Atomistic simulation for disordered TbCu7-type compounds SmCo7 and Sm(Co,T)7 (T = Ti, Ga, Si, Cu, Hf, Zr)

The computational evolution from ordered SmCo5 (CaCu5-type) compound to disordered SmCo7 (TbCu7-type) compound has been implemented in this work. Based on statistical simulation, both the phase stabilities and the lattice constants of the calculated SmCo7 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 SmCo7−xTx (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.

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