Enhanced Proton Conductivity in Y‐Doped BaZrO₃ via Strain Engineering

Abstract

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.

Doping in garnet-type electrolytes: Kinetic and thermodynamic effects from molecular dynamics simulations

“…We achieve this despite some discrepancies observed during the direct comparison of the activation energies of the doped systems with experimental data [24,25]. In addition, when considering the nature of the defects induced by the hypervalent dopants (W centers in the explicit model), the additional coulombic repulsion promotes further scattering of the Li ions, causing an overall decrease of the conductivity and an increase of the activation energy, similar to the proton trapping effect in hydrogen conductors [53,54]. This is also evident from the analysis of the Li ions distribution around the dopants, which shows a depletion after the first coordination shell associated with the breaking of the Li "wire" (Fig.…”

Detrimental Effect of Sintering Additives on Conducting Ceramics: Yttrium‐Doped Barium Zirconate

“…[52] However,s uch ah ypothesis needs further investigation in the future. The reason is not clear,b ut one hypothesis is that in the reducing atmosphere, in addition to the removal of the copper metal, some of the copperc ations might be reduced to al ower valences state, such as from Cu II to Cu I ,r esulting in al ocal lattice expansion surroundingt hese copperc ationsb ecauseg enerally,t ensional stress on barium zirconate benefits the protonc onduc-tion.…”

Simulating Diffusion Properties of Solid‐State Electrolytes via a Neural Network Potential: Performance and Training Scheme

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