On the Néel temperature of βFeOOH: Structural dependence and its implications

Chambaere, D.; Grave, E. De

doi:10.1016/0304-8853(84)90107-0

Cited by 47 publications

(36 citation statements)

References 9 publications

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“…This value of S agrees with values reported in Ref. 17. However, S is lower than S = 5/2 expected from the application of Hund's rules, as observed in other iron oxides.…”

Section: Bulksupporting

confidence: 80%

“…This compression would then enhance the covalency of the Fe-O bond and consequently diminish the effective 3d spin. 17 This mechanism was proposed by Chambaere and De Grave 17 in order to explain the reduction of the effective spin S observed as the number of interstitial water molecules in the structure was increased.…”

Section: Bulkmentioning

confidence: 99%

“…These channels, parallel to the b axis, are partially occupied by chloride anions which confer stability on the crystal structure. The exchange interactions between Fe 3+ ions in akaganéite result in an antiferromagnetic (AF) material with a Néel temperature T N ∼ 240-299 K. 17 The magnetic cell, proposed from neutron diffraction studies, coincides with the chemical unit cell such that the spins interact antiferromagnetically and are oriented along the b axis. 18 This model was later supported by the results of Mössbauer experiments performed on oriented particles.…”

Section: Sample Characteristicsmentioning

confidence: 99%

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Thermoinduced magnetic moment in akaganéite nanoparticles

et al. 2011

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It is shown that akaganéite β-FeOOH provides a good model material to experimentally investigate thermoinduced magnetic moments in antiferromagnetic nanoparticles. We characterize the magnetic properties, exchange field, anisotropy field, and antiferromagnetic susceptibility of bulk akaganéite. In the nanoparticles, we find a drastic enhancement of the antiferromagnetic susceptibility, a phenomenon first predicted by Néel. Also, we find that akaganéite nanoparticles possess a thermoinduced magnetic moment.

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“…This value of S agrees with values reported in Ref. 17. However, S is lower than S = 5/2 expected from the application of Hund's rules, as observed in other iron oxides.…”

Section: Bulksupporting

confidence: 80%

Section: Bulkmentioning

confidence: 99%

Section: Sample Characteristicsmentioning

confidence: 99%

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Thermoinduced magnetic moment in akaganéite nanoparticles

et al. 2011

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“…The temperatures T B referring to the transition from a pure doublet spectrum to a spectrum in which the onset of magnetic ordering is reflected, were determined by the so-called thermo-scan method. This method measures the ~t-transmission as a function of T with the source having zero velocity (Chambaere and De Grave 1984).…”

Section: Introductionmentioning

confidence: 99%

⁵⁷Fe Mössbauer Effect Study of Al-Substituted Lepidocrocites

Grave

1996

Clays and clay miner.

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Abstract--Seven A|-containing lepidocrocite samples, ~/-Fe,_xAlxOOH, prepared from FeC12/AI(NO3)3 solutions with initial A1/(A1 + Fe) mole ratios C~ of 0.0025, 0.01, 0.025, 0.05, 0.075, 0.10 and 0.15 tool/ mol, were examined by means of M6ssbauer spectroscopy at room temperature (RT) and at various temperatures in the range of 8 to 80 K. The spectra at RT and 80~ consist of broadened quadrupole doublets and were analyzed in terms of a single doublet and of a model-independent quadrupole-splitting distribution, the latter yielding the best fit. The observed variations of the quadrupole-splitting parameters with increasing C i are inconclusive as to whether the A1 cations are substituting into the structure. The temperature at which the onset of magnetic ordering is reflected in the spectra, was measured by the therrnoscan method with zero source velocity. A gradual shift from 50 K for Ci = 0.0025 mol/mol to 44 K for Ci = 0.10 mol/mol was observed for that temperature. As compared to earlier studies of Al-free ~-FeOOH samples with similar morphological characteristics, the fractional doublet area in the mixed sextet-doublet spectra at 35 K is significantly higher for the present lepidocrocites. This observation is ascribed to the substitution of A1 cations into the lepidocrocite structure. A similar conclusion is inferred from the variation with C~ of the maximum-probability hyperfine field derived from the spectra recorded at 8 K and fitted with a model-independent hyperfine-field distribution. The magnetic results suggest that for the sample corresponding to Ci = 0.15 mol/mol, not all of the initially present A1 has been incorporated into the structure.

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“…Therefore the temperature variation of the g-ray transmission through the absorber was recorded as a function of temperature during a fixed time interval with the source at zero velocity [8].…”

Section: Methodsmentioning

confidence: 99%

Mössbauer effect in natural strunzite, ferristrunzite and ferrostrunzite

Alboom

Grave

2005

Hyperfine Interact

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The temperature dependence of the ferric and ferrous hyperfine fields in natural samples of strunzite, ferristrunzite and ferrostrunzite is determined by Mö ssbauer spectroscopy between 4.2 K and their magnetic transition temperatures (T N ), i.e. 50.5T0.5 K, 43.0T0.5 K and 44.0T0.5 K respectively, which are determined by Mö ssbauer thermoscanning. Two dominating magnetically split ferric subspectra were consistently present in all of the samples and are related to the Fe(1) and Fe(2) sites in the crystallographic structure, but an unambiguously assignment to a specific site is not possible. The difference between the corresponding hyperfine fields is very small. In the strunzite sample these fields are well defined and rather weakly dependent of temperature. In the other samples the corresponding hyperfine fields are more distributed especially at higher temperatures (below T N ). The relative contribution in the spectra of the third magnetic ferric component differs strongly between the samples and is assigned to ferric ions at the Mn site. At the lowest temperatures applied, its hyperfine field exceeds all other field values, but it decreases rather rapidly with increasing temperature, in so far that the corresponding spectral lines make a crossover with the lines of the other ferric subspectra. The magnetically split spectra of ferrostrunzite consist additionally of a ferrous magnetic component, which could be successfully analysed by introducing two magnetically split ferrous subspectra, which strongly overlap with each other but also with the ferric components. At higher temperatures in the magnetic region Hyperfine Interact (2005) 166:679-685 all subspectra overlap more and in the case of ferri-and ferrostrunzite the ferric hyperfine fields were distributed over a wider range.

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On the Néel temperature of βFeOOH: Structural dependence and its implications

Cited by 47 publications

References 9 publications

Thermoinduced magnetic moment in akaganéite nanoparticles

Thermoinduced magnetic moment in akaganéite nanoparticles

⁵⁷Fe Mössbauer Effect Study of Al-Substituted Lepidocrocites

Mössbauer effect in natural strunzite, ferristrunzite and ferrostrunzite

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On the Néel temperature of βFeOOH: Structural dependence and its implications

Cited by 47 publications

References 9 publications

Thermoinduced magnetic moment in akaganéite nanoparticles

Thermoinduced magnetic moment in akaganéite nanoparticles

57Fe Mössbauer Effect Study of Al-Substituted Lepidocrocites

Mössbauer effect in natural strunzite, ferristrunzite and ferrostrunzite

Contact Info

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⁵⁷Fe Mössbauer Effect Study of Al-Substituted Lepidocrocites