Octahedral cation ordering in olivine at high temperature. II: an in situ neutron powder diffraction study on synthetic MgFeSiO 4 (Fa50)

Redfern, Simon A. T.; Artioli, Gilberto; Rinaldi, Rossella; Henderson, C. M. B.; Knight, Kevin S.; Wood, Bernard J.

doi:10.1007/s002690000109

Cited by 87 publications

(42 citation statements)

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“…The results of the in situ neutron diffraction data published by [5] reveal a distribution similar to the one published by [7]. They observed progressive ordering of Fe 2+ into the M2 site with a crossover at about 900-C for Fe-rich natural olivines [5].…”

Section: Resultssupporting

confidence: 67%

“…Some experimental points reported by [4] are also in a good agreement with the trend of this work. On the other hand, the values of the in situ neutron diffraction studies reported by [7] for synthetic Fa 50 olivine are completely opposite to the results of this work and show a nearly uniform decrease of Fe 2+ at M1 and increase of Fe 2+ at M2 with increasing temperature and with a crossover point near 650-C. The results of [7] are also inconsistent with the results of recent in situ high temperature single crystal X-ray investigations by [8,9] which confirm this study.…”

Section: Resultsmentioning

confidence: 92%

“…A possible crossover at about 350-C leading to reversed ordering (Fe 2+ at M2) at lower temperatures was also discussed. Completely incompatible results for a synthetic Fa 50 olivine were presented by Redfern et al [7] from in situ neutron diffraction experiments between 100 and 1,250-C. The authors presented a set of data that shows an almost uniformly increasing enrichment of Fe 2+ in the M2 site with increasing temperatures between 600 and 1,250-C, whereas at temperatures lower than 600-C Fe 2+ prefers the M1 site.…”

Section: Introductionmentioning

confidence: 76%

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Octahedral cation partitioning in Mg,Fe2+-olivine. Mössbauer spectroscopic study of synthetic (Mg0.5 Fe2+ 0.5)2SiO4 (Fa50)

et al. 2006

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The high-temperature partitioning of Fe 2+ and Mg between the two nonequivalent octahedral M1 and M2 sites in synthetic olivine (Fa 50 ) was studied by Mö ssbauer spectroscopy. Powder samples have been equilibrated in annealing experiments performed under reducing oxygen fugacity at temperatures between 500 and 800-C followed by rapid quenching in order to prevent redistribution of cations. M-site ordering with Fe 2+ preferring M1, Mg preferring M2 sites increases continuously with rising equilibrium temperature. K D values increase from 1.21 at 500-C to 1.48 at 750-C. The results are consistent with both room temperature as well as in situ high temperature single crystal X-ray diffraction experiments of Heinemann et al. [8,9].

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 76%

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Octahedral cation partitioning in Mg,Fe2+-olivine. Mössbauer spectroscopic study of synthetic (Mg0.5 Fe2+ 0.5)2SiO4 (Fa50)

et al. 2006

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“…In order to verify that our experiments produced results that could be compared directly with those from other analysts, we measured the spectra of a suite of synthetic olivines of known specific forsterite composition (Fo 0 , Fo 20 , Fo 30 , Fo 50 and Fo 70 ). The olivines are crystalline, not glassy, and were produced by a method similar to that described by Redfern et al (2000). They were powdered to a homogeneous grain size of at most 1 mm, and the results are shown in Fig.…”

Section: Mineral Grainsmentioning

confidence: 99%

UV-Vis spectroscopy of stardust

Fernandes¹,

Johnson²,

Bridges

et al. 2006

International Journal of Astrobiology

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: NASA's Stardust mission flew through the coma of comet Wild 2 in January 2004, capturing dust grains as it did so. The grains were returned safely to Earth in January 2006, and are in the process of being distributed to investigators. As members of the Spectroscopy Preliminary Examination Team, we are preparing to analyse Stardust grains. Our contribution is to measure the spectrum of the grains between 200 nm (in the near ultraviolet) and 800 nm (near infrared). The purpose of the measurement is to provide an additional technique for characterizing the grains, one that is complementary to other spectroscopic techniques and one that produces results that can be matched directly with spectra acquired remotely (with telescope or spacecraft instrumentation). As part of the preparation for analysis of Stardust materials, we are producing a database of spectra from appropriate minerals, and are honing the technique through analysis of primitive meteorites.

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“…In situ single-crystal neutron diffraction experiments on natural olivines (Fa10 and Fa12) showed that Fe 2+ preferred the M1 site at temperatures up to ∼900 • C, followed by a cross-over and ordering reversal above this temperature [4,5]. Such a trend of cation ordering was also observed in synthetic Fa50 studied by in situ neutron powder diffraction, with the crossover temperature being ∼600 • C [6]. However, recent Mössbauer measurements on synthetic Fa50, annealed at high temperature (500-800 • C) and quenched, showed an increase of order of Fe 2+ at the M1 site with increasing annealing temperature, in agreement with both quenched and in situ single-crystal X-ray diffraction experiments on natural olivines Fa12, Fa25, and Fa48 [7].…”

mentioning

confidence: 68%

High-temperature cation ordering in olivine: an in situ Mössbauer study of synthetic (Mg0.55Fe0.45)2 SiO4

et al. 2008

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High-temperature in situ Mössbauer spectroscopy measurements (300-950 • C) were done on synthetic olivine of composition (Mg 0.55 Fe 0.45 ) 2 SiO 4 (=Fa45) in order to study the distribution of Fe 2+ over the M1 and M2 octahedral sites. The spectra are fit with two doublets, which are assigned to Fe 2+ at the M1 (smaller splitting) and M2 sites. The Fe 2+ site-occupancies at M1 and M2, obtained from the Mössbauer relative areas, suggest that Fe 2+ has a slight preference for the M1 site at temperatures below ∼500 • C, with a tendency of disordering around this temperature. At higher temperatures, Fe 2+ again prefers to occupy the M1 site, where it shows a considerable order at this site up to 750 • C. At still higher temperatures, the spectra indicated partial reduction of the Fa-component into metallic iron and the resolution of the doublets was severely deteriorated.

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Octahedral cation ordering in olivine at high temperature. II: an in situ neutron powder diffraction study on synthetic MgFeSiO 4 (Fa50)

Cited by 87 publications

References 0 publications

Octahedral cation partitioning in Mg,Fe2+-olivine. Mössbauer spectroscopic study of synthetic (Mg0.5 Fe2+ 0.5)2SiO4 (Fa50)

Octahedral cation partitioning in Mg,Fe2+-olivine. Mössbauer spectroscopic study of synthetic (Mg0.5 Fe2+ 0.5)2SiO4 (Fa50)

UV-Vis spectroscopy of stardust

High-temperature cation ordering in olivine: an in situ Mössbauer study of synthetic (Mg0.55Fe0.45)2 SiO4

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