Superconductivity in lanthanum nickel boro-nitride

摘要: RESEARCH into intermetallic superconductors has recently been reinvigorated by the discovery of superconductivity at 23 K in a Y–Pd–B–C quaternary alloy1 (tying with long-standing inter-metallic record held Nb3 Ge (ref. 2)), and lower temperatures other boro-carbide alloys based on Ni, Pd Pt3–6. The crystal structure these new superconductors, typified LuNi2B2C 7), consists one square layer rock-salt-type LnC (where Ln stands for rare-earth element) alternating transition-metal boride tetrahedra. Here we report 12–13 system, lanthanum nickel boro-nitride. We have determined formula superconducting La3Ni2B2N3, also related non-superconducting phase LaNiBN. La3Ni2B2N3 is to that LuM2B2C, but three LaN layers alter-nating tetrahedral Ni2B2 layers, an arrangement considerably more two-dimensional than found boro-carbides. These discoveries strongly suggest large number unusual phases are yet be found, materials complex previously considered as candidates superconductivity.