Synthesis and characterization of Ba2SnTe5: A new zintl phase containing unique one-dimensional chains of (SnTe3)(2-) and dimeric units of (Te-2)(2-)

Ba2SnTe5, a novel alkaline-earth-metal tin telluride has been synthesized from a potassium polytelluride salt. Single-crystal X-ray diffraction analysis shows that this compound is a Zintl phase containing unique one-dimensional ''Zweireinfach''-chains of corner-sharing SnTe4 tetrahedra and isolated (Te-2)(2-) dimers. It represents the first ternary alkaline-earth-metal telluride synthesized from a polytelluride flux. Band calculations indicate strong covalent bonding between the Sn and Te within the chain. The interactions between the dimers and the chains are weak and repulsive.