Thermoelectric performance of In and Ga single/dual-doped ZnO ceramics fabricated by spark plasma sintering

In single-doped [Zn(1−y)Iny]O (y = 0.005, 0.01, 0.02, 0.03, 0.05) ceramics and In and Ga dual-doped [Zn(1−x−y)GaxIny]O (y = 0.005; x = 0.005, 0.01, 0.02, 0.03, 0.05) ceramics were prepared using a solid-state reaction and spark plasma sintering at 1423 K in vacuum. The microstructural and chemical composition analyses revealed that Zn7In2O10 and ZnGa2O4 existed as the secondary phases in the single-doped ZnO (y ≥ 0.02) and dual-doped ZnO (y = 0.005; x ≥ 0.02) ceramics. Doped (single and dual) ZnO showed a high relative density of 92.5–100% as compared to pure ZnO (91.3%). The dual-doped sample with x = 0.005 and y = 0.005 prepared at 1046 K showed the highest power factor of 1.05 mW K−2 m−1. The dual-doped ZnO ceramics thereby showed an improved thermoelectric performance, attaining the figure of merit of 0.17 as compared to that of pure ZnO (0.12) at 1046 K.