Contribution à l'étude structurale de la wüstite solide de haute température

Gavarri, J.R.; Carel, C.; Weigel, D.

doi:10.1016/0022-4596(79)90211-1

Cited by 56 publications

(12 citation statements)

References 10 publications

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“…The line closest to the iron-wu¨stite boundary is given by Eq. [26] and the one closest to the wu¨stite-magnetite boundary is given by Eq. [27].…”

Section: Resultsmentioning

confidence: 99%

“…Since the initial work by Vallet et al, the wu¨stite phase field has been probed by many methods to determine whether the pseudo phases exist. Evidence for their existence has been provided by dilatometry, [12][13][14] X-ray diffraction, [12,13,15,16] thermogravimetry, [17][18][19][20][21][22][23][24][25] neutron diffraction, [26] electromotive force, [27,28] and electrical conductivity [29,30] measurements. However, various studies have been conducted that have provided no evidence for the existence of more than one phase in wu¨stite.…”

Section: B Pseudo Phases Of Iron Oxidementioning

confidence: 99%

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Kinetics of the Reaction of CO2/CO Gas Mixtures with Iron Oxide

Worral

Coley

2010

Metall Mater Trans B

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The kinetics of the oxygen exchange reaction between carbon dioxide and carbon monoxide were measured on iron, wu¨stite, and magnetite surfaces. This was done through the use of an isotope exchange technique. The measured rate constants are dependent on the oxygen activity. This dependence is expressed by k a = k o a O Àm . The parameter m was found to have values between 0 and 1. It was found that, in the iron region, the apparent rate constant was independent of the oxygen partial pressure (i.e., m = 0) at 1123 K (850°C) and that it was inversely dependent on the oxygen partial pressure (i.e., m = 1) for the magnetite region at 1123 K (850°C) and 1268 K (995°C). In the wu¨stite region, m was found to be equal to 0.51, 0.66, and 1.0 for the w 1 , w 2 , and w 3 pseudo phases, respectively, at 1268 K (995°C). At 1123 K (850°C), in wu¨stite, m was found to be equal to 0.59 and to 1.0 for the w 1 ¢ and w 3 ¢ pseudo phases, respectively.

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“…The line closest to the iron-wu¨stite boundary is given by Eq. [26] and the one closest to the wu¨stite-magnetite boundary is given by Eq. [27].…”

Section: Resultsmentioning

confidence: 99%

Section: B Pseudo Phases Of Iron Oxidementioning

confidence: 99%

Kinetics of the Reaction of CO2/CO Gas Mixtures with Iron Oxide

Worral

Coley

2010

Metall Mater Trans B

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“…This is why many previous structural studies (Koch & Cohen, 1969;Cheetham, Fender & Taylor, 1971;Catlow & Fender, 1975;Gavarri, Carel & Weigel, 1979;Gavarri, Carel, Jasienska & Janowski, 1981;Gartstein, Mason & Cohen, 1986) have been performed on this material at high temperature or after quenching. It has been shown that the wfistites are characterized by various types of clustering of vacancies (I--l) and interstitial Fe In ions occupying the octahedral (octa) and tetrahedral (tetra) sites respectively of the NaC1 lattice with the general formula:…”

Section: Introductionmentioning

confidence: 99%

“…l(a). However, several other interpretations are possible because of insufficient information provided by the powder diffraction data (Gavarri et al, 1979). The long-range ordering of these clusters of defects in quenched wfistites can now be reexamined taking new experimental and theoretical work into account: (a) Several electron diffraction patterns (Lebreton & Hobbs, 1983) and high-resolution electron microscopy (HREM) images (Iijima, 1974;Ishiguro & Nagakura, 1985 have given clear evidence of defect clustering, probably with a local tetragonal or cubic apparent symmetry.…”

Section: Introductionmentioning

confidence: 99%

The commensurate (10/4) cluster model in quenched wüstite P''. New simulation of HREM direct images

Nihoul¹,

Gavarri²,

Carel³

1991

Acta Crystallogr Sect B

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In the case of non-stoichiometric quenched wfistite P" with the formula Fel-zO (z = 0.096), the defect structure is shown to consist most probably of clusters composed of ten vacancies and four interstitial Fe III ions. These clusters are in agreement with a long-range ordering (2.5X, 2.5X, 5)0, with some disorder in their local arrangement. The direct im~iges of the quenched phase P", previously obtained by various authors, are reinterpreted from a (10/4) cluster model: computer simulations have been carried out using this new model. The simulated images are in good agreement with the experimental images found in the literature.

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“…Aggregation of 4 : 1 clusters is expected because the creation of interstitials in an environment of four vacancies is highly favorable energetically. Neutron diffraction of Fe \V O at high temperatures (9)(10)(11)(12) To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%