A NEW PHASE IN THE ND-FE SYSTEM - CRYSTAL-STRUCTURE OF ND5FE17

A new stable phase in the NdFe system has been identified. X-ray diffraction examination of single crystals was used to establish the crystal structure of Nd5Fe17. The hexagonal space group is P63 mcm and the lattice parameters are a = 2.0214(8) nm, c = 1.2329(8) nm, Z = 12. The Nd5Fe17 structure is built up of layers which are a tessellation of triangles, pentagons, hexagons and heptagons. The stacking of layers forms antiprisms. Clusters of neodymium atoms only are made of trigonal antiprisms or regular octahedra stacked upon each other to form infinite columns. Each neodymium cluster is surrounded by a first ring of nine pentagonal antiprisms centred by iron atoms and a second ring of 12 antiprisms with hexagonal and heptagonal faces centred by neodymium atoms. © 1990.