Obtaining a better understanding of activation volumes in ionic conductors

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Superionic conductors are materials that provide fast ion conduction similar to liquid electrolytes, and are currently investigated for the use in solid-state batteries. Superionic conductors are usually investigated by temperature – dependent measurements with the goal to assess the activation energies and energetic barriers for the ionic jump. Whereas this approach has been successful in obtaining general characteristics of ion transport, the underlying structural phenomena of an ion jump are not well understood.In contrast, measuring the pressure – dependence of the ionic conductivity leads to another thermodynamic parameter, the activation volume. The activation volume describes how much a structure needs to distort locally to let an ion jump occur. However, while this thermodynamic property is known in general, an in depth understanding and description is missing in how a crystal structure and induced structural changes may affect the activation volume. Therefore, the proposal seeks to obtain a better fundamental understanding of the pressure – dependence of superionic conductors and the interplay between crystal structure and the activation volume.