High-pressure compressibility and vibrational properties of (Ca,Mn)CO3

Jin Liu , Razvan Caracas (1) , Dawei Fan , Ema Bobocioiu (1) , Dongzhou Zhang , Wendy L. Mao

1 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement

Knowledge of potential carbon carriers such as carbonates is critical for our understanding of the deep-carbon cycle and related geological processes within the planet. Here we investigated the high-pressure behavior of (Ca,Mn)CO3 up to 75 GPa by synchrotron single-crystal X-ray diffraction, laser Raman spectroscopy, and theoretical calculations. MnCO3-rich carbonate underwent a structural phase transition from the CaCO3-I structure into the CaCO3-VI structure at 45-48 GPa, while CaCO3-rich carbonate transformed into CaCO3-III and CaCO3-VI at approximately 2 and 15 GPa, respectively. The equation of state and vibrational properties of MnCO3-rich and CaCO3-rich carbonates changed dramatically across the phase transition. The CaCO3-VI-structured CaCO3-rich and MnCO3-rich carbonates were stable at room temperature up to at least 53 and 75 GPa, respectively. The addition of smaller cations (e.g., Mn2+, Mg2+, and Fe2+) can enlarge the stability field of the CaCO3-I phase as well as increase the pressure of the structural transition into the CaCO3-VI phase.

Mots clés: Carbonate; high pressure; raman spectroscopy; X-ray diffraction

Domaines: Planète et Univers [physics]

Jin Liu, Razvan Caracas, Dawei Fan, Ema Bobocioiu, Dongzhou Zhang, et al.. High-pressure compressibility and vibrational properties of (Ca,Mn)CO3. The American Mineralogist, 2016, 101 (12), pp.2723-2730. ⟨10.2138/am-2016-5742⟩. ⟨hal-02331371⟩