Conductivity and Structure Correlation in Gd2Zr2O7 Pyrochlore for Oxide Fuel Cell Technology

Abstract

AbstractEnergy production using solid oxide fuel cells (SOFCs) technology is the most promising highly efficient and cost-effective clean source of energy to reduce the greenhouse gas emissions and the fossil fuel use. However, novel oxide-ion electrolytes having low operating temperature and high ionic conductivity at the intermediate temperatures is desired. The fluorite type structured materials can accept relatively large amount oxygen vacancy, could be promising candidate for intermediate temperatures oxide-ion electrolytes. Here, conductivity and structure correlation in Gd2Zr2O7 pyrochlore prepared using standard solid state reaction technique is presented. Structure, micro-structure and conductivity of the as-prepared highly dense Gd2Zr2O7 pyrochlore are investigated using XRD, SEM and impendence spectroscopy techniques. Structural analysis confirms that Gd2Zr2O7 consists of single-phasic pyrochlore structure. SEM micrograph exhibits spherical shaped well separated grain having distinct grain-boundaries with a very compact in structure. The variation in ac conductivity of Gd2Zr2O7 with frequency shows a dispersive behaviour of ac conductivity which is similar for both the temperatures (475 °C and 500 °C). Further, the impedance analysis of Gd2Zr2O7 provides conductivity values are 1.04 × 10–3 (Ωm)−1 and 2.13 × 10–3 (Ωm)−1 at temperature of 475 °C and 500 °C, respectively. The observation of high value of conductivity in the moderate temperature range confirms the utilization of pyrochlore structured materials in SOFCs industry.KeywordsPyrochloreSolid oxide fuel cellsHydrogen energyX-ray diffractionImpendence spectroscopy