Physical Properties and Bonding in RE₃TiSb₅ (RE = La, Ce, Pr, Nd, Sm)

Electrical transport and magnetic properties have been measured for the family of ternary rare-earth transition-metal antimonides RE 3 TiSb 5 ( RE = La, Ce, Pr, Nd, Sm). Single-crystal X-ray structures have now been determined for all members of this series. All are metallic, with anomalies appearing in the resistivity curves suggestive of electronic transitions. La 3 TiSb 5, Ce 3 TiSb 5, and possibly Nd 3 TiSb 5 undergo transitions to a superconducting state below ∼4 K. Support for the existence of a superconducting phase is also provided by onset of diamagnetism in the magnetization behavior below T C . Extended Hückel band structure calculations disclose strongly anisotropic electrical conductivity, reflecting the one-dimensional character of covalent bonding within the structure, and reveal the presence of narrow Ti-based bands close to the Fermi level.