Improving physical properties of cubic InO1.5-stabilized zirconia by alloying with MoO3

InO1.5-stabilized zirconia (InSZ) possess high ionic conductivity at intermediate temperatures and thus it is a potential candidate for use as electrolyte for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). However, the technological application of InSZ is restricted by its low phase stability and poor physical properties. In this study, the effect of codoping with MoO3 on the microstructure and properties of a series of cubic InSZ samples were investigated. We observe that the lattice parameter was not dependent on the concentrations of InO1.5 and MoO3 and in all of the InSZ samples codoped with MoO3 there was stabilization of the cubic phase with an average lattice parameter of 0.5116 nm. With respect to the physical properties, the addition of MoO3 to the cubic InSZ resulted in a 13.5% increase in the hardness and 9% increase in the thermal expansion coefficient. In addition to these improvements, the most important result was an increase of about one order of magnitude in the ionic conductivity of InSZ after the addition of MoO3. As will be demonstrated herein, all of the improvements are associated with the action of the codopant MoO3 in relation to changes in the microstructure of the InSZ cubic matrix.