Extended semiconducting behaviour of Ba0.85Sr0.15Ti0.9Fe0.1O3 thick films in large temperature range

International audienceBa0.85Sr0.15Ti0.9Fe0.1O3 (BSTF) powder has been synthesized by solid-state reaction in aim to develop lead-free semiconductor gas sensors. Thick BSTF films were therefore deposited on alumina substrates coated by silver–palladium (Ag–Pd) bottom electrodes and then sintered at 1100 °C for 2 h. These films were physically and electrically characterized. The dielectric constant, loss tangent and conductivity evolutions were investigated in extended frequency and temperature ranges and compared to results given by a non doped barium titanate thick film. A huge increase of the BSTF conductivity variation, by a factor of 10,000 at low frequency when the temperature ranges from 25 to 500 °C, was observed. This behaviour, associated to a relaxation mechanism governed by the migration of oxygen vacancies, has led to a drastic change of the BSTF conductivity