Investigations on the thermoelectric transport properties in the hole-doped La${}_2$CuO${}_4$

Compared with the traditional thermoelectric semiconductors, the research progress of thermoelectric oxides with high-temperature thermal stability is far behind. In this work, a layered copper oxide La${}_2$CuO${}_4$ was synthesized by combining the high-energy ball milling, solid state reaction and spark plasma sintering. By introducing metal elements (Ba, Sr, Pb) at La site, the increased carrier concentration with optimized electrical transport properties were achieved in La${}_2$CuO${}_4$-based thermoelectric oxides. Results showed that Ba has the best doping effect among the three dopants, with an optimal carrier concentration of ∼10${}^{20}$ cm${}^{-3}$. Furthermore, the figure of merit (ZT) value was enhanced over the entire temperature range with a maximum ZT${}_{ave}$ of ∼0.03 at 300-923 K, which is nearly two orders of magnitude higher than that of printine La${}_2$CuO${}_4$. Our research has successfully developed the thermoelectric properties of La${}_2$CuO${}_4$-based oxide, which has the great potential to be a reliable candidate as the thermocouple for high-temperature detection in the key parts of aircrafts. (© 2022 Wiley‐VCH GmbH)