Abstract
The Sm-Co permanent magnets have received intensive interests in the electromechanical and micro-electromechanical industry due to the high energy product and the high Curie temperature. The magnetocrystalline anisotropy affects the coercivity thus influences the energy product. Hence the magnetocrystalline anisotropy constant is an important parameter in practical utility. The anisotropy field (Ha) was determined by measuring the easy and hard axis magnetization on powder aligned in a field and fixed in epoxy. But it is difficult to get the powder of single domain and the metastable materials decompose during the powdering process. As a result, simulation is a good method to obtain the magnetocrystalline anisotropy constant. SmCo5, SmCo7, SmCo6.7Zr0.3 and SmCo6.7V0.3 are discussed in this study. TEM and X-ray diffraction are used to analysis the microstructure. First-principles density functional calculation is used for discussing the influence of atomic environment on microstructure, magnetization, and magnetocrystalline anisotropy. The total energy calculations show the third element doping (Zr or V) can stabilize the TbCu7 structure. The Zr or V atoms replace the 2e Co atoms. The calculated magnetic moment agreed with experiments within 6% difference. The calculated magnetocrystalline anisotropy constants are about 3~4 times smaller than the measured value. The trends are anisotropy (SmCo5) > anisotropy (SmCo7), anisotropy (SmCo6.7Zr0.3) > anisotropy (SmCo7), anisotropy (SmCo6.7V0.3) > anisotropy (SmCo7) which can be explained by the symmetry of atoms.