The Transport Properties and Defect Chemistry of La2-XSrXCuO4-δ

Abstract

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.