Effect of the Strontium Content on the Electrochemical Performance of the Perovskite-type Pr_(1-x)Sr_xFe_(0.8)Co_(0.2)O_3 Oxides

摘要

Perovskites of the system Pr_(1-x)Sr_xFe_(0.8)Co_(0.2)O_3 (PSFC) have been investigated in terms of their applicability in intermediate temperature electrochemical devices. The crystal structure, morphology, thermal expansion and electrochemical behavior of these oxides were studied by X-ray diffraction, scanning electron microscopy, dilatometry and AC impedance spectroscopy, respectively. For all compositions, orthorhombic perovskite structure was obtained with a particle size of between 1 and 10 μm. All dilatometric curves showed an increase of the thermal expansion at elevated temperatures pointing out a loss of lattice oxygen. The area specific resistances (ASR) of PSFC/YSZ/PSFC symmetrical cells were determined between room temperature and 850°C. The AC impedance results showed that Pr_(0.6)Sr_(0.4)Fe_(0.8)Co_(0.2)O_3 exhibited the lowest cathodic polarization resistance. The ASR was 0.25 Ω cm~2 at 850°C in air.