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Limiting current oxygen sensors based on strontium titanate composites have been prepared and their physical properties were investigated in details. B-site deficient yttrium and iron co-doped strontium titanate was prepared to scrutinize the contribution of electronic and ionic features on the electrical conductivity and investigate oxygen ions diffusion in the barrier layer. The mixed conductivity and sensing properties of the aforementioned materials were attentively studied in order to identify the impact of B-site deficiency on the SrTiO 3 -based dense diffusion barrier and therefore performance of the fabricated limiting current oxygen sensors. The obtained results demonstrated that the total conductivity conspicuously increased and the ionic conductivity decreased upon an augmentation in the content of B-site deficiency. The increase of B-site deficiency can accelerate the occurrence of limiting current of the sensors at lower voltages and then elevate the service life of the sensor and promote an independence relationship between limiting current and temperature. Y-doping affects interatomic force in the crystal structure of Y 0 · 08 Sr 0 · 92 (Ti 0 · 6 Fe 0.4) 0.97 O 3-δ and therefore, reduces the diffusion rate of oxygen vacancy which is favorable for development of limiting current oxygen sensor. • The influence of B-site deficiency on mixed electronic-ionic property of Y 0.08 Sr 0.92 (Ti 0.6 Fe 0.4) 1- x O 3-δ (x= 0.01, 0.02, 0.03) was investigated. • B-site deficiency improved electronic conductivity of Y 0.08 Sr 0.92 (Ti 0.6 Fe 0.4) 1- x O 3-δ and can inhibit the growth of grains. • Due to the ionic conductivity and electronic conductivity tested respectively, the possible charge compensation mechanism can be reasonably inferred. [ABSTRACT FROM AUTHOR]