Magnetic properties of nanoscale Sm0.25Zr0.75Fe3 produced by mechanical alloying

Mechanical alloying of Sm, Zr, and Fe with the composition of Sm0.25Zr0.75Fe3 was studied as a function of milling time up to 20 h using X-ray diffraction (XRD), Moessbauer spectroscopy, and magnetometry. In XRD, initial crystalline Bragg reflections due to Sm, Zr, and Fe changed to a single broad maximum after 20 h milling, and in Moessbauer spectroscopy, the initial sextet changed to a broad singlet. These results and the temperature and magnetic-field dependent studies of the 20 h milled sample showed the material to be a superparamagnet with considerable mechanical strains and a wide particle-size distribution with average particle size of about 33 A and blocking temperature of about 220 K. Comparison of these results with those in mechanically alloyed SmFe3 shows that Zr accelerates the rate of mechanical synthesis. (orig.)