Rapid reactive synthesis and sintering of textured Ca3Co4O9 ceramics by spark plasma sintering

Textured Ca3Co4O9 ceramics were successfully prepared by combination oxalate coprecipitation method and spark plasma sintering (SPS) technique. Single-phase Ca3Co4O9 ceramics with grain aligned can be obtained by spark plasma sintering at 30 MPa, 850 °C for 5 min using the coprecipitation precursor powders calcined at 800 °C for 6 or 8 h. The SPS process is effective sintering technology to obtain pure phase and textured Ca3Co4O9 ceramics. During SPS treatment the densification and reaction occur simultaneously. The thermoelectric properties of the prepared ceramics sample were investigated from 100 to 700 °C. At 700 °C, the electrical resistivity, Seebeck coefficient, thermal conductivity and ZT of the sample prepared by the powders calcined at 800 °C for 8 h are 7.50 × 10−5 Ω m, 165 μV K−1, 1.62 W m−1 K−1, and 0.22, respectively.