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Strontianite, Phase diagram, Transition, Infrared, Raman, First principles
Abstract:
Our joint high-pressure and high-temperature mid-infrared absorbance and Raman investigations on a synthetic strontianite sample led to the construction of the respective pressure–temperature P–T phase diagram (maximum P = 38 GPa, maximum T = 800 K). Our results allowed for the determination of the P–T slope for the onset pressure of the aragonite Pmcn → post-aragonite Pmmn structural transition reported in the literature, which is found to be negative and equal to ΔP/ΔT = − 0.012 GPa/K. The determined SrCO3 P–T phase diagram appears consistent with the respective P–T phase diagrams of relevant aragonite-type carbonates. In addition, we provide the first ever measured far-infrared absorbance spectra under pressure for the family of aragonite-type carbonates. Our complementary first-principle calculations were able to reproduce the infrared spectra of both Pmcn and Pmmn phases of strontianite.
