Transmissionsoptimierte Einkristallstrukturbestimmung und elektronische Struktur von Bi3Ni / Transmission-Optimized Single-Crystal Structure Determination and Electronic Structure of Bi3Ni

Abstract

Crystals of Bi3Ni were synthesized using iodine as mineralizer. X-ray diffraction on a single-crystal including transmission-optimized measurement and optimized absorption correction (μ(Mo-Kα) = 1302 cm−1) results in a structure model (Pnma; a = 887.96(7), b = 409.97(3), c = 1147.8(1) pm) with significant deviations in interatomic distances compared with previous data from X-ray and neutron investigations. From quantum chemical calculations and from the structural chemistry of the subhalides related to Bi3Ni the chemical structure of the intermetallic compound can be derived. In the crystal structure the Ni atoms have a capped trigonal prismatic coordination of Bi atoms with strong bonds Ni-Bi and Ni-Ni. The prisms constitute rods 1 ∞ [NiBi1/1Bi6/3] by sharing the non-capped square faces. The bonding between the intermetallic rods is clearly weaker than inside them, leading to a preservation of this structural fragment in the subhalides of Bi3Ni. In accordance with the low temperature superconductivity of the compound, its electronic band structure shows steep and flat bands at the Fermi level. DFT and ELF calculations reveal a separation of delocalized conduction electrons inside the prism rods and largely localized valence electrons between them.