KCu4S3, prepared by the high-temperature reaction of copper, potassium carbonate, and sulfur, crystallizes with a unique layered structure. Double layers of tetrahedrally coordinated (by S) copper ions are separated by layers of potassium ions. Although formally a mixed-valence Cu(I, I, I, II) complex, all copper ions are crystallographically equivalent. Consistent with its Robin and Day class III designation, KCu4S3 exhibits electrical conductivity characteristic of a metal. Room-temperature compaction conductivities of ca. 4000 Ω-1 cm-1 increase to ca. 60000 Ω-1 cm-1 at 20 K. The metallic nature of this two-dimensional material is supported by the temperature-independent paramagnetism and the metallic reflectivity through the visible and near-ultraviolet region of the spectrum.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry