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Updated: May 7, 2026
09:31
Calcium Carbonate Formation in the Presence of Biopolymeric Additives
Published on: May 14, 2019
Structural evolution of calcite at high temperatures: phase V unveiled
Nobuo Ishizawa1, Hayato Setoguchi, Kazumichi Yanagisawa
1Advanced Ceramics Research Center, Nagoya Institute of Technology, 10-6-29 Asahigaoka, Tajimi, 507-0071, Japan.
Scientific Reports
|October 3, 2013
Summary
Calcium carbonate (CaCO₃) undergoes a reversible phase transition at high temperatures. Oxygen atoms in the high-temperature phase exhibit dynamic migration, revealing insights into crystal structure changes.
Area of Science:
- Crystallography
- Materials Science
- Geochemistry
Background:
- Calcite (CaCO₃) is a common mineral with a well-defined crystal structure.
- Phase transitions in minerals are crucial for understanding geological processes and material properties.
- Previous studies have indicated phase transitions in CaCO₃ at elevated temperatures and pressures.
Purpose of the Study:
- To investigate the reversible phase transition of calcite (CaCO₃) at approximately 1240 K.
- To elucidate the dynamic behavior of carbonate (CO₃) groups in the high-temperature phase of CaCO₃.
- To characterize the intermediate phase (Phase IV) formed during the transition from room temperature (Phase I) to the high-temperature phase (Phase V).
Main Methods:
- Single-crystal X-ray diffraction was employed to collect crystallographic data.
- Analysis of the joint probability density function was used to determine atomic positions and dynamics.
- Temperature-dependent studies were conducted under a controlled carbon dioxide (CO₂) atmosphere.
Main Results:
- A reversible phase transition between space groups Rc and Rm was observed at ~1240 K under 0.4 MPa CO₂.
- In the high-temperature phase (Phase V), oxygen atoms within the carbonate groups exhibit dynamic migration along circular orbitals around the central carbon atom.
- An intermediate phase (Phase IV) was identified between ~985 K and ~1240 K, representing a transitional state from Phase I to Phase V.
Conclusions:
- The calcite phase transition involves significant dynamic disorder in the carbonate group at high temperatures.
- Understanding these dynamic processes is key to comprehending the behavior of calcium carbonate under various conditions.
- The identified intermediate phase provides a more complete picture of the calcite phase transformation pathway.
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