We investigated the behavior of MnCO3 in the pressure range 0-50 GPa and ambient temperature by synchrotron X-ray single-crystal diffraction technique. MnCO3 maintains the calcite-type structure (R3c symmetry) up to 44 GPa. Above this pressure we observed a phase transition. The highpressure phase, MnCO3-II, is triclinic, with cell parameters a = 2.928(2), b = 4.816(4), c = 5.545(4) Å, α = 101.71(6)°, β = 94.99(6)°, γ = 89.90(6)°, and V = 76.28(10) Å3 at 46.8 GPa. The structure is solved with the charge flipping algorithm. MnCO3-II is isostructural with CaCO3-VI. The density increase on phase transition is 4.4%. The occurrence of CaCO3-VI structure in MnCO3 composition indicates that CaCO3-VI structure is also adopted by carbonates with cations smaller than calcium.
The MnCO3-II high-pressure polymorph of rhodocrosite / M. Merlini, M. Hanfland, M. Gemmi. - In: AMERICAN MINERALOGIST. - ISSN 0003-004X. - 100:11/12(2015), pp. 2625-2629.
Titolo: | The MnCO3-II high-pressure polymorph of rhodocrosite |
Autori: | GEMMI, MAURO (Ultimo) |
Parole Chiave: | carbonates; high-pressure crystal structure; rhodocrosite; single crystal; geochemistry and petrology; geophysics |
Settore Scientifico Disciplinare: | Settore GEO/06 - Mineralogia |
Data di pubblicazione: | 2015 |
Rivista: | |
Tipologia: | Article (author) |
Digital Object Identifier (DOI): | http://dx.doi.org/10.2138/am-2015-5320 |
Appare nelle tipologie: | 01 - Articolo su periodico |
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