title: Superconductivity in ternary chalcogenides Bi(2)Ni(3)X(2) (X = S, Se).
abstract: The physical properties of parkerite and its related compound, Bi(2)Ni(3)X(2) (X =  S, Se), were studied. The electrical resistivity of both compounds shows typical metallic behaviour up to 400 K. The resistivity and specific heat measurements at low temperatures reveal that these compounds are superconducting with a transition temperature of ∼0.7 K. The upper critical fields at 0 K, μ(0)H(c2)(0), are 95 mT (Bi(2)Ni(3)S(2)) and 75 mT (Bi(2)Ni(3)Se(2)). In the normal state, the electronic specific heat coefficient, γ, and the Debye temperature, Θ(D), are found to be 11.4 mJ mol(-1) K(-2) and 189 K, respectively, for Bi(2)Ni(3)S(2), and 12.2 mJ mol(-1) K(-2) and 173 K, respectively, for Bi(2)Ni(3)Se(2). From the electronic specific heat in the superconducting temperature range, it was found these compounds belong to the weak-coupling BCS superconductors.
authors.affiliation: Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Wakeshima
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hinatsu