Discovery of Elusive K 4 O 6 , a Compound Stabilized by Configurational Entropy of Polarons.

Publisher: Wiley-VCH Country of Publication: Germany NLM ID: 0370543 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1521-3773 (Electronic) Linking ISSN: 14337851 NLM ISO Abbreviation: Angew Chem Int Ed Engl Subsets: PubMed not MEDLINE

Publication: <2004-> : Weinheim : Wiley-VCH
Original Publication: Weinheim/Bergstr. : New York, : Verlag Chemie ; Academic Press, c1962-

Synthesis of elusive K 4 O 6 has disclosed implications of crucial relevance for new solid materials discovery. K 4 O 6 forms in equilibrium from K 2 O 2 and KO 2 , in an all-solid state, endothermic reaction at elevated temperature, undergoing back reaction upon cooling to ambient conditions. This tells that the compound is stabilized by entropy alone. Analyzing possible entropic contributions reveals that the configurational entropy of "localized" electrons, i.e., of polaronic quasi-particles, provides the essential contribution to the stabilization. We corroborate this assumption by measuring the relevant heats of transformation and tracking the origin of entropy of formation computationally. These findings challenge current experimental and computational approaches towards exploring chemical systems for new materials by searching the potential energy landscape: one would fail in detecting candidates that are crucially stabilized by the configurational entropy of localized polarons.
(© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Keywords: density functional theory; entropy; mixed valent compounds; solid-state reactions

Date Created: 20181009 Latest Revision: 20191120

20250114

10.1002/anie.201809409

30294899