Structural and magnetic properties of RFe4P12 (R=Pr, Nd) studied by neutron diffraction

In this work we present a neutron powder diffraction study of the ternary r are-earth phosphides PrFe4P12 and NdFe4P12. High-resolution measurements of the structural temperature dependence reveal large-amplitude thermal vibra tions of the rare-earth ions, consistent with speculations that the ion is weakly bound in an oversized atomic 'cage' formed in the skutterudite cryst al structure. In addition, low temperature neutron diffraction measurements of RFe4P12 (R=Pr, Nd) were performed. Whereas the proposed long-range anti ferromagnetic ordering in PrFe4P12 could not be confirmed, NdFe4P12 orders ferromagnetically below T-C = 1.94 K with an ordered magnetic Nd3+ moment o f 1.61(7) mu (B) at 1.5 K. (C) 2001 Elsevier Science B.V. All rights reserv ed.