Valence fluctuations and metallic behavior in K6Cu12U2S15, a new quaternary sulfide with a unique three-dimensional cubic framework

Anthony C. Sutorik, Rhonda Patschke, Jon Schindler, Carl R. Kannewurf, Mercouri G. Kanatzidis

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Mixed S2-/S1- oxidation states have been discovered in the new quaternary compound K6Cu12U2S15. Synthesized from the reaction of Cu and U in a molten alkali metal/polysulfide flux, the compound crystallizes in the cubic space group Ia3d (no. 230) with a = 18.642(7) Å. Its complex structure is built from [US6] octahedra connected into one-dimensional columns with [CuS3] trigonal planar units, which also serve as inter-column connection points for the extended three-dimensional structure. Magnetic susceptibility measurements reveal Curie - Weiss paramagnetic behavior at temperatures above 100 K with a μeff of 2.96 μB per formula. This corresponds to 2.1 μB per U atom, and it is insufficient to distinguish between U4+ and U5+ paramagnetic ions. The conductivity of hot-pressed polycrystalline pellets is ∼1500 Scm-1 at room temperature, and increasing conductivity with decreasing temperature is observed, indicating metallic behavior for the material. Small and positive values for the material's thermopower (3-4 μV K-1 from 100-300 K) also confirm p-type metallic behavior.

Original languageEnglish
Pages (from-to)1601-1607
Number of pages7
JournalChemistry - A European Journal
Volume6
Issue number9
DOIs
Publication statusPublished - May 2 2000

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Keywords

  • Actinides
  • Conductivity
  • Flux synthesis
  • Metallic sulfides
  • Thermopower
  • Valence fluctuations

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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