Pressure-temperature phase boundaries in KC24: Evidence for a kinetically-hindered low-temperature staging transition

• The pressure-temperature phase diagram of KC24 was mapped out using in-plane resistivity anomalies to identify phase boundaries. Surprisingly, the 300-K staging transitions at 3.4 and 6.4 kbar are found to connect to the 1-bar ordering-stacking transitions at Tu=123 K and Tl=96 K, respectively, whereas the loci of P, T anomalies cannot be equilibrium phase boundaries since the low-P, low-T transitions do not involve stage transformations. We suggest that this unusual behavior is due to kinetic hindering of the low-T staging transitions, predicted by simple equilibrium models and observed in the analogous Li compound. A possible origin of the slow staging kinetics at low T in KC24 is the pinning of discommensurations at Daumas-Herold boundaries.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Graphite intercalation compound

GIC

graphite

HOPG

potassium

KC24

stage 2

staging transition

high pressure

low temperature

resistivity

contactless measurements

order-disorder transformation

frustration

kinetic effect

Condensed matter physics

Kondenserade materiens fysik

fysik

Physics

Publikations- och innehållstyp

ref (ämneskategori)

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