MAGNETIC-PROPERTIES OF NANOSCALE SM0.25ZR0.75FE3 PRODUCED BY MECHANICAL ALLOYING

Mechanical alloying of Sm, Zr, and Fe with the composition of Sm0.25Zr 0.75Fe3 was studied as a function of milling time up to 20 h using X-r ay diffraction (XRD), Mossbauer 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 Mossbauer spectro scopy, the initial sextet changed to a broad singlet. These results an d the temperature and magnetic-held dependent studies of the 20 h mill ed sample showed the material to be a superparamagnet with considerabl e mechanical strains and a wide particle-size distribution with averag e particle size of about 33 Angstrom 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. (C) 1998 Elsevier Science B.V. All rights reserved.