STRUCTURAL CHANGES AND VALENCE STATES IN THE MGCR2O4-FECR2O4 SOLID SOLUTION SERIES
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dc.contributor.author | Lenaz D. | |
dc.contributor.author | Princivalle F. | |
dc.contributor.author | Skogby H. | |
dc.contributor.author | Hålenius U. | |
dc.date.accessioned | 2022-11-12T08:29:18Z | |
dc.date.available | 2022-11-12T08:29:18Z | |
dc.date.issued | 2004 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=27996414 | |
dc.identifier.citation | Physics and Chemistry of Minerals, 2004, 31, 9, 633-642 | |
dc.identifier.issn | 0342-1791 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/39665 | |
dc.description.abstract | The influence on the structure of Fe2+ → Mg substitution was studied in synthetic single crystals belonging to the MgCr2O4–FeCr2O4 series produced by flux growth at 900–1200 °C in controlled atmosphere. Samples were analyzed by single-crystal X-ray diffraction, electron microprobe analyses, optical absorption-, infrared- and Mössbauer spectroscopy. The Mössbauer data show that iron occurs almost exclusively as IVFe2+. Only minor Fe3+ (<0.005 apfu) was observed in samples with very low total Fe. Optical absorption spectra show that chromium with few exceptions is present as a trivalent cation at the octahedral site. Additional absorption bands attributable to Cr2+ and Cr3+ at the tetrahedral site are evident in spectra of end-member magnesiochromite and solid-solution crystals with low ferrous contents. Structural parameters a 0, u and T–O increase with chromite content, while the M–O bond distance remains nearly constant, with an average value equal to 1.995(1) Å corresponding to the Cr3+ octahedral bond distance. The ideal trend between cell parameter, T–O bond length and Fe2+ content (apfu) is described by the following linear relations: a 0=8.3325(5) + 0.0443(8)Fe2+ (Å) and T–O=1.9645(6) + 0.033(1)Fe2+ (Å) Consequently, Fe2+ and Mg tetrahedral bond lengths are equal to 1.998(1) Å and 1.965(1) Å, respectively. | |
dc.subject | MgCr2O4 | |
dc.subject | FeCr2O4 | |
dc.subject | spinels | |
dc.subject | Single-crystal XRD | |
dc.subject | EPMA | |
dc.subject | OAS | |
dc.subject | Mossbauer | |
dc.title | STRUCTURAL CHANGES AND VALENCE STATES IN THE MGCR2O4-FECR2O4 SOLID SOLUTION SERIES | |
dc.type | Статья |
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