Anomalous thermophysical properties and electride transition in fcc potassium

Alkali metals undergo an electride transition with excess electrons localized in interstices and acting as anionic interstitial quasi-atoms (ISQs). Less is known about the role of changing their thermophysical properties. Here, taking potassium example, we investigated thermodynamic dynamic properties face-centered cubic (fcc) phase region where occurs when increasing pressure. With help machine-learning-enhanced molecular simulations density functional theory calculations, show property anomalies over a wide pressure range 10--20 GPa but no accompanying structural transformations. Furthermore, find that these solid are stronger at lower temperatures due to more electron-localized nature ISQs. Our findings unveil rich phenomena electrides could deepen our understanding on transition.