Rare-earth transition metal carbides

Methane and ethane were used to prepare rare-earth transition metal carbides. The structural and magnetic properties of these carbides have been studied. Interstitial carbon atoms expand the unit cell of the R/sub 2/Fe/sub 17/ (R=Y, Ce, Pr, Nd, Sm, Dy, Er) and RFe/sub 10/M/sub 2/ (R=Y, Nd, Sm and M=Mo, V) structures by about 7.5 and 1.5%, respectively. Thus lattice expansion resulted in increases of Curie temperature and spontaneous magnetization. The easy magnetization direction of Sm/sub 2/Fe/sub 17/ is changed from planar to uniaxial with the carbon uptake, while in other R/sub 2/Fe/sub 17/ compounds it remains planar. For RFe/sub 10/M/sub 2/ with R=Y and Nd, a uniaxial anisotropy is observed after carbonation.<
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