Phase stability and site preference of Sm(Fe,T)(12)

The structure of intermetallics Sm(Fe,T)(12) is analyzed via a quasi-ab ini tio pair potentials Phi (Fe-Fe)(r), Phi (Sm-Fe)(r), Phi (Sm-Sm)(r), Phi (Sm -T)(r), Phi (Fe-T)(r) and Phi (T-T)(r). The calculation results show that e ach of Cr, V, Mo and Ti significantly decreases the cohesive energy of Sm(F e,T)(12), and thus stabilizes its structure of ThMn12. The calculated latti ce constants coincide quite well with experimental values. The sequence of site preference occupation is 8i, 8j and 8f, with the 8i occupation corresp onding to the greatest energy decrease. The calculated results also show th at each of Co, Cu, Ni and Sc does not stabilize the system with the structu re of ThMn12. The calculated crystal structure can recover after either an overall wide-range macro-deformation or atomic random motion, demonstrating that an Sm-Fe-T system has the stable structure of ThMn12. The crystal spa ce group remaining consistent at different temperatures is also shown in th is paper. All of the results verify that the first principle potentials bas ed on the lattice inversion technique are effective. (C) 2001 Elsevier Scie nce B.V. All rights reserved.