Observation of a reentrant phase transition in incommensurate potassium.
- Resource Type
- Article
- Authors
- Lundegaard, L. F.; Stinton, G. W.; Zelazny, M.; Guillaume, C. L.; Proctor, J. E.; Loa, I.; Gregoryanz, E.; Nelmes, R. J.; McMahon, M. I.
- Source
- Physical Review B: Condensed Matter & Materials Physics. Aug2013, Vol. 88 Issue 5, p054106-1-054106-6. 6p.
- Subject
- *POTASSIUM
*PHASE transitions
*HOST-guest chemistry
*SINGLE crystals
*DIFFRACTION patterns
- Language
- ISSN
- 1098-0121
The phase transitions in the host-guest composite structure of potassium have been determined between 19 and 54 GPa by a combination of x-ray powder and single-crystal diffraction. The guest component of the incommensurate composite phase K-III undergoes an "intraphase" transition at 30.0(7) GPa from a C-centered tetragonal structure to an A-centered orthorhombic form. At 39.7(5) GPa, the guest component undergoes a reentrant transition back to the C-centered tetragonal form. This is the first such reentrant transition observed in the composite structures of the elements. The transition in the guest at 30.0(7) GPa is preceded by a loss of the c-glide symmetry of the host component of the structure, and this is not recovered until some 3 GPa after the reentrant transition at 39.7 GPa. [ABSTRACT FROM AUTHOR]