Magnetic and Crystallographic Properties of Some Rare Earth Cobalt Compounds with CaZn5 Structure

The magnetic and crystallographic properties of CaZn5-type intermetallic compounds of cobalt and rare-earth elements (including Th) have been investigated. Strong deviations from 1:5 stoichiometry are observed when the rare-earth radius becomes relatively small. Both the saturation magnetizations (4πIs=2360–12 300 G) and the crystalline anisotropies (HA=25–210 kOe) depend on the rare-earth component. The coercive forces have been studied as a function of the milling time. For SmCo5 and GdCo5IHc values larger than 13 000 Oe are observed. These high values are possibly due to small structural details in SmCo5 and GdCo5, if compared to the other compounds. First experiments for making permanent magnets by pressing fine powders of SmCo5 in a magnetic field have led to an energy product of 8.1×106 G Oe; the corresponding value for BHc is 5200 Oe.