Atomistic study on the site preference and lattice vibration of Gd_3−xY_xCo₂₉T₄B₁₀ (T=Al and Ge)

The effects of the Y substitution for Gd on the structural stability and the site preference of intermetallics Gd_3−xY_xCo₂₉T₄B₁₀ (T=Al and Ge) are studied by using a series of interatomic pair potentials. The calculated results show Y can stabilize Gd_3−xY_xCo₂₉T₄B₁₀ with the tetragonal structure, and Y substitute for Gd with a strong preference for the 2b sites. The calculated lattice parameters are in good agreement with the experimental data. Furthermore, the total and partial phonon densities of states are evaluated for the Gd_3−xY_xCo₂₉T₄B₁₀ compounds with the tetragonal structure. 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. - Graphical abstract: The lattice cell of Gd₃Co₂₉T₄B₁₀ consists of 92 atoms, or two Gd₃Co₂₉T₄B₁₀ formula units, with fourteen distinct kinds of site. Rare-earth atoms occupy 2b and 4d sites, Co atoms occupy the Co1(2c), Co2(8i1), Co3(8i2), Co4(8i3), Co5(8j1), Co6(8j2) and Co7(16k), T atoms occupy the T(8i) sites, and B atoms occupy the B1(2c1), B2(2c2), B3(8i) and B4(8j) sites. - Highlights: • The application of the pair potentials obtained from lattice-inversion method. • The lattice vibrations for Gd_3−xY_xCo₂₉T₄B₁₀ (T=Ge and Al) are first evaluated. • The Y atoms should prefer the 2b site of Gd_3−xY_xCo₂₉T₄B₁₀ compounds. • The total and partial phonon densities of states are evaluated for the Gd_3−xY_xCo₂₉T₄B₁₀ compounds with the tetragonal structure. • A qualitative analysis is carried out with the relevant potentials for the vibrational modes