Atomistic investigation on site preference and lattice vibrations of Sm(Co,M)12 (M = Cr, Ti, V, Nb, Fe)

The phase stability and site preference of the intermetallics Sm(Co,M)12 (M = Cr, Ti, V, Nb, Fe) are evaluated by using interatomic pair potentials based on Chen's lattice inversion method. The calculated results show that substituting either Cr, Ti, V, Nb or Fe atoms makes the crystal cohesive energy of Sm(Co,M)12 decrease markedly, proving that these atoms can stabilize Sm(Co,M)12 with ThMn12 structure. The calculated lattice constants coincide quite well with the experimental data. The order of site preference of these ternary elements T is 8i, 8j and 8f with the occupation of 8i corresponding to the greatest energy decreases. The properties related to lattice vibration, such as the phonon densities of states, specific heat and vibrational entropy, are also evaluated