Pressure-induced phase transition of calcite and aragonite: A first principles study

Journal Article · Fri Oct 14 04:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4961723· OSTI ID:22597607

Ukita, Masaya; Toyoura, Kazuaki; Nakamura, Atsutomo ^[1]; Matsunaga, Katsuyuki ^[1]

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1. Department of Materials Science and Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan)

The thermodynamic phase stabilities of calcite and aragonite have been investigated from lattice vibrational analyses based on first-principles calculations. Different pressure dependences in phonon feature were found between the two polymorphs, suggesting different physical origins of the pressure-induced phase transitions. In the most stable phase in calcite (calcite I), an imaginary phonon mode consisting of rotation of CO{sub 3} ions with slight displacement of Ca ions appears at the F point in the Brillouin zone above 0.8 GPa. Such a soft mode means that external pressure induces the lattice-dynamical instability of calcite I leading to the phase transition to calcite II. On the other hand, the origin of the phase transition in aragonite is not due to such a lattice-dynamical instability. The estimated thermodynamical properties indicate that a first-order phase transition occurs between aragonite and post-aragonite at 34.7 GPa, coinciding with the reported experimental value at room temperature (35 GPa).

• OSTI ID: 22597607
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 14 Vol. 120; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ARAGONITE
BRILLOUIN ZONES
CALCITE
CALCIUM IONS
CARBONATES
INSTABILITY
PHASE STABILITY
PHASE TRANSFORMATIONS
PHONONS
PRESSURE DEPENDENCE
PRESSURE RANGE GIGA PA
TEMPERATURE RANGE 0273-0400 K