NEUTRON-DIFFRACTION STUDIES OF NDNFEM-X-YVXALY [(N,M)=(1,12), (2,17),(3,29)]

Several NdnFem-x-yVxAly [(n,m)=(1,12), (2,17), (3,29)] samples were pr epared and analyzed using neutron powder diffraction. Rietveld analysi s of the neutron diffraction data indicates that the V and Al substitu ents take those sites with similar environments in all three phases, a s observed in our previous study of Ti-substituted compounds. It was c onfirmed that the diffraction data of the 3:29 compound can be better refined using the A2/m space group than using the P2(1)/c space group. The SQUID measurements show that all samples have Curie temperatures well above room temperature. The neutron diffraction results show that the easy direction is along the a axis for the 3:29 compounds, along the c axis for the 1:12 compounds and in the a-b plane for 2:17 compou nds, respectively. The average site magnetic moments, the metal-metal bond lengths acid the unit cell parameters of these compounds are comp ared with those of the Ti-substituted compounds. (C) 1996 American Ins titute of Physics.