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Paving the way to nanoionics [electronic resource] : Atomic origin of barriers for ionic transport through interfaces

Published:
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:
Article numbers 17,229 : digital, PDF file
Additional Creators:
Oak Ridge National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
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. In conclusion, 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.
Report Numbers:
E 1.99:1259714
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Note:
Published through SciTech Connect.
12/17/2015.
"srep17229"
Scientific Reports 5 ISSN 2045-2322 AM
M. A. Frechero; M. Rocci; G. Sanchez-Santolino; Amit Kumar; J. Salafranca; Rainer Schmidt; M. R. Diaz-Guillen; O. J. Dura; A. Rivera-Calzada; R. Mishra; Stephen Jesse; S. T. Pantelides; Sergei V. Kalinin; M. Varela; S. J. Pennycook; J. Santamaria; C. Leon.
Funding Information:
MAT2011-27470-C01
S2009/MAT-1756
239739
View MARC record | catkey: 23758995