Disorder-induced transition from grain boundary to bulk dominated ionic diffusion in pyrochlores

Nanoscale
Romain PerriotBlas P Uberuaga

Abstract

We use molecular dynamics simulations to investigate the role of grain boundaries (GBs) on ionic diffusion in pyrochlores, as a function of the GB type, chemistry of the compound, and level of cation disorder. We observe that the presence of GBs promotes oxygen transport in ordered and low-disordered systems, as the GBs are found to have a higher concentration of mobile carriers with higher mobilities than in the bulk. Thus, in ordered samples, the ionic diffusion is 2D, localized along the grain boundary. When cation disorder is introduced, bulk carriers begin to contribute to the overall diffusion, while the GB contribution is only slightly enhanced. In highly disordered samples, the diffusive behavior at the GBs is bulk-like, and the two contributions (bulk vs. GB) can no longer be distinguished. There is thus a transition from 2D/GB dominated oxygen diffusivity to 3D/bulk dominated diffusivity versus disorder in pyrochlores. These results provide new insights into the possibility of using internal interfaces to enhance ionic conductivity in nanostructured complex oxides.

References

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Sep 24, 2014·Nature Communications·Pratik P DholabhaiBlas P Uberuaga
Sep 30, 2014·Nanoscale·Veronika MetlenkoRoger A De Souza
Mar 10, 2015·Journal of the American Chemical Society·Dario MarrocchelliBilge Yildiz
Sep 2, 2015·Physical Chemistry Chemical Physics : PCCP·Blas Pedro Uberuaga, Romain Perriot
Nov 12, 2015·Scientific Reports·Dilpuneet S AidhyWilliam J Weber
Apr 29, 2016·ACS Applied Materials & Interfaces·Stephan P Waldow, Roger A De Souza
Nov 17, 2010·Science and Technology of Advanced Materials·Emiliana FabbriEnrico Traversa

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