Two Ternary Phases Containing Sb4−2 Ions: Na2M3Sb4, M=Sr, Ba. Synthesis, Structure, and Properties

✍ Scribed by Lisheng Chi; John D. Corbett

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 451 KB
• Volume: 162
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9329

✦ Synopsis

The isotypic compounds Na 2 Ba 3 Sb 4 and Na 2 Sr 3 Sb 4 were prepared by the direct fusion of elements at 7503C followed by slow cooling to, and annealing at, 3003C. These crystallize in the orthorhombic system, space group Pnma (No. 62), with respective lattice dimensions of a ‫؍‬ 8.220(1), 7.919(2) A s ; b ‫؍‬ 17.136(3), 16.526(5) A s ; c ‫؍‬ 9.140(2), 8.801(2) A s ; V ‫؍‬ 1287.5(2), 1151.7(4) A s 3 ; and Z ‫؍‬ 4. The structure of Na 2 Ba 3 Sb 4 was re5ned from singlecrystal X-ray data. All antimony atoms are dimerized as two independent Sb 4؊ 2 units which, together with a Na atom, center quadrilateral prisms of Ba or Sr and Na. The structure can be directly related to that of -Ba 5 Sb 4 (Eu 5 As 4 , Cmca) by an oxidative distortion on cation substitution that allows the dimerization of the isolated Sb 3؊ anions therein. The barium compound is a Zintl phase, being established as diamagnetic and semiconducting ( 294 K570 cm).