Observation of a reentrant phase transition in incommensurate potassium

L. F. Lundegaard, G. W. Stinton, M. Zelazny, C. L. Guillaume, J. E. Proctor, I. Loa, E. Gregoryanz, R. J. Nelmes, M. I. McMahon

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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.

Original languageEnglish
Article number054106
Number of pages6
JournalPhysical review B: Condensed matter and materials physics
Issue number5
Publication statusPublished - 14 Aug 2013



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