Proton trapping in yttrium-doped barium zirconate

Yamazaki, Yoshihiro; Blanc, Frédéric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan; Grey, Clare P.; Haile, Sossina M.

doi:10.1038/nmat3638

Cited by 331 publications

(406 citation statements)

References 27 publications

(5 reference statements)

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“…For the undoped system, i.e., without proton‐trapping effect, our simulations predict E A = (0.18 ± 0.02) eV, in agreement with previous simulations19, 44 and with the experimental E A for trap‐free migration 18. For the doped system, however, a bending in the Arrhenius plot is observed ( Figure 6 ).…”

Section: Resultssupporting

confidence: 91%

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Enhanced Proton Conductivity in Y‐Doped BaZrO₃ via Strain Engineering

et al. 2017

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The effects of stress‐induced lattice distortions (strain) on the conductivity of Y‐doped BaZrO3, a high‐temperature proton conductor with key technological applications for sustainable electrochemical energy conversion, are studied. Highly ordered epitaxial thin films are grown in different strain states while monitoring the stress generation and evolution in situ. Enhanced proton conductivity due to lower activation energies is discovered under controlled conditions of tensile strain. In particular, a twofold increased conductivity is measured at 200 °C along a 0.7% tensile strained lattice. This is at variance with conclusions coming from force‐field simulations or the static calculations of diffusion barriers. Here, extensive first‐principles molecular dynamic simulations of proton diffusivity in the proton‐trapping regime are therefore performed and found to agree with the experiments. The simulations highlight that compressive strain confines protons in planes parallel to the substrate, while tensile strain boosts diffusivity in the perpendicular direction, with the net result that the overall conductivity is enhanced. It is indeed the presence of the dopant and the proton‐trapping effect that makes tensile strain favorable for proton conduction.

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Section: Resultssupporting

confidence: 91%

“…Therefore, the proton‐dopant association energy largely contributes to the total effective E A , which has been suggested to be as low as about 0.15 eV in an ideal trap‐free BaZrO 3 physicochemical environment . 18, 19 …”

Section: Introductionmentioning

confidence: 99%

Enhanced Proton Conductivity in Y‐Doped BaZrO₃ via Strain Engineering

et al. 2017

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“…This stands in contrast to the prevailing view that each oxygen vacancy is charge compensated by two Ce 3 þ defects. It appears that the OH O saturating the oxygen vacancies is effectively a positively charged defect, which is then charge compensated by Ce 3 þ , similar to the bulk of proton-conducting oxides 51 . Next, we turn to the rate at which small polarons migrate from the bulk to the surface during WSR, and vice versa during HOR.…”

Section: Resultsmentioning

confidence: 98%

“…We note that the lack of change in the electrostatic potential profile, despite the significant change in the OH O concentration, could be because of the preservation of charge neutrality (as observed in the bulk of proton-conducting oxides like doped BaZrO 3 (ref. 51). It may also relate to the high concentration of near-surface mobile charge carriers available to screen the excess charge.…”

Section: Resultsmentioning

confidence: 99%

Fast vacancy-mediated oxygen ion incorporation across the ceria–gas electrochemical interface

et al. 2014

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Electrochemical incorporation reactions are ubiquitous in energy storage and conversion devices based on mixed ionic and electronic conductors, such as lithium-ion batteries, solidoxide fuel cells and water-splitting membranes. The two-way traffic of ions and electrons across the electrochemical interface, coupled with the bulk transport of mass and charge, has been challenging to understand. Here we report an investigation of the oxygen-ion incorporation pathway in CeO 2-d (ceria), one of the most recognized oxygen-deficient compounds, during hydrogen oxidation and water splitting. We probe the response of surface oxygen vacancies, electrons and adsorbates to the electrochemical polarization at the ceria-gas interface. We show that surface oxygen-ion transfer, mediated by oxygen vacancies, is fast. Furthermore, we infer that the electron transfer between cerium cations and hydroxyl ions is the rate-determining step. Our in operando observations reveal the precise roles of surface oxygen vacancy and electron defects in determining the rate of surface incorporation reactions.

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“…associates an effective -1 charge and protons being positively charged, they make defect association. Protons are said to be trapped by dopants and state of protons become more ordered [16]. The defect pairs (Y-H) act as electric dipoles.…”

Section: Electrical Properties Of Bczymentioning

confidence: 99%