Novel La1−xCaxTi1−yTayO3-δ perovskites with enhanced conductivity for solid oxide fuel cell electrodes

Abstract

The novel La1−xCaxTi1−yTayO3-δ nano perovskites with high oxygen vacancies have been prepared for solid oxide fuel cells (SOFCs) by facile hydrothermal method. To enhance the oxygen vacancies, structural, thermal and chemical stability, the phase composition of the materials was varied with multiple x & y values like (0, 0.2, 0.4, 0.6, 0.8 and 1). All the as prepared compositions of La1−xCaxTi1−yTayO3-δ were undergone heat treatments in autoclave, calcined at 700 °C and sintered at 1000 °C. These modified perovskite oxides can add in hefty point defects, such as oxygen vacancies that compensate dopants or are part of an inherent off-stoichiometry. These defects have high mobilities in La1−xCaxTi1−yTayO3-δ perovskites, making it most suitable for electrochemical energy conversion devices. The appropriate phase purity, structural properties, lattice parameters and morphology of the perovskite were inspected. Electrical conductivity of sintered pellets was analyzed using electrochemical impedance spectroscopy. The electrical behavior of La1−xCaxTi1−yTayO3-δ is enhanced at lower operating temperature and long-term structural stability, phase purity is also improved owing to the inclusion of Calcium and Tantalum (La1-xCaxTi1−yTayO3-δ). The enhancement in electrical conductivity, electro-catalytic activity is credited by means of partial replacement of Ca and Ta in the perovskite structure. Among them, La0.6Ca0.4Ti0.6Ta0.4O3-δ showed the maximum conductivity of 9.18 × 10-2 S cm-1 at 750 °C. These results demonstrate that the La1−xCaxTi1−yTayO3-δ perovskites are capable as electrode material intermediate temperatures SOFCs fabrication.