AbstractLa2‐xSrxCuO4‐δ has been studied to determine the role of dopants and oxygen stoichiometry on the transport properties and defect chemistry of this system. The conductivity was found to reach a maximum for 0.2 < x < 0.3 which reflects a change from electronic to ionic compensation of the Sr dopant at large values of x. A metal to semiconductor transition is observed for x > 0.6 for temperatures below ∼ 600°C. However, the source of this behavior is not clear, given that an increasing amount of second phase was observed for x > 0.4. The conductivity and thermoelectric power (TEP) of La2CuO4 show a Po2⅙ dependence and a temperature independence, implying that the hole mobility is not thermally activated and the enthalpy of oxidation is nearly zero. This last conclusion is confirmed by TGA data.
Defect chemistry and transport properties of perovskite-type oxides La1−xCaxFeO3−δ