Magnetic properties of YCo5 (70%wt)+Y2Co17 (30%wt) nanocomposite powders at low temperatures

Nanostructured YCo5 (70%wt)+Y2Co17 (30%wt) composite powders were prepared by mechanical milling and subsequent annealing at 1073 K for 1.5 min. The average grain size D of the YCo5 and Y2Co17 phases, obtained from XRD data, was 14 and 12 nm, respectively. The temperature dependence of the magnetic properties was studied by DC magnetization measurements at temperatures T ranging from 3 to 300 K. Hysteresis loops (Hmax=70 kOe) show that both the coercivity HC and the squareness sigmar/sigmamax are temperature-dependent. The coercivity increases from 12 kOe at room temperature to 18 kOe at T=3 K. The observed enhanced remanence (sigmar/sigmamax > 0.5) indicates that a strong exchange coupling is present at all temperatures used in this study. The maximum magnetization sigmamax changes little with temperature and has a value of about 70% of the effective saturation magnetization of the title compound.