- Yanuo Shi, Swiss Federal Institute of Technology Zurich (ETH Zurich)
Solid-state micro-energy convertors such as micro–solid oxide fuel cells are getting increasing attention today as promising applications for clean energy storage and delivery. This work involves electro-chemo-mechanic engineering of ceramic films in an effort to find the best strategy for optimizing the performance of electrolyte thin films and, subsequently, optimizing the design of micro-energy conversion devices. Altering the stoichiometry through extrinsic doping is the classic method to tune the ionic conducting behavior of oxide material. The defect density can also be affected by mechanical strain of thin films. In this work, the proportional relationship between compressive in-plane strain and the activation energy of ionic conductivity was determined for free-standing and substrate-supported samples of gadolinia-doped ceria. The doping concentration of gadolinia was regulated to determine the influence of extrinsic doping level. The influence of these two factors on the ionic transfer of oxide thin films was systematically studied. Based on the results, techniques were explored for tuning mechanical strain to get controllable conductivity through manipulating the micro-morphologies of thin films by different microfabrication techniques.