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

Abstract

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 (4πI_s=2360–12 300 G) and the crystalline anisotropies (H_A=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 GdCo_5IH_c 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 _BH_c is 5200 Oe.