NUCLEAR-MAGNETIC-RESONANCE STUDY OF THE SM2FE17 CARBIDES

The Sm-147 and Sm-149 NMR spin echo spectra and the spin echo decays o f Sm2Fe17Cx for x = 0, 0.5, 1 and about 3 at 4.2 K are reported, The q uadrupole septets in the spectra are assigned to the samarium 6c site with different numbers of carbon atoms occupying the neighbouring 9e i nterstitial sites, A significant influence of carbon neighbours on the Sm quadrupole splitting and hyperfine field is observed and is attrib uted to a strong change of the Sm valence electron distribution and po larisation caused by carbon neighbours. From the quadrupole splittings the values of the lattice electric field gradient and the correspondi ng crystal electric field coefficient A(2)(0) are derived. For the Sm sites with 0 (3) carbon nearest neighbours the A(2)(0) value of -66 Ka (0)(-)2 (-350 Ka(0)(-2)) is obtained.