͒ and octahedral ͑Bϭ53.7 T at 4.2 K͒ sites of the CuFe 2 O 4 spinel. 3 After 3 h, the sextets almost collapse at 296 K and a central doublet with broad lines appears. The spectrum can be fitted using two doublets and a tiny broadened sextet with an average hyperfine field of 43.6 T. The isomer shifts for the three subspectra infer that only Fe 3ϩ ions exist in the sample.…”

Section: Methodsmentioning

confidence: 99%

“…The ideal inverse configuration consists of eight divalent (Cu 2ϩ ͒ ions on the octahedral ͑B͒ sites and 16 trivalent (Fe 3ϩ ͒ ions equally splitting between the tetrahedral ͑A͒ and B sites per unit cell. It is ferrimagnetic at room temperature with Néel temperature of 780͑20͒ K, 3 although lower values down to 710 K have also been reported. 4 The magnetization of the A sublattice is antiparallel to that of the B sublattice, whereas magnetic moments of the ions on the A and B sublattices are ferromagnetically ordered.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of ball milled copper ferrite

Goya

Rechenberg

Jiang

1998

Journal of Applied Physics

178

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The structural and magnetic evolution in copper ferrite (CuFe 2 O 4 ͒ caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe 2 O 4 to about 6 nm and induces cation redistribution between A and B sites. These nanometer-sized particles show superparamagnetic relaxation effects at room temperature. It is found that the magnetization is not saturated even with an applied field of 9 T, possibly as the result of spin canting in the partially inverted CuFe 2 O 4 . The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized CuFe 2 O 4 particles decompose, forming ␣-Fe 2 O 3 and other phases, causing a further decrease of magnetization. After a milling time of 98 h, ␣-Fe 2 O 3 is reduced to Fe 3 O 4 , and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: ͑a͒ the synthesis of partially inverted CuFe 2 O 4 particles with a noncollinear spin structure, ͑b͒ the decomposition of the starting CuFe 2 O 4 onto several related Fe-Cu-O phases, and ͑c͒ the reduction of ␣-Fe 2 O 3 to Fe 3 O 4 .

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Mössbauer resonance of Fe57 in oxidic spinels containing Cu and Fe

Cited by 230 publications

References 30 publications

Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

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

Structural and magnetic properties of ball milled copper ferrite

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