Ce(1-x)M(x)O(2) (M = Ti, Zr, and Hf) nanomaterials with controlled morphology and composition were synthesized by a two-step route for the first time. These nanomaterials exhibit high activities for hydrogen reduction and ethanol reforming reactions, and therefore, they may be useful for applications in catalysis and solid oxide fuel cells.

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Quaternary selenides of Pb(4)In(x)M(6-x)Se(13) (M = Bi, x = 2.1-2.8; Sb, x = 2) were synthesized by solid-state methods, and their structures were determined from X-ray diffraction of single crystals. These compounds are isostructural with Pb(4)In(2)Bi(4)S(13) and crystallize in orthorhombic space group Pbam (No. 55) with Z = 4; the structure features a three-dimensional framework consisting of Z-shaped ribbon units and corner-sharing infinite one-dimensional [InSe(4)](infinity) chains running parallel to the c-axis, which are connected by Pb atoms to form a three-dimensional structure. Calculations of the band structure and measurements of Seebeck coefficient, electrical conductivity, and diffuse reflectance spectra confirm that these compounds are semiconductors with a narrow band gap. All compounds show semiconducting properties; the Seebeck coefficient of Pb(4)In(2.5)Bi(3.5)Se(13) is -180 microV/K at 295 K.

Ternary chalcogenides, GeSb2Se3 and Ge3Sb4Se7, were synthesized and characterized. These chalcogenides are the first ternary selenides in a ternary Ge–Sb–Se system that feature a layer structure related to black phosphorus and SnSe-type structures. Both compounds contain a ∞ 1[Sb2Se2]2– unit with Sb+ cations in a zigzag Sb–Sb chain structure, and Sb3+ cations in a distorted NaCl100-type of ∞ 1[Ge n–2Sb2Se n ]2+ unit (n = 4, 5). These materials exhibit n-type semiconducting properties with thermal conductivity significantly lower than that of GeSe and Sb2Se3, which could be correlated to the 1D Sb+ chain and disordered sites with different Ge/Sb compositions. It is anticipated that these newly discovered ternary chalcogenides may provide unique properties with enhanced thermoelectric properties.

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