Structural and Magnetic properties of nanocrystalline Pr2Co7Cx and Pr2Co7Hy alloys

We study the influence of the insertion of a light element, suchas carbon or hydrogen, on the structural and magnetic properties of the Pr(2)Co(7)compounds. The characterizations were performed by powder X-ray diffraction, transmissionelectron microscopy and thermomagnetic measurements. The X-ray diffraction of these alloys has shown that the Pr2Co7Cx and Pr2Co7Hy phases adopt a hexagonal type Ce2Ni7 type structure. The Rietveld analysis points out a lattice expansion after carbon insertion. Moreover, we have shown that the insertion of carbon or hydrogen is an effective way to increase the Curie temperature without changing the nature of the ferromagnetic transition. This could be due to the strengthening of exchange interactions. Important modifications of the anisotropy and coercivity of the compounds are observed to depend on the nature of the inserted element.