Structure and magnetic properties of rare-earth chromium germanides RECr{sub x}Ge{sub 2} (RE=Sm, Gd-Er)
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada)
The ternary rare-earth chromium germanides RECr{sub x}Ge{sub 2} (RE=Sm, Gd-Er) have been obtained by reactions of the elements, either in the presence of tin or indium flux, or through arc-melting followed by annealing at 800 deg. C. The homogeneity range is limited to 0.25{<=}x{<=}0.50 for DyCr{sub x}Ge{sub 2}. Single-crystal and powder X-ray diffraction studies on the RECr{sub 0.3}Ge{sub 2} members revealed that they adopt the CeNiSi{sub 2}-type structure (space group Cmcm, Z=4, a=4.1939(5)-4.016(2) A, b=16.291(2)-15.6579(6) A, c=4.0598(5)-3.9876(2) A in the progression for RE=Sm to Er), which can be considered to be built up by stuffing transition-metal atoms into the square pyramidal sites of a 'REGe{sub 2}' host with the ZrSi{sub 2}-type structure. (The existence of YbCr{sub 0.3}Ge{sub 2} is also implicated.) Only the average structure was determined here, because unusually short Cr-Ge distances imply the development of a superstructure involving distortions of the square Ge net. Magnetic measurements on RECr{sub 0.3}Ge{sub 2} (RE=Gd-Er) indicated that antiferromagnetic ordering sets in below T{sub N} (ranging from 3 to 17 K), with additional transitions observed at lower temperatures for the Tb and Dy members. - Graphical abstract: The average structure of RECr{sub x}Ge{sub 2} corresponds to the CeNiSi{sub 2}-type, with Cr atoms entering square pyramidal sites. The Cr atoms provide no contribution to the effective magnetic moment in these compounds, which undergo antiferromagnetic ordering below 20 K.
- OSTI ID:
- 21212166
- Journal Information:
- Journal of Solid State Chemistry, Vol. 182, Issue 1; Other Information: DOI: 10.1016/j.jssc.2008.10.013; PII: S0022-4596(08)00533-1; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANNEALING
ANTIFERROMAGNETISM
CHROMIUM COMPOUNDS
DYSPROSIUM COMPOUNDS
ERBIUM COMPOUNDS
GADOLINIUM COMPOUNDS
GERMANIDES
HOLMIUM COMPOUNDS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MELTING
MONOCRYSTALS
ORTHORHOMBIC LATTICES
SAMARIUM COMPOUNDS
SPACE GROUPS
TEMPERATURE RANGE 1000-4000 K
TERBIUM COMPOUNDS
TIN
X-RAY DIFFRACTION
ZIRCONIUM SILICIDES