Annealing Effect on Microstructure and Coercivity of YCo5 Nanoparticles Obtained by Mechanical Milling
Nanocrystalline YCo5 powders with high coercivity were prepared by mechanical milling and subsequent heat treatment at 820 °C for different annealing times, ta = 2.5, 3.0, 3.5 and 4.5 min, obtaining average crystallite sizes of 17, 19, 32 and 39 nm., respectively. The coercivity values were determined from the hysteresis loops measured at maxima fields of Hm = 5 and 20 T. The highest coercivity was obtained for the sample exhibiting 19 nm, where at room temperature and Hm = 5 T, the coercivity value is of 9.0 kOe. At 77 K and Hm = 5 T, the coercivity increase to 11.8 kOe and for Hm = 20 T, a higher value such as 13.1 kOe was found. The Ms/Mr ratio is enhanced to 0.62 indicating the occurrence of exchange interaction among nanocrystalline magnets.
J. T. Elizalde Galindo, R. Sato Turtelli, R. Grössinger, J. A. Matutes-Aquino, "Annealing Effect on Microstructure and Coercivity of YCo5 Nanoparticles Obtained by Mechanical Milling", Advanced Materials Research, Vol. 68, pp. 122-126, 2009