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REAuAl{sub 4}Ge{sub 2} and REAuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2} (RE=rare earth element): Quaternary intermetallics grown in liquid aluminum

Journal Article · · Journal of Solid State Chemistry
OSTI ID:20784755
 [1];  [1]
  1. Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States)

The two families of intermetallic phases REAuAl{sub 4}Ge{sub 2} (1) (RE=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm and Yb) and REAuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2} (2) (x=0.4) (RE=Ce and Eu) were obtained by the reactive combination of RE, Au and Ge in liquid aluminum. The structure of (1) adopts the space group R-3m (CeAuAl{sub 4}Ge{sub 2}, a=4.2384(7)A, c=31.613(7)A; NdAuAl{sub 4}Ge{sub 2}, a=4.2258(4)A, c=31.359(5)A; GdAuAl{sub 4}Ge{sub 2}, a=4.2123(6)A, c=30.994(6)A; ErAuAl{sub 4}Ge{sub 2}, a=4.2074(4)A, c=30.717(5)A). The structure of (2) adopts the tetragonal space group P4/mmm with lattice parameters: a=4.3134(8)A, c=8.371(3)A for EuAuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2} (x=0.4). Both structure types present slabs of ''AuAl{sub 4}Ge{sub 2}'' or ''AuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2}'' stacking along the c-axis with layers of RE atoms in between. Magnetic susceptibility measurements indicate that the RE atoms (except for Ce and Eu) possess magnetic moments consistent with +3 species. The Ce atoms in CeAuAl{sub 4}Ge{sub 2} and CeAuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2} (x=0.4) appear to be in a mixed +3/+4 valence state; DyAuAl{sub 4}Ge{sub 2} undergoes an antiferromagnetic transition at 11K and below this temperature exhibits metamagnetic behavior. The Eu atoms in EuAuAl{sub 4}(Au{sub x}Ge{sub 1-x}){sub 2} (x=0.4) appear to be in a 2+ oxidation state.

OSTI ID:
20784755
Journal Information:
Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 11 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English