The metallic Zintl phase Ba3Sn4As6

The ternary Zintl compound barium tin arsenide, Ba3Sn4As6, has been synthes ized at 950 degreesC, and its structure has been determined by single-cryst al X-ray diffraction methods. It crystallizes in the monoclinic space group C-2h(5) - P2(1)/n with a = 8.6374(10) Angstrom, b = 18.3536(13) Angstrom, = 9.7209(11) Angstrom, B = 90.05(2)0, and Z = 4 at 220C. The structure of B agSnqAsg can be regarded as an intermediate between the hypothetical limiti ng structures "Ba4Sn2As6", containing one-dimensional corner-sharing chains of Sn-centered tetrahedra and "Ba2Sn6As6", containing two-dimensional corr ugated layers with pentagonal channels. The Ba2+ cations separate these cha ins or layers. Resistivity measurements indicate weakly metallic behaviour for Ba3Sn4As6 with a room-temperature resistivity of 2.7 x 10(-4) Omega cm. (C) 2001 Editions scientifiques et medicales Elsevier SAS. All rights rese rved.