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Title: Gold in the layered structures of R3Au7Sn3: From relativity to versatility

A new isotypic series of ternary rare earth element-gold-tetrel intermetallic compounds has been synthesized and their structures and properties have been characterized. R3Au7Sn3 (R = Y, La-Nd, Sm, Gd-Tm, Lu) crystallize with the hexagonal Gd3Au7Sn3 prototype (Pearson symbol hP26; P63/m, a = 8.110-8.372 Å, c = 9.351-9.609 Å, Vcell = 532.7-583.3 Å3, Z = 2), an ordered variant of the Cu10Sn3-type. Their structure is built up by GdPt2Sn-type layers, which feature edge-sharing Sn@Au6 trigonal antiprisms connected by trigonal R3 groups. Additional insertion of gold atoms leads to the formation of new homoatomic Au clusters, Au@Au6; alternatively, the structure can be considered as a superstructural polyhedral packing of the ZrBeSi-type. The magnetization, heat ca-pacity and electrical resistivity have been measured for R3Au7Sn3 (R = Ce, Pr, Nd and Tb). All four compounds order antiferromagnetically with the highest TN of 13 K for Tb3Au7Sn3. In Ce3Au7Sn3, which has a TN of 2.9 K, the heat capacity and electrical resistivity data in zero and applied fields indicate the presence of Kondo interactions. The coefficient of the linear term in the electronic heat capacity, γ, derived from the heat capacity data below 0.5 K is 211 mJ/Ce mol K2 suggesting strong electronic correlations duemore » to the Kondo interaction. The electronic structure calculations based on the projector augmented wave method for particular representatives of the series suggest different tendencies of the localized R-4f AOs to hybridize with the valence states. LMTO-based bonding analysis on the non-magnetic La3Au7Sn3 indicates that the integrated crystal orbital Hamilton popu-lations (COHPs) are dominated by the heteroatomic Au–Sn contacts; however, contributions from La–Au and La–Sn separations are significant, both together exceeding 40 % in the overall bonding. Furthermore, homoatomic Au–Au interactions are evident for the Au@Au6 units but, despite of the high atomic concentration of Au in the compound, they do not dominate the entire bonding picture.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ;  [1] ;  [3]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States); Univ. of Genova, Genova (Italy); Institute SPIN-CNR, Genova (Italy)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  3. T.I.F.R., Mumbai (India)
Publication Date:
OSTI Identifier:
1321907
Report Number(s):
IS-J--8960
Journal ID: ISSN 1528-7483
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Crystal Growth and Design
Additional Journal Information:
Journal Name: Crystal Growth and Design; Journal ID: ISSN 1528-7483
Publisher:
American Chemical Society
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE complex intermetallics; gold clusters; Kondo interaction; strongly correlated materials; electronic structure calculations