Mixed ionic-electronic conductivity of La1−xSrxCo1−yFeyO3−δ perovskite-type oxides

Ionic (σi) and electronic (σe) conductivities of mixed conductive La1−xSrxCo1−yFeyO3−δ were separately measured by means of fourprobe ionic dc and ordinary four-probe dc techniques, respectively. At 1073 K, for instance, σi ranged in the order of 1 – 10−2 S cm−1 while σe was around 102 S cm−1, indicating that the present oxides were good mixed conductors with ionic transport number 10−2 – 10−4. σi increased as contents of Sr and Co increased though Sr content was more influential. The apparent activation energy for oxide ion conduction as well as the dependences of σi on oxide composition and oxygen partial pressure suggested that oxide ion conduction occurred via a vacancy mechanism. The relation of mixed conductivity to the oxygen semipermeability was also discussed.