High-temperature electrical transport behaviors of the layered Ca2Co2O5-based ceramics

Textured Bi-substituted Ca2Co2O5 ceramics have been prepared using a coprecipitation method combined with spark plasma sintering. The Bi substitution is effective in increasing the grain orientation of the Ca2Co2O5-based ceramics (from 0.46 to 0.85). Electrical conductivity increases obviously with partial substitution of Bi3+ for Ca2+ (from 113.9 to 142.4 S/cm at 973 K). The Ca1.92Bi0.08Co2O5 sample exhibits higher power factor (4.4 x 10(-4) W m(-1) K-2) than that of pure Ca2Co2O5 (3.2 x 10(-4) W m(-1) K-2) at 973 K, indicating that the Ca2Co2O5 system is another promising p-type material for high-temperature thermoelectric applications. (C) 2010 American Institute of Physics. [doi:10.1063/1.3425891]