A novel conducting ceramics Sm0.9Sr0.1Al0.5Mn0.5O3－δ (SSAM9155) was prepared by the organic gel method combined with a solid state sintering technique. The thermal decomposition and phase inversion processes of the gel precursors, crystal structure, phase stability against reduction and microscopic morphology of the sinters were studied by using TG/DTA, FTIR, XRD and SEM. The electrical conductivities of sintered ceramics in both air and H2 were measured by the direct current four-wire method, and the electronic transport mechanism in this conducting ceramic was investigated. The experimental results show that the well-crystallized nanopowders with tetragonal perovskite structure can be obtained by calcining the gel precursors at 900 ℃ for 5 h. The electrical conductivity of SSAM9155 ceramics is dominated by P-type electronic conduction and increases with temperature, indicating that the mechanism of electronic transport is the hopping of p-type small polaron. With increasing calcination temperature and prolonging soaking time, both the electrical conductivity and relative density of SSAM9155 ceramics become larger initially and then decrease. The sample sintered at 1600 ℃ for 10 h has the highest relative density of 98% with electrical conductivity reaching 8.21 S•cm－1 in air and 1.26 S•cm－1 in H2 at 850 ℃. The apparent activation energies for SSAM9155 in air and H2 were calculated to be 0.265 and 0.465 eV, respectively. The Sr- and Mn-doped SmAlO3 with relatively high conductivity may be used as a potential anode material for solid oxide fuel cell (SOFC).

Key words: conducting ceramics, Sr- and Mn-doped SmAlO3, organic gel method, mixed conducting property, SOFC anode