René Tölke

Electric-field-induced current-voltage characteristics in electronic conducting perovskite thin films

Mixed ionic-electronic conductors (MIECs) such as the (La,Sr)(Co,Fe)O3−d perovskite family are well described in their charge transport through their high temperature applications, i.e., as solid-oxide fuel cell electrodes (600–1000 °C). In this study, the current-voltage (I-V) profiles of these well-known MIEC perovskites are studied between room temperature and 150 °C under bias of ±15 V for potential applications in resistance random access memories. The impact of the metal-oxide interface on the I-V characteristics ranging from ohmic to non-linear hysteretic is discussed for metals of varying work functions and redox potentials, as well as changes in metal electrode distances and areas.

Residual stress and buckling patterns of yttria-stabilised zirconia thin films for micro-solid oxide fuel cell membranes

Introduction Micro-solid oxide fuel cells (micro-SOFCs) have drawn much attention in the last 5 years as promising energy conversion systems for powering small portable electronic devices [1-4]. Micro-SOFCs consist of a thin freestanding cathode-electrolyte-anode assembly (typically <1 μm) prepared by microfabrication techniques used in silicon technologies (Fig. 1). One crucial factor is the thermomechanical stability of these thin-film membranes during microfabrication and device operation. In this study, the thermomechanical properties of freestanding yttria-stabilised-zirconia (YSZ) thin-film membranes deposited by pulsed laser deposition (PLD) for application in micro-SOFCs are investigated and the experimental observations regarding the buckling patterns are simulated.