We have prepared polycrystalline [(Ca 1Àx Pb x ) 2 CoO 3:1 ] 0:62 CoO 2 (0 5 x 5 0:03) samples by a conventional solid-state reaction method and investigated the effects of Pb substitution on the thermoelectric and magnetic properties of the samples. With Pb substitution, both electrical resistivity and Seebeck coefficient do not change markedly. This is attributed to the carrier concentration of the samples. Seebeck and Hall coefficient measurements reveal that the major charge carriers in the samples are holes, however, the carrier concentration does not change with increasing x. Neutron powder diffraction and magnetic susceptibility measurements also reveal that Pb ions are in a divalent state in a rock salt-type Ca 2 CoO 3 block layer. The average valence state of Co ions in a CdI 2 -type CoO 2 sheet is 3.1+ and that of Co ions in the block layer is 3.6+. The resulting dimensionless figure of merit for an x ¼ 0:02 sample at room temperature is 0.024, which is approximately equal to the corresponding value of a polycrystalline NaCo 2 O 4 sample.

Nanosized ITO(indium tin oxide) powders were prepared in ethylene glycol solution under mild temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. The average size and distribution of the synthesized ITO powders were about 20 ㎚ and broad, respectively. The phase of synthesized particles was crystalline reacted at 230 0C for 6 h.. The optical properties of the synthesized ITO powders were transparent.

ZnO-SiO2 nanoparticles were synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles was controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average size of synthesized ZnO-SiO2 nanoparticles was in the range of 20-40 nm. The effects of synthesis parameters such as the molar ratio of water to precursor and the molar ratio of water to surfactant are discussed.

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