Neutron powder diffraction study of the orientational order-disorder phase transition in calcite, CaCO3
Abstract
Neutron powder diffraction studies of calcite on heating towards the orientational order-disorder phase transition show that the phase transition is not a simple analogue of an Ising-like transition, but more similar to a rotational analogue of Lindemann melting. The transition is precipitated by the librational amplitude of the carbonate molecular ions exceeding a critical value rather than a result of a statistical entropy of ‘wrong’ orientations. Using tested interatomic potentials the single-particle orientational potential and nearest-neighbour orientational interactions have been calculated.
- Publication:
-
Physics and Chemistry of Minerals
- Pub Date:
- November 2005
- DOI:
- 10.1007/s00269-005-0026-1
- Bibcode:
- 2005PCM....32..493D