Yttria stabilized zirconia thin film as solid oxide fuel cell electrolyte: Temperature dependent structures and morphology

Abstract

Fuel Cell is an electrochemical cell that supports clean and alternative energy that is mushrooming nowadays. Being a device of clean energy production, highly efficient solid oxide fuel cells (SOFCs) are increasing in demands. It converts the chemical energy into electrical energy in an environmentally-friendly way following green technology route. The SOFCs are one type of technology that has great promise to improve energy efficiency and to provide the society with clean and abundant energy. Yttria-stabilized zirconia (YSZ) is used as the electrolyte in SOFC wherein its synthesis with controlled properties is important to obtain the highest energy efficiency. The overall characteristics of the YSZ thin-film electrolyte in the SOFC are determined by its structures and morphologies. Based on these factors, a series of YSZ thin films were deposited on the sapphire wafer substrate by the dip-coating method and sintered in the temperature range of 900 – 1500 ˚C. The temperature dependent structural and morphological attributes of such thin films were determined and the prepared samples were characterized using XRD, AFM and Raman spectroscopy. The XRD patterns of the samples revealed the change in the crystallinity and phase, with an increase in the sintering temperatures while a tetragonal structure was observed at 1300 ˚C. Furthermore, the Raman spectral analyses supported the XRD results. The AFM morphology analysis of the thin films showed an increase in the grain size from 132.25 to 995.2 nm. The observed temperature-dependent changes in the structures and morphological attributes of these films may be useful for achieving high ionic conductivity required for an efficient SOFC construction.