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Author Girt, E. ♦ Altounian, Z. ♦ Swainson, I. P. ♦ Krishnan, K. M. ♦ Thomas, G.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ FERROMAGNETIC MATERIALS ♦ NEODYMIUM ALLOYS ♦ IRON ALLOYS ♦ GALLIUM ALLOYS ♦ THERMAL EXPANSION ♦ NEUTRON DIFFRACTION ♦ MAGNETIC MOMENTS ♦ CRYSTAL STRUCTURE ♦ TEMPERATURE DEPENDENCE
Abstract In Nd{sub 2}Fe{sub 17{minus}{delta}}Ga{sub {delta}} ({delta}=0;0.5;1;1.5;2), Ga substitutes for Fe without changing the crystal structure. Neutron diffraction measurements show that Ga preferentially substitutes for Fe in the 18h sites only. The magnetic moments in Nd{sub 2}Fe{sub 17{minus}{delta}}Ga{sub {delta}}, below the Curie temperature, T{sub c}, are found to be in the basal plane. Below T{sub c} the unit cell constant, {ital c}, decreases with increasing temperature for Nd{sub 2}Fe{sub 17{minus}{delta}}Ga{sub {delta}} ({delta}{le}1). For Nd{sub 2}Fe{sub 17{minus}{delta}}Ga{sub {delta}} ({delta}{gt}1), the thermal expansion coefficient changes sign and becomes positive for Nd{sub 2}Fe{sub 15}Ga{sub 2}. The relative decrease in the Fe(6c){endash}Fe(6c) distance is twice as large as the decrease in the {ital c} axis below T{sub c}. Below T{sub c}, the Fe(6c){endash}Fe(6c) distance decreases with an increase in the Ga concentration, while above T{sub c} the Fe(6c){endash}Fe(6c) distances are found to be independent on Ga concentration indicating that the presence of Ga decreases the negative exchange coupling between Fe atoms. {copyright} {ital 1999 American Institute of Physics.}
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1999-04-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 85
Issue Number 8


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