Ni₃InSb: Synthesis, Crystal Structure, Electronic Structure, and Magnetic Properties

The ternary phase with the composition Ni₃InSb has been synthesized by high-temperature synthesis and structurally characterized by a combination of X-ray analysis, neutron diffraction analysis, and theoretical calculations. The structure of Ni₃InSb crystallizes in the orthorhombic space group Pnma with lattice constants a = 7.111(3) Å, b = 5.193(3) Å, and c = 8.2113(2) Å. The crystal structure contains ∼20 atoms in its unit cell, which are distributed over four crystallographically independent positions (two Ni, one In, and one Sb). The crystal structure can be considered as a ternary substitutional variant of Ni₃Sn₂ (Pnma, no. 62), where a trivalent In and a pentavalent Sb orderly occupy two tetravalent Sn sites of Ni₃Sn₂. This site decoration pattern of two neighboring elements, In and Sb, is unique and confirmed by first principles total energy calculations. The crystal structure can be described by two building units: Ni₂Sb (building unit of Ni₂In) and NiIn (NiAs-type). They alternate in the crystal structure and form infinite ac-slabs (puckered), and the slabs are stacked along [010]. A triangular lattice formed by Ni atoms indicates the existence of a geometrically frustrated structure. The calculated density of states and crystal orbital Hamilton population enlighten the stability and bonding characteristics of the structure. The temperature-dependent neutron diffraction study down to 5 K reveals that the crystal structure remains in the same orthorhombic symmetry with a weak anomaly in the lattice parameters at ∼100 K. Detailed temperature- and magnetic field-dependent magnetic properties of the title phase Ni₃InSb show spin-glass- or spin-disorder-like behaviors below ∼300 K with an unusual magnetic behavior below 100 K, where an enhancement of magnetization with a decrease of the coercive field has been found.