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

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 grainmore » boundary.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [2] ;  [2] ;  [2] ;  [2] ;  [5] ;  [4] ;  [5] ;  [4] ;  [3] ;  [6] ;  [2] ;  [2]
  1. Univ. Complutense de Madrid, Madrid (Spain); Univ. Nacional del Sur, Bahia Blanca, (Argentina)
  2. Univ. Complutense de Madrid, Madrid (Spain)
  3. Univ. Complutense de Madrid, Madrid (Spain); Materials Science & Technology Div., Oak Ridge, TN (United States)
  4. Center for Nanophase Materials Sciences, Oak Ridge, TN (United States)
  5. Materials Science & Technology Div., Oak Ridge, TN (United States); Vanderbilt Univ., Nashville, TN (United States)
  6. The Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
MAT2011-27470-C01; S2009/MAT-1756; 239739
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; fuel cells; surfaces, interfaces and thin films
OSTI Identifier: