Increasing the stability range of substituted delta-Bi2O3 oxide ion conductors: a high entropy dopant approach.

It has been demonstrated that “stabilised” bismuth oxides can be successfully incorporated into intermediate temperature solid oxide fuel cells. These “stabilised” bismuth oxides generally have lower conductivity than bismuth oxide itself, due to dopant-vacancy interactions, with conductivity significantly decreasing with increasing dopant level. Here we use a high entropy dopant (HED) approach to stabilise the highly conducting -Bi2O3 phase at much lower dopant levels than can be achieved using a single dopant allowing for significantly higher conductivities to be attained. This proposal seeks to clarify the oxide ion vacancy/interstitial distribution in three new HED stabilised bismuth oxides, with a view to correlating these structural changes with changes seen in the conductivity behaviour as a function of temperature.