Effect of $R$-site substitution and the pressure on stability of $R$Fe${}_{12}$: A first-principles study

Abstract

We theoretically study the structural stability of $R$Fe${}_{12}$ with the ThMn${}_{12}$ structure ($R$: rare-earth elements, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, Lu, Y, or Sc, or group-IV elements, Zr or Hf) based on density functional theory. The formation energy has a strong correlation with the atomic radius of $R$. The formation energy relative to simple substances decreases as the atomic radius decreases, except for $R=$ Sc and Hf, while that relative to $R_2$Fe${}_{17}$ and bcc Fe has a minimum for $R=$ Dy. The present results are consistent with recent experimental reports in which the partial substitution of Zr at $R$ sites stabilizes $R$Fe${}_{12}$-type compounds with $R=$ Nd or Sm. Our results also suggest that the partial substitution of Y, Dy, Ho, Er, or Tm for Nd or Sm is a possible way to enhance the stability of the ThMn${}_{12}$ structure. Under hydrostatic pressure, the formation enthalpy decreases up to $\approx$ 6 GPa and then starts to increase at higher pressures.

6 pages, 6 figures

References in corpus (4)

• Quantum Theory of Rare-Earth Magnets
• First-principles study on stability and magnetism of NdFe11M and NdFe11MN for M=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn
• Role of typical elements in Nd${}_2$Fe${}_{14}$$X$ ($X$ = B, C, N, O, F)
• First-principles study of intersite magnetic couplings in NdFe${}_{12}$ and NdFe${}_{12}$X (X = B, C, N, O, F)

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