Anomalous thermal expansion in substituted Nd{sub 2}Fe{sub 17{minus}x}Si{sub x} and Nd{sub 2}Fe{sub 17{minus}x}Al{sub x} compounds

Journal Article · Wed Nov 01 04:00:00 EST 1995 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/20.489602· OSTI ID:186940

Zhang, X D; Shumsky, M G; James, W J ^[1]; Yelon, W B ^[2]

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1. Univ. of Missouri, Rolla, MO (United States). Graduate Center for Materials Research
2. Univ. of Missouri, Columbia, MO (United States). Research Reactor Center

The temperature dependencies of the lattice parameters were measured from room temperature to 400 C for powders of the substituted compounds Nd{sub 2}Fe{sub 17{minus}x}Al{sub x} and Nd{sub 2}Fe{sub 17{minus}x}Si{sub x}, x = 0,1,2,3, using high-temperature x-ray diffraction. All compounds crystallize in the rhombohedral Th{sub 2}Zn{sub 17}-type structure (space group R{bar 3}m). Invar-type anomalies are found in the temperature dependence of a and c below the Curie temperatures, {Tc}, but featuring different substitution effects of Fe by Al and Si atoms, respectively. The Nd{sub 2}Fe{sub 17{minus}x}Al{sub x} and Nd{sub 2}Fe{sub 17{minus}x}Si{sub x} compounds retain easy-plane anisotropies upon substitution up to x = 3. Therefore, the observed spontaneous volume magnetostrictions are due mainly to the isotropic exchange contribution of the iron sublattice. According to the localized model of exchange interactions in R-Fe compounds, the different substitution effects can be ascribed to the different preferential occupation tendencies of Al and Si atoms on the sites of the Th{sub 2}Zn{sub 17}-type structure.

• OSTI ID: 186940
• Report Number(s): CONF-950404--
• Journal Information: IEEE Transactions on Magnetics, Journal Name: IEEE Transactions on Magnetics Journal Issue: 6Pt2 Vol. 31; ISSN IEMGAQ; ISSN 0018-9464
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
IRON BASE ALLOYS
LATTICE PARAMETERS
NEODYMIUM ALLOYS
PERMANENT MAGNETS
SILICON ALLOYS
THERMAL EXPANSION