Atomistic simulation for disordered TbCu_7-type compounds SmCo_7 and Sm(Co,T)_7 (T = Ti, Ga, Si, Cu, Hf, Zr)

摘要

The computational evolution from ordered SmCo_5 (CaCu_5-type) compound to disordered SmCo_7 (TbCu_7-type) compound has been implemented in this work. Based on statistical simulation, both the phase stabilities and the lattice constants of the calculated SmCo_7 series are in good agreement with experiments and a sort of 3g layer twisting deformation is observed. The calculated site preferences and lattice constants of the disordered ternary SmC0_(7-X)T_x (T = Ti, Ga, Si, Cu, Hf, Zr) are also in consonance with experimental data. SmCo7's natural structure selection has also been investigated and understood on the basis of phase stability and cohesive energy. This work lays a foundation for further first principles studies on the magnetic properties of disordered TbCu7-type high-temperature permanent magnets.