EFFECTS OF P DOPING IN ND2FE17 AND PHASE-DIAGRAM OF FE RICH ND-FE-P

It was found that a P-doping process occurs in Nd2Fe17 by gas phase re action around 673 K. A decrease of the lattice constants a and c by up to approximate to 0.6 and approximate to 0.8%, respectively, and an i ncrease of the Curie temperature by up to approximate to 30 K were obs erved. The P-doped 2:17 phase dissolves around 763 K. Four phase regio ns in the phase diagram of Fe rich Nd-Fe-P alloys below 1223 K were de termined. The phases in each region are: A: Nd2Fe17 + alpha-Fe+NdP; B: alpha-Fe + NdP + Nd2Fe12P7; C: alpha-Fe + Nd2Fe12P7 + Fe3P; D: Nd2Fe1 2P7 + Fe2P + Fe3P. The variation of the lattice constants with composi tion of the alloys is as large as (Delta a/a)(max) approximate to 0.8% for NdP and (Delta a/a)(max) approximate to 1.2% and (Delta c/c)(max) approximate to 0.8% for Nd2Fe12P7 suggesting a certain soluble range for the compounds.