Since 2015 we are working at following subproject TP2:
"Vibrational spectroscopy of carbonates at high P and T and deduced structural and thermodynamic properties"
The scientific aim of this project is to determine the phase stability of carbonates at pressures (P) up to 60 GPa and temperatures (T) up to 800 K by vibrational (FTIR- and Raman-) spectroscopy in internally heated diamond anvil cells (DAC-HT). Complementary electronic structure calculations in the framework of density-functional theory (DFT) will be performed to link the atomic and electronic structure of the respective carbonates to their vibrational and thermodynamic properties. We will investigate phase transitions of the carbonate endmembers CaCO3, FeCO3, CaMg(CO3)2 and SrCO3 as well as magnesite-siderite solid solutions.
Fig.: Characteristic Raman spectra of different CaCO3 (cc) polymorphs with increasing pressure (cc-II at 2 GPa; cc-III at 4.1 GPa; cc-IIIb from 5.1 to 11.1 GPa)
Since 2018 we are working at these subprojects
TP8: "Phase relations and melting in the system CaCO3-MgCO3 at high pressure and temperature"
- Determination of the melting curve of magnesite at various pressures under anhydrous and hydrous conditions
- Determination of the sub- and super-solidus phase relations of the CaCO3 – MgCO3 system at 9 GPa and high temperature under anhydrous and hydrous conditions
Prof. Dr. Monika Koch-Müller
Dr. Hans Josef Reichmann
TP9: "Elasticity and structural evolution of carbonates at upper mantle conditions"
The overall objective of this project is to understand the p, T, x-dependence of the elastic stiffness tensor of carbonates up to mantle conditions. This aim will be achieved by a combination of Brillouin scattering, density functional theory calculations, thermal diffuse scattering experiments and inelastic X-ray scattering experiments.
Dr. Sergio Speziale
Prof. Dr. Björn Winkler, Goethe-Universität Frankfurt/Main