Prediction of oxygen ion conduction from relative Coulomb electronic interactions in oxyapatites

Abstract

In order to offer a guideline to search for new oxyapatites exhibiting high ionic conductivities (s) for possible application in solid oxide fuel cells operating at intermediate temperatures (IT-SOFCs), a mathematical model is developed, i.e., a linear relation of s and the relative Coulomb energy, to predict the s of oxyapatites. The inputs to the model are two readily available elemental properties, namely the ionic radius and the electronegativity of the constituent elements. The model not only predicts the ionic conductivities of 45 oxyapatites but also rationalizes the observed trends reported in the literatures. The effects of the two elemental properties on ionic conductivity are also examine and predict a wide range of new oxygen stoichiometric oxyapatites with ionic conductivities potentially as high as 10 -2 -10 -1 S cm -1 at 500 °C is predicted. The investigations suggests an optimization strategy to search for promising oxyapatites, i.e., applying dopants with large ionic radii and low electronegativities. © 2011 Elsevier B.V. All rights reserved.