Syntheses, crystal and electronic structures of three new potassium cadmium(II)/zinc(II) tellurides: K2Cd2Te3, K6CdTe4 and K2ZnTe2

Three new ternary potassium(I) zinc(II) or cadmium(II) tellurides, namely, K2Cd2Te3, K6CdTe4 and K2ZnTe2, were synthesized by solid-state reactions of the mixture of pure elements of K, Cd (or Zn) and Te in Nb tubes at high temperature. K2Cd2Te3 belongs to a new structure type and its structure contains a novel two-dimensional [Cd2Te3]2- layers perpendicular to the b-axis. K(5) cation is located at the center of five member rings of the 2D [Cd2Te3]2- layer, whereas other K+ cations occupy the interlayer space. K6CdTe4 with a K6HgS4 type structure features a 'zero-dimensional' structure composed of isolated CdTe4 tetrahedra separated by the K+ ions. K2ZnTe2 in the K2ZnO2 structural type displays 1D [ZnTe2]2- anionic chains of edge sharing [ZnTe4] tetrahedra separated by the potassium(I) ions. K2Cd2Te3, K6CdTe4 and K2ZnTe2 revealed a band gap of 1.93, 2.51 and 3.0 eV, respectively. - Graphical abstract: Three new semiconducting K-Zn(Cd)-Te phases were synthesized. They feature 2D, 1D or 0D anionic structure made of corner- and edge-sharing or isolated MTe4 tetrahedra.