Hard magnetic properties of isotropic nanostructured Y0.5Pr0.5Co5 powders

The hysteresis loops and recoil demagnetization curves of single-phase nanostructured Y0.5Pr0.5Co5 powders, produced by high-energy mechanical milling, have been measured in the temperature range from 8 to 300K. The temperature dependence of hard magnetic properties is reported. TEM studies reveal that a nanostructure with an average grain size of about 9.2nm is developed in the powder particles. Powders show room temperature intrinsic coercivity of 13.6kOe, reduced remanence of 0.68 and medium-strength permanent magnet properties: Br=6.95kG, BHC=5.78kOe and (BH)max=10.2MGOe. The shape of the virgin magnetization curve and the dependence of iHC on the maximum applied field suggest that the coercivity mechanism is mainly controlled by pinning. Intergrain exchange coupling was evidenced by remanence enhancement. δM plot determined at room temperature indicates the existence of positive interactions of exchange type. A noticeable increase in the irreversible susceptibility and reduced remanence has been found to occur below 100K