High Temperature Transport Property of Copper site Doped La2CuO4

Abstract

The transport properties of p‐type polycrystalline La2Cu1−xMxO4 (MCo and Mn) have been investigated in the high temperature domain above room temperature up to 973 K. The electrical resistivity of La2Cu1−xMxO4 undergoes a temperature driven semiconducting (insulating) to metallic transition at high temperature (∼750 K) and a doping induced metal to semiconductor transition at room temperature. The Arrhenius plot of the ln(ρ/T)∼1/T shows a conducting mechanism and in the La2Cu1−xMxO4 (M:Co and Mn) a transition temperature was found at around 750 K similar to what was observed in the La2−xRExCuO4 (RE: Pr, Nd and Y) system. We therefore suggest that in these doped ceramics the metal–insulator (semiconductor) transition at ∼750 K should be attributed to combined effects of a strong phonon scattering mechanism due to thermal activation, oxygen vacancies and structural disorders. Furthermore, a site‐dependent influence of electrical resistivity in La2CuO4‐based ceramics was distinguished by combining thermoelectric measurements and X‐ray absorption spectroscopy. The doping induced transition is then associated with large imperfections present in the CuO2 layer, consistent with a dominant role of the single CuO2 layer in the charge transport mechanism of La2CuO4‐based materials.

Investigations on the Thermoelectric Transport Properties in the Hole‐doped La2CuO4

“…[18] In addition, by doping Co and Mn at Cu site using a two-step chemical method, Xu et al found two physical changes in resistivity with temperature and doping concen-tration, and the electrical transport properties could be further optimized by controlling the doping content on Cu site and adjusting the oxygen vacancy. [19] However, the thermoelectric performance of La 2 CuO 4 is still relatively lower, a further optimization is needed.…”