Journal of the American Ceramic Society, Vol.100, No.2, 659-668, 2017
Oxygen-ion conduction in scandia-stabilized zirconia-ceria solid electrolyte (xSc(2)O(3)-1CeO(2)-(99-x)ZrO2, 5x11)
Solid oxide fuel cells (SOFCs) operating at intermediate temperature (500 degrees C-700 degrees C) provide advantages of better durability, lower cost, and wider target application market. In this work, we have studied Sc2O3 (5-11mol%) stabilized ZrO2-CeO2 as a potential solid electrolyte for application in IT-SOFCs. Lower Sc2O3 doping range than the traditional 11mol% Sc2O3-stabilized ZrO2 is an interesting research topic as it could potentially lead to an electrolyte with reduced oxygen vacancy ordering, lower cost, and higher mechanical strength. XRD and Raman spectroscopy was used to study the phase equilibrium in ZrO2-CeO2-Sc2O3 system and impedance spectroscopy was done to estimate the grain, grain boundary, and total ionic conductivities. Maximum for the grain and grain-boundary conductivities as well as the tetragonal-cubic phase boundary was found at 8-9 Sc2O3 mol% in ZrO2-1mol% CeO2 system. It is suggested that the addition of 1mol% CeO2 in the ZrO2 host lattice has improved the phase stability of high-conductivity cubic and tetragonal phases at the expense of low-conductivity t- and -phases.
Keywords:ceria;grain conductivity;grain-boundary conductivity;impedance spectroscopy;scandia;SOFCs;solid electrolyte;stabilized zirconia