NUCLEAR-MAGNETIC-RESONANCE STUDY OF THE ND(2)CO(17)A(X)(A=N,H) COMPOUNDS

The Nd-145, Nd-143, and Co-59 nuclear magnetic resonance (NMR) spin-ec ho spectra and echo decays for Nd2Co17 and its interstitial nitride, N d2Co17N3 and hydride Nd2Co17H3.6 at 4;2 and 77 K at zero field and in applied fields of up to 5 T are reported. The Nd quadrupole splitting of 3.88 MHz for Nd-145 in Nd2Co17 is reduced to 0.37 MHz for Nd2Co17N3 . The value for Nd2Co17H3.6 is 3.66 MHz. The reduction of quadrupole s plitting for Nd2Co17N3 as compared to the host Nd2Co17 is 50% larger t han for the isostructural Nd2Fe17N3 and is assigned to a huge increase in the magnitude of the lattice electric field gradient at the Nd sit e and, thus to a huge rise of magnetocrystalline anisotropy caused by neighboring N atoms, whereas H atoms have only a slight influence on b oth quantities. The Co-59 spectrum of the nitride is much different fr om that of the host compound indicating a large influence of N neighbo rs on Co hyperfine fields, whereas only minor changes are observed aft er hydriding. (C) 1997 American Institute of Physics.