Cover Picture: Discovery of Elusive K₄O₆, a Compound Stabilized by Configurational Entropy of Polarons (Angew. Chem. Int. Ed. 1/2019)

Discovery of elusive K4O6 an endothermic mixed peroxide–superoxide compound: In the Communication on page 149, M. Jansen et al. report on the synthesis of K4O6 that owes its stability to the configurational entropy of polarons, and thus exists only above a distinct temperature threshold. The puzzling speed at which the all-solid-state reactions of formation and decomposition proceed, as a function of temperature, are illustratively documented by a real-time video.