Synthesis and characterization of cold sintered Ca3Co4O9 ceramics obtained by a simplified Pechini route

Cold sintered Ca3Co4O9 ceramics obtained by the simplified Pechini route. For the cold sintering process (CSP), the samples were pressed at 350 MPa and sintered at 150 oC for 1 h (CSP/0). After the CSP, two of these samples were conventionally resintered at 900 degrees C for 6 h (CSP900/6) and 24 h (CSP900/24). The ceramics CSP/0 presented a relative density of 74 %. Regarding the grain size, the ceramic CSP/0 presented an average grain size of 0.60 & mu;m, and compared to the conventional sintering method, the cold sintered ceramics exhibit higher electrical conductivity (3785 S/m) and lower thermal conductivity (0.85 W/mK). It was possible to conclude that the cold sintering method was able to produce Ca3Co4O9 ceramics with higher density values than in the conventional process. Finally, the ceramics produced by the CSP presented a ZT value of 0.084 at 600 degrees C, which is higher than the conventional one.