Quantification of grain boundary defect chemistry in a mixed proton‐electron conducting oxide composite

Abstract

Dual phase oxide membranes have shown promising hydrogen permeation fluxes in syngas applications due to their high mixed proton electron conduction (MPEC). However, the conductivity of grain boundaries can be many orders of magnitude lower than that of the bulk and so limits the total conductivity and hydrogen permeation. In this study, the three‐dimensional nanoscale oxygen and cation distributions around grain and phase boundaries in a BaCe0.8Y0.2O3‐δ‐Ce0.8Y0.2O2‐δ (BCY‐YDC) membrane were quantified by atom probe tomography (APT) and related to average grain boundary conductivity measured by electrochemical impedance spectroscopy (EIS). Segregation varied among the general high‐angle grain boundaries analyzed, but no trend from orientation analysis was determined. Correlative APT and electron energy loss spectroscopy (EELS) of one YDC grain boundary revealed composition and cerium valence information, respectively, allowing for the determination of vacancies at the grain boundary. While a specific MPEC membrane is characterized, the results are relevant to proton and electron conduction in a number of technologically important ceramics.

Understanding the effects of fabrication process on BaZr0.9Y0.1O3−δ grain-boundary chemistry using atom probe tomography

“…However, in the future, we suggest that the combination of in situ TEM measurements of GB orientation combined with APT analysis of GB chemistry could provide further insight into potential GB structure-chemistry correlations in these materials. 47…”

A Review of Grain Boundary and Heterointerface Characterization in Polycrystalline Oxides by (Scanning) Transmission Electron Microscopy

“…However, data reconstruction can be a limiting factor, as it can potentially create artifacts [81]. APT has been coupled with STEM imaging and spectroscopy to provide a complementary understanding of GB structure and chemistry in Hf and La doped-alumina and Y-doped ceria [82,83]. Just like S/TEM, extensive optimization of specimens is necessary to obtain reliable APT results [84].…”

Integrative Atom Probe Tomography Using Scanning Transmission Electron Microscopy-Centric Atom Placement as a Step Toward Atomic-Scale Tomography

“…Similarly, electron diffraction patterns of the specimen volume acquired at 410 mm at 200 keV and using 4k × 4k image resolution result in average atomic spacings measurable to 0.05 ± 0.003 nm. Although only a single diffraction pattern was required for this epitaxial material system, modern 4D STEM diffraction techniques could certainly resolve a polycrystalline or heterostructural specimen (Burton et al, 2020a(Burton et al, , 2020bOphus, 2019).…”