Synthesis and crystal structures of the layered I–III–V Zintl phases, K4In4X6, where X = As, Sb
Ternary Zintl phase materials of the formula K4In4X6, where X = As or Sb, have been prepared following a high-temperature procedure. The crystal structure of K4In4As6 has been determined at low temperature and consists of [In4As64–]n sheets of ca. 5 Å thickness insulated by a layer of potassium ions of ca. 3 Å thickness. The crystal structure of K4In4Sb6 has been determined at room temperature and is isomorphous with the K4In4Sb6 compound. For K4In4As6, a= 14.323(3)Å, b= 7.106(2)Å, c= 15.795(3)Å, β= 90.30(2)°, space group P21/c, Z= 4, ρc= 4.44 g cm–3 at T= 100(5) K, R= 0.035 for 2688 unique observed reflections. For K4In4Sb6, a= 15.282(5)Å, b= 7.544(1)Å, c= 16.788(3)Å, β= 90.52(2)°, space group P21/c, Z= 4, ρc= 4.62 g cm–3 at T= 299 K, R= 0.042 for 3001 unique observed reflections.