1.2 Neutron diffraction study on the crystal and magnetic structures of are-melted PrFe_10.5Mo_1.1C_0.4 alloy

摘要

The crstal and magnetic structures, expecially the site occupation of C atoms in the crystal cell of arc-melted PrFe_10.5Mo_1.1C_0.4 permanent magnetic alloy have been determined by means of powder neutron diffraction study. Reitveld analysis of the neutron diffraction data indicates that Mo atoms prefers the 8i site, about 76 percent of the C atoms occupy the 8i substitution site, and the other part of Catoms enter the 2b interstitial site. The exact molecular formula should be Pr(Fe_10.575Mo_1.250C_0.175)C_0.055. It seems that the site occupation of C atoms in the ThMn_12-type carbides depends not only on the kind of substitution metals, but also on the components of the substitutional transition metals in the compounds. There are still amount of work to make systematic studies on the relations between them. The effect of Catoms on the magnetic properties is also discussed.