ND-145 NMR-STUDY OF NDXY2-XCO17 AND NDXY2-XCO14B

The Nd-145 Nuclear magnetic resonance (NMR) spin-echo spectra of the N dxY2-xCo17 and NdxY2-xCo14B compounds at 4.2K are presented. Quadrupol e septets are assigned to the Nd sites 4f, 3g in NdxY2-xCo14B and 69 i n NdxY2-xCo17. A large change of the quadrupole splitting between x=0. 1 and x=0.2 and only slight changes of the hyperfine fields is observe d in Nd2Y2-xCo14B. The effect is attributed to a change of the easy ma gnetisation direction with Nd content from the c-plane to the c-axis. For NdxY2-xCo17 slight changes of quadrupole splitting and hyperfine f ield in the whole concentration region 0.1<x<2.0 are observed only, re flecting a planar anisotropy of the compounds in the whole series. Fro m the quadrupole splittings the values of the 4f-electron- and the lat tice contributions to the electric field gradient at Nd nuclei are der ived. The lattice contributions are related to the crystal electric fi eld coefficient A(2)(0) at the neodymium sites. The A(2)(0) values amo unt to 192 Ka(0)(-2) for the 4g and 57 Ka(0)(-2) for the 4f site in Nd xY2-xCo14B. The directions of magnetic moments at the Nd sites are als o obtained. (C) 1997 Elsevier Science S.A.