Dimensional reduction in II-VI materials: A₂Cd₃Q ₄ (A = K, Q = S, Se, Te; A = Rb, Q = S, Se), novel ternary low-dimensional cadmium chalcogenides produced by incorporation of A ₂Q in CdQ

The synthesis of the isomorphous, layered chalcogenides K ₂Cd₃S₄ (I), Rb₂Cd₃S ₄ (II), K₂Cd₃Se₄ (III), Rb ₂Cd₃Se₄ (IV), and K₂Cd ₃Te₄ (V) in molten A₂Q_x fluxes is reported (A = K, Rb; Q = S, Se, Te; x = 2 to 3). The compounds form as (Cd ₃Q₄)_n^2n- layers interspersed with A⁺ cations; the layers are composed of Cd₃Q ₄^2- units shaped as truncated cubes. The compounds have room-temperature band gaps of 2.75, 2.92, 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 context is presented to connect all these different types of compounds.