Hypervalent Bismuthides La 3 MBi 5 (M = Ti, Zr, Hf) and Related Antimonides: Absence of Superconductivity.

We successfully synthesized the ternary bismuthides La3 MBi5 (M = Ti, Zr, Hf). These compounds crystallize in the hexagonal Hf5 Sn3 Cu-anti type structure (space group: P63 /mcm) consisting of face-sharing MBi6 octahedral chains and hypervalent Bi linear chains, both separated by La atoms. Magnetic susceptibility and electrical resistivity measurements revealed that all of the compounds, including the solid solution La3 Ti(Bi1-x Sbx )5 , exhibit a Pauli paramagnetic behavior without any trace of superconductivity down to 1.85 K, as opposed to a recently reported 4 K superconductivity in La3 TiSb5 . The absence of superconductivity is supported by first-principles band calculations of La3 TiBi5 and La3 TiSb5 that demonstrate similar electronic structures with three-dimensional Fermi surfaces.