Zr5Sb3-xRux, a new superconductor in the W5Si3 structure type

摘要

We report that at low Ru contents, up to x = 0.2, the Zr5Sb3-xRux solid solution forms in the hexagonal Mn5Si3 structure type of the host (x = 0), but that at higher Ru contents (x = 0.4-0.6) the solid solution transforms into the tetragonal W5Si3 structure type. We find that tetragonal Zr5Sb2.4Ru0.6 is superconducting at 5 K, significantly higher than the transition temperature of hexagonal Zr5Sb3 (x = 0), which has a T-c of 2.3 K. In support of a hypothesis that certain structure types are favorable for superconductivity, we describe how the W5Si3 and Tl5Te3 structure types, both of which support superconductivity, are derived from the parent Al2Cu type structure, in which superconductors are also found. Electronic structure calculations show that in Zr10Sb5Ru, a model for the new superconducting compound, the Fermi level is located on a peak in the electronic density of states.