Synthesis, Structure, and Superconductivity in the New-Structure-Type Compound: SrPt6P2

A metal-rich ternary phosphide, SrPt6P2, with a unique structure type was synthesized at high temperatures. Its crystal structure was determined by single-crystal X-ray diffraction [cubic space group Pa3̅; Z = 4; a = 8.474(2) Å, and V = 608.51(2) Å3]. The structure features a unique three-dimensional anionic (Pt6P2)2– network of vertex-shared Pt6P trigonal prisms. The Sr atoms occupy a 12-coordinate (Pt) cage site and form a cubic close-packed (face-centered-cubic) arrangement, and the P atoms formally occupy tetrahedral interstices. The metallic compound becomes superconducting at 0.6 K, as evidenced by magnetic and resistivity measurements.