Nanoscale Thin Film Electrolytes for Clean Energy Applications

摘要

Ceria and zirconia based systems can be used as electrolytes to develop solid oxide fuel cells for clean energy production and to prevent air pollution by developing efficient, reliable oxygen sensors. In this study, we have used oxygen plasma assisted molecular beam epitaxy (OPA-MBE) to grow samaria doped ceria (SDC) thin films, to understand the role of dopant concentration and geometry of the films towards the ionic conduction in these films. We have also discussed the Gd doped CeO_(2) (GDC) and Gd stabilized ZrO_(2) (GSZ) multi-layer thin films to investigate the effect of interfacial phenomena on the ionic conductivity of these hetero-structures. We found the optimum concentration to be approximately 15 mol(percent) SmO_(1.5), for achieving lowest electrical resistance in SDC thin films. The electrical resistance decreases with the increase in film thickness up to 200 nm. The results demonstrate the usefulness of this study towards establishing an optimum dopant concentration and choosing an appropriate thin film thickness to ameliorate the conductance of the SDC material system. Furthermore, we have explored the conductivity of highly oriented GDC and GSZ multilayer thin films, wherein the conductivity increased with an increase in the number of layers. The extended defects and lattice strain near the interfaces increase the density of oxygen vacancies, which leads to enhanced ionic conductivity in multi-layer thin films.