In this study, Ruddlesden–Popper La0.9Sr1.1Co1−xMoxO4 (x ≤ 0.1) powders were successfully synthesized using a modified sol–gel method. The structural analysis revealed that all samples had a tetragonal phase at room temperature. The electrical conductivity measurements showed that all samples had semiconducting behavior in the range of room temperature to 850°C. Moreover, it was found that the electrical conductivity of the ceramics was enhanced with the increase of Mo doping, at temperatures higher than 300°C up to 850°C. This enhancement of the electrical conductivity can be due to Co3+–O–Mo5+–O–Co2+ double-exchange interaction. The EIS measurements of the symmetrical cells were carried out for x = 0, 0.03 and 0.1 samples at 650°C, 750°C and 850°C. The obtained area specific resistance (ASR) values of La0.9Sr1.1Co1−xMoxO4 on ceria-gadolinium oxide (CGO) electrolyte at 850°C were 0.36 Ω cm2, 0.35 Ω cm2 and 1 Ω cm2 for samples x = 0, 0.03 and 0.1, respectively. These results indicate that the electrical conductivity of pure sample (La0.9Sr1.1CoO4) has been enhanced by Mo substitution in Co ion sites, but limits the oxygen ion transport.

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