High-pressure phase behavior of SrCO3: an experimental and computational Raman scattering study

The high-pressure phase behavior of strontianite (SrCO3) was both experimentally and theoretically investigated by Raman spectroscopy up to 78 GPa in a diamond anvil cell and density functional theory-based calculations. Our study shows a phase transition between 23.7 and 26.8 GPa during compression from space group Pmcn to post-aragonite SrCO3, which is accompanied by significant changes in the vibrational spectrum. The excellent agreement between the observed and computed Raman frequencies and intensities implies that the high-pressure polymorph has space group Pmmn and contributes to resolving an existing disagreement concerning the correct space group symmetry of this high-pressure polymorph. It is shown that the transition pressure from the aragonite to a post-aragonite phase increases linearly with decreasing cation radius for (Ca, Sr, Ba, Pb) carbonates.