Magnetic properties of R2Co17-xGax compounds (R=Sm and Gd)

The magnetic properties of R2Co17-xGax compounds with 0 less than or equal to x less than or equal to 5 for R=Gd and 0 less than or equal to x less than or equal to 7 for R=Sm were studied by means of magnetic measurements and X-ray diffraction on magnetically aligned powders. The measurements have shown that increasing Ga concentration leads to a sign reversal of the magnetocrystalline Co-sublattice anisotropy from easy-plane anisotropy for low Ga concentration to easy-axis anisotropy for higher Ga concentration. In the Sm2Co17-xGax compounds, the Sm-sublattice anisotropy and the Co-sublattice anisotropy add constructively. This leads to materials of considerable magnetic hardness and the occurrence of narrow domain walls, in particular at relatively high Ga concentrations. There is a strong decrease of the Curie temperature with Ga concentration in both series. (C) 1997 Elsevier Science S.A.