Title: YSZ thin films with minimized grain boundary resistivity

Abstract

In recent years, interface engineering of solid electrolytes has been explored to increase their ionic conductivity and improve the performance of solid oxide fuel cells and other electrochemical power sources. It has been observed that the ionic conductivity of epitaxially grown thin films of some electrolytes is dramatically enhanced, which is often attributed to effects (e.g. strain-induced mobility changes) at the heterophase boundary with the substrate. Still largely unexplored is the possibility of manipulation of grain boundary resistivity in polycrystalline solid electrolyte films, clearly a limiting factor in their ionic conductivity. Here in this paper, we report that the ionic conductivity of yttria stabilized zirconia thin films with nano-columnar grains grown on a MgO substrate nearly reaches that of the corresponding single crystal when the thickness of the films becomes less than roughly 8 nm (smaller by a factor of three at 500 °C). Using impedance spectroscopy, the grain boundary resistivity was probed as a function of film thickness. The resistivity of the grain boundaries near the film–substrate interface and film surface (within 4 nm of each) was almost entirely eliminated. This minimization of grain boundary resistivity is attributed to Mg²⁺ diffusion from the MgO substrate into the YSZ grainmore » boundaries, which is supported by time of flight secondary ion mass spectroscopy measurements. We suggest grain boundary “design” as an attractive method to obtain highly conductive solid electrolyte thin films.« less

Authors:

Mills, Edmund M. ^[1]; Kleine-Boymann, Matthias ^[2]; Janek, Juergen ^[2]; Yang, Hao ^[3]; Browning, Nigel D. ^[3]; Takamura, Yayoi ^[1]; Kim, Sangtae ^[1]

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+ Show Author Affiliations

1. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
2. Justus-Liebig-Univ. Gießen, Gießen (Germany). Physikalisch-Chemisches Inst.
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Publication Date:

Thu Mar 31 00:00:00 EDT 2016

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Sponsoring Org.:

National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1418491

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Accepted Manuscript

Journal Name:

Physical Chemistry Chemical Physics. PCCP

Additional Journal Information:

Journal Volume: 18; Journal Issue: 15; Journal ID: ISSN 1463-9076

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE