Microstructura and electrical properties of the composites based on SrTi sub(0.5)Fe sub(0.5)O sub(3 - delta ) and Ce sub(0.8)(Sm sub(0.8)Sr sub(0.2)) sub(0.2)O sub(2 - delta )

New composite materials with mixed oxygen ionic and electronic conductivity based on perovskite SrTi sub(0.5)Fe sub(0.5)O sub(3 - delta ) and fluorite Ce sub(0.8)(Sm sub(0.8)Sr sub(0.2)) sub(0.2)O sub(2 - delta ) were prepared by mixing base components synthesized by the solid state reaction method with following joint calcination at 1573 K and sintering in a gas-tight ceramic at 1623-1823 K. The phase content microstructure and surface morphology, thermal expansion of sintered samples and their electrical properties were investigated by XRD, scanning electron microscopy, dilatometrie method and four-probe dc technique, respectively. It was found that the composite materials are two-phase perovskite-fluorite systems with chemically stable content, characterized by the smallness of grain size relative to Ce sub(0.8)(Sm sub(0.8)Sr sub(0.2)) sub(0.2)O sub(2 - delta ) and considerably higher microhardness in comparison with SrTi sub(0.5)Fe sub(0.5)O sub(3 - delta ). They possess intermediate values of thermal and chemical expansion, and high level of ionic and n-type electronic conductivity, making these composite materials promising candidates as mixed ionic and electronic conducting ceramic membranes for a wide variety of gas separation applications, including oxygen separation, partial oxidation of methane and hydrogen separation and as anodes for solid oxide fuel cells (SOFCs).