Structural stability, site preference and lattice vibrations of RFe 12− xTa x (R = Tb, Dy, Ho)

Abstract

An investigation of the structural and vibrational properties of RFe 12− x Ta x (R = Tb, Dy, Ho) compounds has been performed by a series of interatomic pair potentials obtained through the lattice inversion method. Calculated results show Ta atoms can stabilize RFe 12− x Ta x with ThMn 12-type structure, and Ta atoms substitute for Fe with a strong preference for the 8 i sites. The phase stability of the intermetallics RFe 12− x Ta x is tested by many means including random atom shift, global deformation and high temperature disturbance under the control of the pair potentials. The calculated lattice parameters are corresponding to the experimental results. In particular, the phonon densities of states for RFe 11.5Ta 0.5 are first evaluated. A qualitative analysis is carried out with the relevant potentials for the vibrational modes, which makes it possible to predict some properties related to lattice vibration.