Ternary antimonide EuSn3Sb4 and related metallic Zintl phases

The ternary Zintl compound europium tin antimonide, EuSn3Sb4, has been synt hesized at 900 degrees C in the presence of a tin Bur, and its structure ha s been determined by single-crystal X-ray diffraction methods. It crystalli zes in the orthorhombic space group D-2h(16)-Pnma with a=9.954(2), b=4.3516 (7), 22.650(4) Angstrom, and Z=4 at 22 degrees C. EuSn3Sb4 is isostructural to SrSn3Sb4; it possesses channels defined by an anionic framework of shar ed SnSb4 tetrahedra, SnSb3 trigonal pyramids, and Sb-Sb zigzag chains, and it is filled by Eu2+ cations, Resistivity measurements indicate weakly meta llic behavior for Asn,sb, (A = Eu, Sr) and the structurally related Ba2Sn3S b6. The anisotropic metallic nature of these compounds is explained through extended Huckel band structure calculations. (C) 2000 Academic Press.