Tailoring strength and ionic conductivity in zirconia‐based solid oxide electrolytes using a multimaterial approach

Abstract A multimaterial approach is explored for tailoring the mechanical and functional properties of zirconia‐based ceramic electrolytes to be employed in electrochemical solid oxide cells (SOCs). The combination of alumina‐toughened zirconia (ATZ) surface layers with an embedded 8 mol% yttria‐stabilized zirconia (8YSZ) core layer introduces compressive residual stress in the electrolyte surface upon cooling from sintering. Biaxial bending is employed to assess the strength distribution in the multimaterial architectures compared to the monolithic counterparts. Electrochemical impedance spectroscopy is used to measure the ionic conductivity of the samples in the temperature range between 600°C and 1000°C. The effect of alumina addition is investigated in samples containing ATZ surface layers with 10 vol% or 20 vol% alumina. Experimental results show that the strength of multimaterial electrolytes can be increased by up to ∼30% compared to the monolithic 8YSZ electrolyte, while holding similar overall ionic conductivity compared to the 8YSZ base material. The approach presented in this work offers new paths to enhance the structural properties of functional ceramics in SOCs, which may also be applied to other systems such as ceramic membranes or ceramic sensors.