Ca3Co4O9 (p-type) and Zn 0.98Al0.02O (n-type) pellets were prepared by conventional sintering (CS) and Spark Plasma sintering (SPS) starting from the oxides. The best p-type sample was SPS Ca3Co4O9 obtained from pre-sintered pellets, with electrical conductivity σ = 144 S/cm and Seebeck coefficient S = 172 μV/K at 800 °C, while thermal conductivity κ = 2.00 W/m×K and figure of merit ZT = 0.23. The best n-type sample was CS Zn0.98Al0.02O showing σ = 83 S/cm and S = -268 μV/K at 800 °C, while = 5.03 W/m×K and ZT = 0.127. The output power of a module based on SPS Ca3Co4O9 and CS Zn0.98Al0.02O legs was 2.26 mW (with T = 500 °C, ΔT = 248 °C).
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