Syntheses, Structures And Optical Properties Of [A_xM_yM'_y'～Q_z] Selenides

The major contribution in this paper is the synthesis of novel [AxMyM'y'Qz] multi-component metal selenides by the method of solid state synthesis.1. By analyses of EDS of nineteen novel [AxMyM'y'Qz] multi-component metal selenides we have synthesized, including eleven ternary metal selenides, eight quaternary metal selenides, which are KNbSe5, K3Sn3Se7, K2Zr2Se9, K2Ge4Se8, K3Ge2Se9, KTi10Se6, K7Ag2Se8, K9SnSe7, K3In2Se7, CuInSe2, Ag8GeSe and K2TiCu2Se4, KMnAgSe2, K12NbBi2Se3, K2TiAg2Se4, KAg2Bi3Se7, K2CuIn2Se6, K2BiSn4Se6, K5TiAg6Se24, respectively.2. Single crystal structures of two new multi-metal polychalcogenides were determined by X-ray diffraction. K2Ge4Se8 crystallized in the monoclinic space group P21/c with unit cell parameters a = 0.73752(5) nm, b = 1.2239(2) nm, c = 1.7468(4) nm, β = 96.02(3)°, V = 1.5680(5) nm3, Z = 4. K2Ge4Se8 has a layered crystal structure containing two-dimensional networks, 2∞[Ge4Se8]2- anions separated by potassium cations. The layers are packed in the sequence ABAB in the crystal. K2CuIn3Se6 crystallized in monoclinic space group C2/c with cell parameters a = 1.1484(2) nm, b = 1.1458(2) nm, c = 2.1327(4) nm, V = 2.7802(1) nm3, Z = 8. The crystal structure of K2CuIn3Se6 is constructed by packing neutral [K2AgIn3Se6] layers parallelling to (001) plane along the c-axis direction through intermolecular force. 3. The optical properties of K2Ge4Se8,K2CuIn3Se6 were studied by reflective spectrum. The results indicate the energy gap of K4Ge3Se8 is 1.8 eV, the energy gap of K2CuIn3Se6 is 1.6 eV.4. The rule of solid state synthesis was also discussed at last.