High-pressure and high-temperature vibrational properties and anharmonicity of carbonate minerals up to 6 GPa and 500 °C by Raman spectroscopy

Abstract Carbonate minerals play a dominant role in the deep carbon cycle. Determining high-pressure and high-temperature vibrational properties of carbonates is essential to understand their anharmonicity thermodynamic under crustal upper mantle conditions. Building on our previous study aragonite, calcite (both CaCO3 polymorphs), dolomite [CaMg(CO3)2], magnesite (MgCO3), rhodochrosite (MnCO3), siderite (FeCO3) (Farsang et al. 2018), we have measured pressure- temperature-induced frequency shifts Raman-active modes up 6 GPa 500 °C for all naturally occurring aragonite- calcite-group carbonate minerals, including cerussite (PbCO3), strontianite (SrCO3), witherite (BaCO3), gaspeite (NiCO3), otavite (CdCO3), smithsonite (ZnCO3), spherocobaltite (CoCO3). Our Raman XRD measurements show that decomposes mixture Pb2O3 tetragonal PbO between 225 250 °C, breaks down hexagonal ZnO 325 400 NiO 375 °C. Spherocobaltite 425 450 Due thermal stability, may serve as potential reservoirs several metals (e.g., Co, Ni, Zn, Cd) range environments subduction zones). We determined isobaric isothermal equivalents mode Grüneisen parameter anharmonic each compare trends function pressure, temperature, chemical composition with concomitant changes structural properties. Finally, use calculate contribution internal energy entropy, well isochoric heat capacity certain carbonates.