Identification of the new intermetallic compounds Y3Ni4B4C3 and Y1Ni1B1C1;: related homologous series (LnC)m(B-Ni2-B)n

On the idea of material designing, we have succeeded in synthesizing Y3Ni4B4C3 with a new crystal structure and Y1Ni1B1C1 phases through phase search experiments. The Y3Ni4B4C3 phase is a tetragonal layer-like structure that is built up of one half Y1Ni2B2C1 unit and one full Y1Ni1B1C1 unit stacked along the c-axis. For the Y3Ni4B4C3 phase, the possible space group is I4 (No. 79), lattice parameters are a = 0.355190(7) nm and c = 2.56453(7) nm. For the Y1Ni1B1C1 phase with a CeFeSi type structure, lattice parameters are a = 0.35660(5) nm and c = 0.75625(12) nm. The crystal structure of Y3NI4B4C3 corresponds to the T* phase of the cuprate high T-c superconducting materials and m = 3, A = 2 in the homologous series (LnC)(m)(B-Ni-2-B)(n). By magnetic susceptibility measurements, superconducting transitions were observed at around 11.0 and 3.0 K. Although the Y1Ni2B2C1 phase was included in the sample and the single phase was not obtained yet, it is considered that the Y3Ni4B4C3 or the Y1Ni1B1C1 phase shaw a superconducting transition. (C) 1997 Elsevier Science B.V.