Fast Ionic Transport Along Twin Walls in Ferroelastic Minerals
Ionic mobility is often enhanced for transport along grain boundaries when compared with bulk transport. Fine grained ceramics may show much faster transport than single crystals and, thus, observation of fast transport in the natural environment (e.g. mineral assemblies) could be conjectured to be intrinsically linked to grain boundary effects.1,2 This conjecture may not be correct for ferroelastic minerals, however. Such minerals undergo ferroelastic phase transitions which generate characteristic microstructures.3 Simple elements of ferroelastic microstructures are twin boundaries which often combine in order to form more complex patterns such as needles, combs, junctions and forks. In each case the local structural modification inside a twin wall is rather subtle because there are no topological defects present as in grain boundaries. The only changes are small variations of atomic bond distances and/or local changes of atomic ordering schemes. Despite the relative weakness of the structural perturbations, it was found that transport along ferroelastic twin boundaries can be strongly enhanced.
KeywordsDomain Wall Twin Boundary Fast Transport Twin Domain Fast Ionic Transport
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