Dimensional reduction in II-VI materials: A(2)Cd(3)Q(4) (A=K, Q=S, Se, Te; A=Rb, Q=S, Se), novel ternary low-dimensional cadmium chalcogenides produced by incorporation of A(2)Q in CdQ

The synthesis of the isomorphous layered chalcogenides K2Cd3S4 (I), Rb2Cd3S4 (II), K2Cd3Se4 (III), Rb2Cd3Se4(IV), and K2Cd3Te4(V) in molten A(2)Q(x) fluxes is reported (A = K, Rb; Q = S, Se, Te; x = 2 to 3): The compounds form as (Cd(3)Q(4))(n)(2n-) layers interspersed with A(+) cations; the layers are composed of Cd(3)Q(4)(2-) units shaped as truncated cubes. The compounds have room-temperature band gaps of 2.75, 2.93, 2.36, 2.37, and 2.26 eV for I, II, III, IV, and V, respectively, and also display strong photoluminescence. The thermal analysis data for all compounds are reported. The properties of these compounds are compared with those of the three-dimensional compounds CdS, CdSe, and CdTe, as well as those of the nanometer-sized CdQ clusters. A conceptual contest is presented to connect all these different types of compounds.