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Structural and chemical characterization of Mg[(Cr,Mg)(Si,Mg)]O4, a new post-spinel phase with sixfold-coordinated siliconстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 29 сентября 2015 г.
- Авторы: Bindi L., Sirotkina E.A., Bobrov A.V., Irifune T.
- Журнал: American Mineralogist
- Том: 100
- Год издания: 2015
- Издательство: Mineralogical Society of America
- Местоположение издательства: United States
- DOI: 10.2138/am-2015-5322
- Аннотация: The crystal structure and chemical composition of a crystal of Mg(Mg,Cr,Si)2O4 post-spinel phase synthesized in the model system MgCr2O4–Mg2SiO4 at 16 GPa and 1600 °C have been investigated. The compound was found to crystallize with a distorted orthorhombic calcium-titanate (CaTi2O4) structure type, space group Cmc21, with lattice parameters a = 2.8482(1), b = 9.4592(5), c = 9.6353(5) Å, V = 259.59(1) Å3, and Z = 4. The structure was refined to R1 = 0.018 using 345 independent reflections. The loss of the inversion center is due to the ordering of cations at the octahedral sites: Cr is mainly hosted at the M1 site, whereas Si at the M2 site. Such an ordered distribution induces a distortion thus provoking a change in coordination of Mg, which becomes sevenfold-coordinated instead of the usual eightfold coordination observed in post-spinel phases. Electron microprobe analysis gave the Mg[(Cr0.792Mg0.208) (Si0.603Mg0.397)]O4 stoichiometry for the studied phase. The successful synthesis of this phase can provide new constraints on thermobarometry of wadsleyite/ringwoodite-bearing assemblages.
- Добавил в систему: Бобров Андрей Викторович