Raman study of MgCO3-FeCO3 carbonate solid solution at high pressures up to 55 GPa

Magnesite, siderite and ferromagnesites Mg1-x Fe (x) CO3 (x = 0.05, 0.09, 0.2, 0.4) were characterized using in situ Raman spectroscopy at high pressures up to 55 GPa. For the Mg-Fe-carbonates, the Raman peak positions of six modes (T, L, nu(4), nu(1), nu(3) and 2 nu(2)) in the dependence of iron content in the carbonates at ambient conditions are presented. High-pressure Raman spectroscopy shows that siderite undergoes a spin transition at similar to 40 GPa. The examination of the solid solutions with compositions Mg0.6Fe0.4CO3, Mg0.8Fe0.2CO3, Mg0.91Fe0.09CO3 and Mg0.95Fe0.05CO3 indicates that with increase in the amount of the Fe spin transition pressure increases up to similar to 45 GPa.