Synthesis and crystal structures of the layered I–III–V Zintl phases, K4In4X6, where X = As, Sb

Abstract

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 [In₄As₆^4–]_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, ρ_c= 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, ρ_c= 4.62 g cm^–3 at T= 299 K, R= 0.042 for 3001 unique observed reflections.