Synthesis and characterization of the Zintl phase Na4Ba3As6 with isolated As35- anions

The title compound was prepared by direct fusion of the corresponding elements at 800degreesC followed by slow cooling to room temperature. It crystallizes in the orthorhombic space group Pbcm (No. 57) with a = 11.340(2), b = 8.745(2), and c = 14.920(2) Angstrom, V = 1479.8(5) Angstrom(3), and Z = 4. The structure is made of isolated V-shaped trimers As-3(5-) and sodium and barium countercations. According to magnetic and resistivity measurements, Na4Ba3As6 is a narrow-gap semiconductor, i.e. a closed-shell compound that fulfills the Zintl concept. (C) 2003 Elsevier Inc. All rights reserved.