Enhancement in thermoelectric characteristics of the misfit-layered cobalt oxide, [(Bi,Pb)2Ba1.8Co0.2O4±ω]0.5CoO2, through Pb-for-Bi substitution

Thermoelectric characteristics of a newly discovered commensurate (q=0.5) misfit-layered oxide, [Bi2Ba1.8Co0.2O4±ω]qCoO2, have been significantly enhanced through partial Pb-for-Bi substitution: such substitution is found not only to reduce electrical resistivity and extend the temperature range for metallic conductivity, but also to raise the Seebeck coefficient. To obtain heavily Pb-substituted samples (up to 20-30% substitution level) requires careful control of both temperature and oxygen partial pressure during synthesis. Upon increasing Pb content, the lattice gets shrunken along the layer-piling (c-axis) direction, while the q value remains constant at 0.5.