Disordered structure with CaCu5 type and uniaxial magneto-crystalline anisotropy induced by the high-entropy cocktail effect in Sm2Co17-based intermetallics
*a
Linhan
Yin
a
Abstract
A series of Sm2Co17-based high-entropy intermetallic compounds with a structural formula of (Sm1/n⋯Rn1/n)2(Fe1/3Co1/3Ni1/3)17 (R = Y, La, Ce, Pr, or Nd) were designed using random occupancies of equiatomic ratios of light rare earths at the Sm site and 3d transition metals at the Co site. These high-entropy samples were theoretically and experimentally verified to be single-phase using the thermodynamic theory of high entropy (ΔS > 20.06R) and powder X-ray diffraction, respectively. Based on Rietveld structural refinement, the preferred structural model is found to be a disordered hexagonal CaCu5-type structure, where the rare earths and 3d transition metals randomly co-occupy the 1a site. The high-entropy cocktail effect not only causes uniaxial anisotropy, but also modulates saturation moment (Ms) and anisotropy field (HA). The contribution to the magnetic moment of the valence state for Ce is studied using a magnetic valence model.
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