Magnetic and thermal properties of ε-Fe2O3

Dézsi, I.; Coey, J. M. D.

doi:10.1002/pssa.2210150239

Cited by 56 publications

(28 citation statements)

References 8 publications

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“…Trautmann and Forestier (6) reported the preparation of pure -Fe O by boiling an aqueous mixture of potassium ferricyanide, sodium hypochlorite, and potassium hydroxide and heating the precipitate at 400°C. Using similar conditions, De´zsi and Coey (7) To whom correspondence should be addressed. Fax: #33 1 44 27 47 69.…”

Section: -Fementioning

confidence: 88%

“…Viart et al (8) recently obtained fine particles of -Fe O , mixed with hematite, by heating silica xerogels impregnated with a solution of iron nitrate. Transformation of -Fe O into hematite under heating was reported to take place at 500-750°C according to the preparation method (3)(4)(5)(6)(7). Magnetic studies (4,6) of the bulk material concluded to ferrimagnetic properties with a Curie temperature of ca.…”

Section: -Fementioning

confidence: 97%

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Structural and Magnetic Characterization ofε-Fe2O3

Tronc

Chanéac

Jolivet

1998

Journal of Solid State Chemistry

283

234

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Section: -Fementioning

confidence: 88%

Section: -Fementioning

confidence: 97%

Structural and Magnetic Characterization ofε-Fe2O3

Tronc

Chanéac

Jolivet

1998

Journal of Solid State Chemistry

283

234

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“…above the  →  transition. This transitions occurs, depending on heating rate and -Fe 2 O 3 crystal size, between 750 and 825°C (Dézi and Coey, 1973;Brázda et al, 2014). A possible conversion to haematite can therefore not be excluded in our case.…”

Section: Discussionmentioning

confidence: 81%

“…As this slope change occurs in both heating and cooling curves it may me associated with the Curie temperature (T C ) of -Fe 2 O 3 , a metastable iron oxide phase with reported T C between 207 and 237°C (e.g. Dézi and Coey, 1973;Popovici et al, 2004;Tuček et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Archaeomagnetic investigations in Bolgar (Tatarstan)

et al. 2020

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The objective of this study is to provide a well-dated point for a future palaeosecular variation (PSV) reference curve for western Russia. For this purpose archaeomagnetic and magnetic property analyses were carried out on a pottery kiln unearthed at the UNESCO World Heritage site of ancient Bolgar, having a rather precise age dating. The archaeological context provided an age between 1340 and 1360 C.E. The characteristic remanence vector was determined through alternating field demagnetisation and Thellier-Thellier palaeointensity experiments. Some innovations were introduced regarding palaeointensity. The check testing the equality of blocking and unblocking temperature was redefined. This allowed waiving the commonly used additional zero-field cooling steps during the Thellier-Thellier experiment. Another innovation concerns the calculation of archaeointensity at structure level. A Bayesian approach was introduced for averaging individual specimen archaeointensities using a prior probability distribution of unknown uncertainties. Next, an additional prior probability distribution was used to correct for cooling rate effects. This resulted in a lower uncertainty compared to common practice and in eluding time consuming cooling rate experiments. The complex magnetic mineralogy consists of maghaemite, multi-domain haematite and Al-substituted haematite. Some samples contained also some non-stoichiometric magnetite. The magnetic mineralogy was determined through hysteresis loops, backfield and remanence decay curves, measurements of the frequency-dependent magnetic susceptibility and through low temperature magnetisation curves. Accompanying hightemperature thermomagnetic analyses revealed an excellent thermo-chemical stability of the studied specimens. Directions obtained from alternating field demagnetisation and those extracted from archaeointensity experiments are congruent and have low uncertainties. The obtained archaeomagnetic results are fairly in agreement with global geomagnetic field models and contemporary PSV data of the wider area. The

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“…In earlier works, Schrader and Buttner [29] have identified its structure as monoclinic with a = 12.97, b = 10.21, c = 8.44 (in Å) and β =95.66°. Dézsi and Coey [30] report a simpler structure; nevertheless, they also refer to it as ε-Fe 2 O 3 subjected to disorder effects. Tronc, Chanéac and Jolivet [21] have shown that high-temperature heat treatment of γ-Fe 2 O 3 nanoparticles dispersed in silica xerogel gives rise to the formation of ε-Fe 2 O 3 nanoparticles with an average diameter about 30 nm, having orthorhombic structure with a = 5.095, b = 8.789 and c = 9.437 Å.…”

Section: Introductionmentioning

confidence: 99%

Effect of gadolinium on magnetic circular dichroism and electron magnetic resonance of ε-Fe2O3 nanoparticles formed in borate glasses

Édelman

Kliava

Ivanova

et al. 2019

Journal of Non-Crystalline Solids

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A remarkable characteristic of borate glasses is the ability of forming magnetic nanoparticles at low doping with transition element oxides. We have studied structure and magnetic properties of iron oxide nanoparticles formed in borate glasses, in particular, concentration and temperature dependences of magnetic circular dichroism (MCD) and electron magnetic resonance (EMR) spectra. A series of glasses of molar composition 22.5K 2 O-22.5Al 2 O 3-55B 2 O 3 doped with 1.5 mass % of Fe 2 O 3 and different contents of Gd 2 O 3 from 0.1 to 1.0 mass % was prepared using a conventional melt quenching technique and subjected to an additional thermal treatment. The whole set of results allows to identify the predominant magnetic phase in these glasses as ε-Fe 2 O 3 nanoparticles, with a considerable part of iron ions substituted by gadolinium. Analysis and computer simulations of the EMR spectra allow separating the contribution of electron paramagnetic resonance of diluted iron ions and together with the temperature dependences of magnetization demonstrate a superparamagnetic character of the nanoparticle magnetism.

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Magnetic and thermal properties of ε-Fe2O3

Cited by 56 publications

References 8 publications

Structural and Magnetic Characterization ofε-Fe2O3

Structural and Magnetic Characterization ofε-Fe2O3

Archaeomagnetic investigations in Bolgar (Tatarstan)

Effect of gadolinium on magnetic circular dichroism and electron magnetic resonance of ε-Fe2O3 nanoparticles formed in borate glasses

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