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 <i>Pa</i>3̅; <i>Z</i> = 4; <i>a</i> = 8.474(2) Å, and <i>V</i> = 608.51(2) ų]. 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