Abstract
Two new quaternary borocarbide phases were discovered in the Y-Ru-B-C system: the (1111) YRuBC phase of the LuNiBC-type structure with tetragonal lattice parameters a =3.625-3.630 Å and c=7.775-7.874 Å, and the (1221) YRu 2 B 2 C phase of the LuNi 2 B 2 C-type structure with tetragonal lattice parameters a=3.742-3.787 Å and c=10.278-10.453 Å. Bulk superconductivity of 9.7 K was observed from transport and magnetic measurements for the annealed YRu 2 B 2 C sample with a short Ru-Ru bond length d(Ru-Ru) = √2 a/2=2.646 Å. © 1998 American Institute of Physics.