Atomistic Simulation of Permanent Magnets With Reduced Rare-Earth Content

The goal of ‘Perfekt’, a publicly funded joint project with several partners from science and industry, is to detect, characterize and industrialize new (multi-component) permanent magnetic phases that can be used for energy converters in a cost efficient way. The desired compositions contain no, or at least a drastically reduced (70%) content of, rare earth metals so that the economical as well as technological dependence on expensive rare earth elements can be decreased. The potential energy densities of the anticipated new materials should ideally be as high as those of state of the art magnets, (BH)max > 350 kJ/ $$\mathrm {m}^3$$ m 3 . However, materials that can close the gap between ferrites and Fe-Nd-B on the energy density-cost-landscape (saturation polarization > 1 T, anisotropy constant > 1 MJ/ $$\mathrm {m}^3$$ m 3 ) are also desirable for applications such as smaller engines and sensors. The experimental works on the assessment of new high potential phases should be guided by simulative studies, for which ab-initio methods using density functional theory were used. The associated research focused on the determination of the thermodynamic stabilities of relevant structures at 0 K and for the most promising phases, temperature dependencies were analyzed taking into account phonon contributions to the free energy. In addition to determining the saturation magnetization, the anisotropy constants of these phases were calculated, enabling an assessment of their permanent magnetic qualities. Within the reporting period and scope of ’SimMag’, we investigated three compounds that have been experimentally predicted as promising. These include one rare-earth-free compound, (Fe,Mn) $$_2$$ 2 (P,Si), and two rare-earth containing phases, (Y,Sm)(Fe,Ti) $$_{12}$$ 12 and Y(Fe,V) $$_{12}$$ 12 . The derived results will be presented in the following.