Gas-sensing and electrical properties of perovskite structure p-type barium-substituted bismuth ferrite

Pure and Ba-substituted bismuth ferrite (BiFeO₃, BFO) powders were successfully synthesized via a sol-gel method. The effects of the Ba-substitution on the morphology, gas-sensing and electrical properties of BFO were studied. The gas-sensing tests show that the sensor based on Bi_0.9Ba_0.1FeO_2.95 (BBFO10) has high sensitivity, quick response, effective selectivity and excellent long-time stability. The conduction mechanism and gas-sensing mechanism of a BBFO10 sample were investigated by the impedance spectroscopy and it was found that the conduction is dominated by p-type hole conduction. The conductivity of the sensor is dependent on the oxygen partial pressures and the type of gas atmosphere. The enhanced gas-sensing performances of the BBFO10 sensor are attributed to the higher oxygen vacancy concentration which was induced by the substitution of Bi³⁺ ion by an aliovalent Ba²⁺ ion at the A-site of the perovskite structure.