Linking Nanoscale Grain Boundary Composition and Energetic Properties in Ceramic Oxides*

Ceramic oxides are used for a wide variety of technologically relevant applications from electrochemical devices, novel resistive switching devices and oxygen sensors. Applications such as these typically rely upon the ability of oxides to conduct ions efficiently through the lattice. Recent nanoscale compositional characterization of the GB composition has shown different nominal concentrations of solutes could result in orders of magnitude increase in GB ionic conductivity relative to the undoped samples. This study aims to predict the optimal dopants that, when present in high concentrations, increase the ionic conductivity across the GB. Computational modeling is employed using density functional theory to optimize the GB interfacial structure for various GB misorientations in CeO2. This study further develops our understanding of high solute GB composition enabling the development of methods such as selective doping to improve macroscopic ionic conductivity for both the grain and GB.