Modified texture and high temperature transport properties of doubly substituted BaxAgyCa2.8Co4O9 thermoelectric oxide

Doubly substituted polycrystalline compound bulk samples of BaxAgyCa2.8Co4O9 were prepared via citrate acid sol-gel method followed by spark plasma sintering. The phase composition, orientation, texture and high temperature electrical properties were systematically investigated. The results showed that the orientation and the texture could be modified by altering ratio of Ba to Ag. The resistivity and the Seebeck coefficient of substituted samples were decreased by decreasing Ba/Ag ratio except for that of Ba0.1Ag0.1Ca2.8Co4O9 sample with lowest electrical resistivity (7.2 m Omega cm at 973 K), moderately high Seebeck coefficient (172 mu V/K at 973 K) and improved power factor (0.42 mW/mK(2) at 973 K). (C) 2009 Elsevier B.V. All rights reserved.