Raman spectroscopy and x-ray diffraction of sp3 CaC O3 at lower mantle pressures

Sergey S. Lobanov, Xiao Dong, Naira S. Martirosyan, Artem I. Samtsevich, Vladan Stevanovic, Pavel N. Gavryushkin, Konstantin D. Litasov, Eran Greenberg, Vitali B. Prakapenka, Artem R. Oganov, Alexander F. Goncharov

Результат исследования: Научные публикации в периодических изданияхстатья

17 Цитирования (Scopus)

Аннотация

The exceptional ability of carbon to form sp2 and sp3 bonding states leads to a great structural and chemical diversity of carbon-bearing phases at nonambient conditions. Here we use laser-heated diamond-anvil cells combined with synchrotron x-ray diffraction, Raman spectroscopy, and first-principles calculations to explore phase transitions in CaCO3 at P>40GPa. We find that postaragonite CaCO3 transforms to the previously predicted P21/cCaCO3 with sp3-hybridized carbon at 105 GPa (∼30GPa higher than the theoretically predicted crossover pressure). The lowest-enthalpy transition path to P21/cCaCO3 includes reoccurring sp2 and sp3CaCO3 intermediate phases and transition states, as revealed by our variable-cell nudged-elastic-band simulation. Raman spectra of P21/cCaCO3 show an intense band at 1025cm-1, which we assign to the symmetric C-O stretching vibration based on empirical and first-principles calculations. This Raman band has a frequency that is ∼20% lower than the symmetric C-O stretching in sp2CaCO3 due to the C-O bond length increase across the sp2-sp3 transition and can be used as a fingerprint of tetrahedrally coordinated carbon in other carbonates.

Язык оригиналаанглийский
Номер статьи104101
Число страниц9
ЖурналPhysical Review B
Том96
Номер выпуска10
DOI
СостояниеОпубликовано - 1 сен 2017

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  • Цитировать

    Lobanov, S. S., Dong, X., Martirosyan, N. S., Samtsevich, A. I., Stevanovic, V., Gavryushkin, P. N., Litasov, K. D., Greenberg, E., Prakapenka, V. B., Oganov, A. R., & Goncharov, A. F. (2017). Raman spectroscopy and x-ray diffraction of sp3 CaC O3 at lower mantle pressures. Physical Review B, 96(10), [104101]. https://doi.org/10.1103/PhysRevB.96.104101