NEUTRON-DIFFRACTION STRUCTURAL STUDY OF CE2FE17-XGAX

Six samples of Ce2Fe17-xGax with nominal Ga content x equal to 0, 0.3, 0.5, 0.7, 1.0, 2.0 have been studied by powder neutron diffraction at room temperature. Both crystalline and magnetic refinements have been carried out. All six samples adopt the Tn(2)Zn(17)-type rhombohedral structure. The only additional phase found is alpha-iron. Gallium atom s are found to have high affinity for the iron 18h site, and are absen t from the 9d and 18f sites. The Ga substitution for Fe leads to an ex pansion of both the a and c axes. The Curie temperature increases from 238 K for Ce2Fe17 to 406 K for Ce2Fe15Ga2. Magnetic refinements on th e samples with x=0.3, 0.5, 0.7, 1.0, and 2.0 reveal that the magnetic moments of the four Fe sites are in the basal plane and that their val ues increase with increasing Ga content. (C) 1996 American Institute o f Physics.