The U5+ compound Ba9Ag10U4S24: Synthesis, structure, and electronic properties

Adel Mesbah, Wojciech Stojko, Sébastien Lebègue, Christos D. Malliakas, Laszlo Frazer, James A. Ibers*

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Black crystals of Ba9Ag10U4S24 have been made by direct combination of BaS, Ag, U, and S at 1273 K. This compound crystallizes in a new structure type in the space group C4v10-I4cm of the tetragonal system with four formula units in a cell with lattice constants a=13.9189(6) Å and c=23.7641(11) Å (V=4604(5) Å3). Multiphoton Luminescence Spectroscopy measurements are consistent with the noncentrosymmetric nature of the structure. In the structure each U atom is octahedrally coordinated by six S atoms, whereas three of the five crystallographically independent Ag atoms are tetrahedrally coordinated to four S atoms, another has a seesaw coordination to four S atoms, and the last has a triangular coordination to three S atoms. The overall structure consists of the three-dimensional stacking of the US6, AgS4, and AgS3 polyhedra to leave channels in which Ba atoms reside. Based on the values of the U-S interatomic distances, the compound Ba9Ag10U4S24 contains U5+ and charge balance is achieved with the formal oxidation states of 9 Ba2+, 10 Ag1+, 4 U5+ and 24 S2-. DFT calculations predict an antiferromagnetic ground state and a band gap of 2.1 eV. Resistivity measurements indicate that the compound is a semiconductor with a complex activation mechanism and activation energies ranging from 0.03(1) eV to 0.08(1) eV.

Original languageEnglish (US)
Pages (from-to)398-404
Number of pages7
JournalJournal of Solid State Chemistry
Volume221
DOIs
StatePublished - Jan 2015

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Keywords

  • DFT calculations
  • Resistivity
  • Single-crystal X-ray structure
  • Spectroscopy
  • Synthesis
  • U

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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