Structural Modulation in B8 1 ‐B8 2 ‐Type Ni 1+ δ (In/Sn) ( δ = 0.2–0.5)

In the present work, the effect of indium substitution for tin in the ternary Ni 1+ δ (In/Sn) ( δ = 0.2–0.5) (Ni 2 In(B8 2 )/NiAs(B8 1 )‐type phases) has been systematically investigated through a combination of single‐crystal X‐ray diffraction studies and composition analysis (energy‐dispersive X‐ray spectroscopy [EDS]). Ni 1+ δ (In/Sn) ( δ = 0.2–0.4) adopt incommensurately modulated structure and their structures can be described within the 3 + 1‐dimensional orthorhombic superspace group , where the average structure exhibits lattice parameters of , , with a unit cell volume 149 Å 3 . The structure is related to NiAs‐type arrangement Ni(1)(In1/Sn1) and additional nickel (Ni(2)) atoms partially occupying trigonal bipyramidal interstices in an ordered fashion. The modulation vector * ( = 0.41−0.47) governs the occupational modulation of the Ni(2) sites, which is successfully modeled using a Crenel function. Increasing the nickel content (60 at%) induces a structural transition from the incommensurately modulated phase to a commensurately modulated phase. The commensurate phase is related to the binary Fe 1.66 Sn structure type (). The structure of commensurately modulated Ni 1.5 (In/Sn) adopts the orthorhombic space group with lattice constants a = 7.1 Å, b = 5.2 Å, c = 8.2 Å with NiAs‐type arrangement Ni(1)(In/Sn) and additional Ni(2)/Ni(3) atoms partially occupying trigonal bipyramidal interstices, leading to the formula Ni(1)((Ni(2)/Ni(3)) δ (In/Sn).