Rare Earth Iron Intermetallic Compounds Of Er <sub> 2 </ Sub> Of Fe <sub> Of Al <sub> X 17-x </ Sub> </ Sub> And Er <sub> 2 </ Sub> Fe <sub> 17 -x </ Sub> Mn <sub> X </ Sub> C Structu

The crystallographic structure and magnetic properties of 2;17-type rare-earth iron intermetallic compounds Er2Fei7_xAlx and Er2Fei7.xMnxC have been studied in detail by means of neutron diffraction X-ray diffraction and magnetic measurement in this dissertation. By studying the change of structure and magnetic properties with increasing Al> Mn content, we explored the relation between crystallographic structure and magnetic properties.In the Er2Fei7.xAlx compounds, Al atoms only occupy 18f and 18h sites for Th2Zni7-type structure (or 12j and 12k sites for Th2Nii7-type structure) when Al content is small(x < 2), and avoid 6^ 9d sites. With increasing Al content (x > 2), Al atoms still completely avoid 9d site, but preferentially occupy 6c and 18f sites while the occupancy factor of 18h sites increases slowly. In compounds, the moments of Er sublattice are ferrimagnetically coupled to that of the Fe sublattice; the Curie temperature Tc of Er2Fei7.xAlx increases at first with increasing Al content x, reaches a maximum near x=3, then decreases; saturated magnetization reduces linearly with increasing Al content. All of these magnetic properties may be explained by exchanged coupling^ magnetic dilution and molecular field model.In Er2Fei7.xMnxC series, all of compounds have Th2Nii7-type hexagonal structure. The neutron diffraction data of Er2FeI5Mn2C have been refined by Rietveld analysis program, the refined results indicated that: Fe atoms on 12k> I2j^ 6g and 4f sites are substituted partly by Mn atoms, and the occupancy factor of 4f dumb-bell sites is the largest one. All of the moments lie in the plane perpendicular to the six-fold axis and exhibit planar magnetic anisotropy at room temperature, and the moment direction of Er sublattice is opposite to that of Fe sublattice. The difference of Al and Mn substitution was discussed.