Prediction of the site occupations of the ThMn 12-type intermetallics YFe 12− xMo x by combining thermodynamic model with ab-initio calculations

Abstract

Site occupations of atoms on sublattices of ThMn 12-type intermetallics YFe 12− x Mo x with different composition and temperature are predicted by combining the thermodynamic sublattice model with ab-initio energetic calculations on end-members. The results show that the ordering tendencies of different types of elements are mostly unvaried with respect to temperature. The 2 a sublattice is occupied by the Y atoms exclusively, and the 8 f and 8 j sublattices are both occupied by the Fe atoms with nearly 100%, while the 8 i sublattice is shared by Mo and Fe atoms. The predicted site occupancy fractions agree well with the available experimental data. For the nonstoichiometric compound YFe 12− x Mo x , the site occupation of the Mo atoms in the 8 i sublattice increases with Mo content when x ≤ 4. It is near 100% when x = 4. When x > 4, the Mo atoms also tend to occupy the 8 j sublattice. The approach employed in the present paper is expected to be generalized to other complicated structures, once their crystallographic information is available.