TY - JOUR
T1 - The U5+ compound Ba9Ag10U4S24
T2 - Synthesis, structure, and electronic properties
AU - Mesbah, Adel
AU - Stojko, Wojciech
AU - Lebègue, Sébastien
AU - Malliakas, Christos D.
AU - Frazer, Laszlo
AU - Ibers, James A.
N1 - Funding Information:
This research was kindly supported at Northwestern University by the U.S. Department of Energy , Basic Energy Sciences, Chemical Sciences, Biosciences, and Geosciences Division and Division of Materials Science and Engineering Grant ER-15522 . Use was made of the IMSERC X-ray Facility at Northwestern University, supported by the International Institute of Nanotechnology (IIN). S.L. acknowledges HPC resources from GENCI-CCRT/CINES ( Grant x2014-085106 ). L.F. acknowledges Grant NSF IGERT DGE-0801685 .
PY - 2015/1
Y1 - 2015/1
N2 - 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.
AB - 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.
KW - DFT calculations
KW - Resistivity
KW - Single-crystal X-ray structure
KW - Spectroscopy
KW - Synthesis
KW - U
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U2 - 10.1016/j.jssc.2014.10.014
DO - 10.1016/j.jssc.2014.10.014
M3 - Article
AN - SCOPUS:84918540429
VL - 221
SP - 398
EP - 404
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
SN - 0022-4596
ER -