Synthesis and Properties of a New Metal-Rich Nickel Antimonide Telluride or Selenide: Ni7-δSbX2 (δ ≈ 1.3; X = Se or Te)

The two isotypic compounds Ni 5.66 SbTe 2 and Ni 5.72 SbSe 2 have been synthesized by high-temperature reaction of the elements or by using a flux method. They were both characterized by single-crystal X-ray diffraction. Both compounds crystallize in space group I 4/ mmm with Z = 2. Ni 5.66 SbTe 2 (Ni 5.72 SbSe 2 ) has lattice parameters a = b = 3.7824(5) Å and c = 19.244(4) Å ( a = b = 3.7021(5) Å and c = 18.593(3) Å). There is a high concentration of nickel vacancies (≈66%) on one of the three nickel sites (Wyckoff position 4e). Thermopower, thermal conductivity, resistivity, and magnetic susceptibility data for Ni 5.66 SbTe 2 indicate nonmagnetic and metallic behavior.