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Title: Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6

Abstract

Gold intermetallics are known for their unusual structures and bonding patterns. Two new compounds have been discovered in the cation-poor part of the Cs–Au–Ga system. We obtained both compounds directly by heating the elements at elevated temperatures. Structure determinations based on single-crystal X-ray diffraction analyses revealed two structurally and compositionally related formations: CsAu 1.4Ga 2.8 (I) and CsAu 2Ga 2.6 (II) crystallize in their own structure types (I: R$$\bar{3}$$, a = 11.160(2) Å, c = 21.706(4) Å, Z = 18; II: R$$\bar{3}$$, a = 11.106(1) Å, Å, c = 77.243(9) Å, Z = 54) and contain hexagonal cationic layers of cesium. Furthermore, this is a unique structural motif, which has never been observed for the other (lighter) alkali metals in combination with Au and post transition elements. The polyanionic part is characterized in contrast by Au/Ga tetrahedral stars, a structural feature that is characteristic for light alkali metal representatives, and disordered sites with mixed Au/Ga occupancies that occur in both structures with a more significant disorder in the polyanionic component of CsAu 2Ga 2.6. Examinations of the electronic band structure for a model approximating the composition of CsAu 1.4Ga 2.8 have been completed using density-functional-theory-based methods and reveal a deep pseudogap at E F. Bonding analysis by evaluating the crystal orbital Hamilton populations show dominant heteroatomic Au–Ga bonds and only a negligible contribution from Cs pairs.

Authors:
 [1];  [1]; ORCiD logo [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Material Sciences and Engineering
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (EE-5A); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1347910
Report Number(s):
IS-J 9238
Journal ID: ISSN 1528-7483
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Crystal Growth and Design
Additional Journal Information:
Journal Volume: 17; Journal Issue: 2; Journal ID: ISSN 1528-7483
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE

Citation Formats

Smetana, Volodymyr, Steinberg, Simon, and Mudring, Anja-Verena. Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6. United States: N. p., 2016. Web. doi:10.1021/acs.cgd.6b01536.
Smetana, Volodymyr, Steinberg, Simon, & Mudring, Anja-Verena. Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6. United States. doi:10.1021/acs.cgd.6b01536.
Smetana, Volodymyr, Steinberg, Simon, and Mudring, Anja-Verena. Tue . "Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6". United States. doi:10.1021/acs.cgd.6b01536. https://www.osti.gov/servlets/purl/1347910.
@article{osti_1347910,
title = {Layered Structures and Disordered Polyanionic Nets in the Cation-Poor Polar Intermetallics CsAu 1.4 Ga 2.8 and CsAu 2 Ga 2.6},
author = {Smetana, Volodymyr and Steinberg, Simon and Mudring, Anja-Verena},
abstractNote = {Gold intermetallics are known for their unusual structures and bonding patterns. Two new compounds have been discovered in the cation-poor part of the Cs–Au–Ga system. We obtained both compounds directly by heating the elements at elevated temperatures. Structure determinations based on single-crystal X-ray diffraction analyses revealed two structurally and compositionally related formations: CsAu1.4Ga2.8 (I) and CsAu2Ga2.6 (II) crystallize in their own structure types (I: R$\bar{3}$, a = 11.160(2) Å, c = 21.706(4) Å, Z = 18; II: R$\bar{3}$, a = 11.106(1) Å, Å, c = 77.243(9) Å, Z = 54) and contain hexagonal cationic layers of cesium. Furthermore, this is a unique structural motif, which has never been observed for the other (lighter) alkali metals in combination with Au and post transition elements. The polyanionic part is characterized in contrast by Au/Ga tetrahedral stars, a structural feature that is characteristic for light alkali metal representatives, and disordered sites with mixed Au/Ga occupancies that occur in both structures with a more significant disorder in the polyanionic component of CsAu2Ga2.6. Examinations of the electronic band structure for a model approximating the composition of CsAu1.4Ga2.8 have been completed using density-functional-theory-based methods and reveal a deep pseudogap at EF. Bonding analysis by evaluating the crystal orbital Hamilton populations show dominant heteroatomic Au–Ga bonds and only a negligible contribution from Cs pairs.},
doi = {10.1021/acs.cgd.6b01536},
journal = {Crystal Growth and Design},
number = 2,
volume = 17,
place = {United States},
year = {2016},
month = {12}
}

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Works referencing / citing this record:

CSD 1520401: Experimental Crystal Structure Determination: Non-CSD Structure
dataset, December 2016