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We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at non-integer Li concentrations, while ordered phases explain regions of sharply lower conductivity. Disorder is therefore predicted to be optimal for ionic transport in this and other conductor families with strong Li interaction.

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Climb creep provides an efficient deformation mechanism for bridgmanite under lower mantle conditions.

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We performed molecular dynamics simulations of silicon nanostructures submitted to various stresses and temperatures. For a given stress orientation, a transition in the onset of silicon plasticity is revealed depending on the temperature and stress magnitude. At high temperature and low stress, partial dislocation loops are nucleated in the {111} glide set planes. But at low temperature and very high stress, perfect dislocation loops are formed in the other set of {111} planes called shuffle. This result confirmed by three different classical potentials suggests that plasticity in silicon nanostructures could be controlled by dislocation nucleation.