High-pressure-high-temperature phase diagram of CaCO3

Calcium carbonate (CaCO3) and its phase transitions have been extensively studied mainly due to its geological importance. The current proposal is aimed to explore the CaCO3 phase diagram at pressures above 10 GPa and 1400 °C by means of angle-dispersive in situ x-ray diffraction in multianvil press. We propose identifying and characterizing the latest observed unknown phases of CaCO3 (Litasov et al. 2020). Preliminary in-situ x-ray diffraction experiments at HP-HT indicated a potential aragonite’s amorphisation, that needed to be confirmed. We believe that a proper understanding of the CaCO3 phase diagram is fundamental for Earth sciences and, in particular, for the global C cycle.