Polycrystalline samples of Ca0.9−xSrxYb0.1MnO3−δ (x=0, 0.025. 0.05, 0.1, and 0.2) were prepared by a conventional solid-state reaction and their thermoelectric properties were evaluated at 303–973 K. Each of the samples consisted of a single phase with an orthorhombic structure. All the samples showed a metallic conductivity and their electrical resistivity was markedly affected by the distortion of the MnO6 octahedron. The Seebeck coefficient of all the samples was negative, indicating that the predominant carriers were electrons over the entire temperature range examined. The highest power factor achieved (0.22 mW m−1 K−2 at 773 K) was shown by the sample with x=0.1. The thermal conductivity was affected by both the crystal distortion and the difference in mass between the Ca2+ and Sr2+ ions. The highest dimensionless figure of merit obtained was 0.09 at 973 K for the sample with x=0.1; this is a result of its low electrical resistivity and its moderate Seebeck coefficient and thermal conductivity.

An intermediate-temperature o C) operation of solid oxide fuel cells (SOFCs) is considered to be one of the solutions for reducing a SOFC apparatus cost. In order to achieve this, we proposed to use proton conductive thin films as an electrolyte. As a substrate is required a fuel gas permeability, porous substances are used as substrate, in general. However, this makes depositing solid electrolyte quite difficult. In this paper, we will mention our proposals for avoiding this difficulty. One of our proposals is a direct deposition on a polished porous substrate by liquid-delivery metal-organic chemical vapor deposition (LD-MOCVD). The other is a sol-gel deposition of SZYO thin films on Pd plated porous substrate. Based on these new SOFC structures, we believe we can obtain good SOFC operations in a near future.

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