Raman spectroscopic study of calcite III to aragonite transformation under high pressure and high temperature

ABSTRACT

In our study, a series of Raman experiments on the phase transition of calcite at high pressure and high temperature were investigated using a hydrothermal diamond anvil cell and Raman spectroscopy technique. It was found that calcite I transformed to calcite II and calcite III at pressures of 1.62 and 2.12 GPa and room temperature. With increasing temperature, the phase transition of calcite III to aragonite occurred. Aragonite was retained upon slowly cooling of the system, indicating that the transition of calcite III to aragonite was irreversible. Based on the available data, the phase boundary between calcite III and aragonite was determined by the following relation: P(GPa) = 0.013 × T(°C) + 1.22 (100°C ≤ T ≤ 170°C). It showed that the transition pressure linearly rose with increasing temperature. A better understanding of the stability of calcite III and aragonite is of great importance to further explore the thermodynamic behavior of carbonates and carbon cycling in the mantle.

KEYWORDS:

• Calcite III
• aragonite
• high pressure
• phase transition
• Raman spectroscopy

Acknowledgements

The authors are very grateful to Professor Kagi and the anonymous reviewer for their constructive and valuable comments on our manuscript. We also wish to thank J.Q. Ren for his assistance to the Raman spectroscopy measurement in our experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Natural Science Foundation of China [grant number 41603061] and the CAS/CAFEA international partnership program for creative research teams [grant number KZZD-EW-TZ-19].