Paving the way to nanoionics: atomic origin of barriers for ionic transport through interfaces

Frechero, M. A; Rocci, Mirko; Sánchez Santolino, G; Kumar, Amit; Salafranca, J; Schmidt, Rainer; Díaz Guillén, M. R; Durá, O. J; Rivera Calzada, A; Mishra, R; Jesse, Stephen; Pantelides, S. T; Kalinin, Sergei V; Varela, M; Pennycook, S. J; Santamaria, J; Leon, C.

doi:10.1038/srep17229

The blocking of ion transport at interfaces strongly limits the performance of electrochemical nanodevices for energy applications. The barrier is believed to arise from space-charge regions generated by mobile ions by analogy to semiconductor junctions. Here we show that something different is at play by studying ion transport in a bicrystal of yttria (9% mol) stabilized zirconia (YSZ), an emblematic oxide ion conductor. Aberration-corrected scanning transmission electron microscopy (STEM) provides structure and composition at atomic resolution, with the sensitivity to directly reveal the oxygen ion profile. We find that Y segregates to the grain boundary at Zr sites, together with a depletion of oxygen that is confined to a small length scale of around 0.5 nm. Contrary to the main thesis of the space-charge model, there exists no evidence of a long-range O vacancy depletion layer. Combining ion transport measurements across a single grain boundary by nanoscale electrochemical strain microscopy (ESM), broadband dielectric spectroscopy measurements, and density functional calculations, we show that grain-boundary-induced electronic states act as acceptors, resulting in a negatively charged core. Besides the possible effect of the modified chemical bonding, this negative charge gives rise to an additional barrier for ion transport at the grain boundary.

Titolo:	Paving the way to nanoionics: atomic origin of barriers for ionic transport through interfaces
Autori:	Frechero, M. A ROCCI, MIRKO Sánchez Santolino, G Kumar, Amit Salafranca, J Schmidt, Rainer Díaz Guillén, M. R Durá, O. J Rivera Calzada, A Mishra, R Jesse, Stephen Pantelides, S. T Kalinin, Sergei V Varela, M Pennycook, S. J Santamaria, J Leon, C. mostra contributor esterni nascondi contributor esterni
Data di pubblicazione:	2015
Rivista:	SCIENTIFIC REPORTS
Digital Object Identifier (DOI):	http://dx.doi.org/10.1038/srep17229
Handle:	http://hdl.handle.net/11384/61485
Appare nelle tipologie:	1.1 Articolo in rivista

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http://hdl.handle.net/11384/61485

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