H/D isotope effects in high temperature proton conductors

Bonanos, Nikolaos; Huijser, Annemarie; Poulsen, F.W.

doi:10.1016/j.ssi.2015.03.028

Cited by 51 publications

(42 citation statements)

References 28 publications

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“…This can be explained by the semiclassical model, which assumes that isotope exchange influences not only vibration frequencies, but also the zero-point energy in the potential well where the H and D species reside. The semiclassical model predicts a slight difference in activation energy, close to 0.054 eV 57 . Table 2 shows that in most cases the difference in the activation energies of total conductivities is 0.06 -0.09 eV.…”

Section: Discussionmentioning

confidence: 81%

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Influence of Sb-substitution on ionic transport in lanthanum orthoniobates

et al. 2016

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The results of ionic transport measurements for the lanthanum orthoniobate substituted with 10 and 30 mol% of antimony (LaNb0.9Sb0.1O4 and LaNb0.7Sb0.3O4) are presented and discussed. The influence of calcium co-doping on these properties has also been analysed. It has been shown that for the investigated material protonic conductivity predominates at temperatures up to 800 °C in oxidizing atmospheres, in wet conditions. Maximum observed protonic conductivity reaches ~10-4 S/cm at 800 °C (in humidified air); in the dry conditions the increasing influence of oxygen vacancies and holes is detected. Oxygen self-diffusivity has also been analysed by isotopic exchange to investigate the possible diffusion paths.

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Section: Discussionmentioning

confidence: 81%

“…As described in detail by Bonanos et.al. 57 the influence of isotope exchange can be analysed by . At lower temperatures the ratio between D2O and H2O is close to the predicted value indicating that protons dominate the transport properties of the materials.…”

Section: Discussionmentioning

confidence: 99%

Influence of Sb-substitution on ionic transport in lanthanum orthoniobates

et al. 2016

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“…56 † † This energy is obtained by subtracting to the PIMD energy the zero-point energies obtained in the harmonic approximation for the two bending modes, which are roughly orthogonal to the reaction coordinate. ** The H/D atom is considered as attached to an infinite mass, so that the ratio of the eigenpulsations from H to D is supposed to be exactly ffiffi ffi 2 p .…”

Section: Resultsmentioning

confidence: 99%

Proton transport in barium stannate: classical, semi-classical and quantum regimes

Geneste

Ottochian

Hermet

et al. 2015

Phys. Chem. Chem. Phys.

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Density-functional theory calculations are performed to investigate proton transport in BaSnO3. Structural optimizations in the stable and saddle point configurations for transfer (hopping) and reorientation allow description of the high-temperature classical and semi-classical regimes, in which diffusion occurs by over-barrier motion. At lower temperature (typically below 300 K), we describe the thermally-assisted quantum regime, in which protonic motion is of quantum nature and occurs in "coincidence" configurations favored by thermal fluctuations of the surrounding atoms. Both the non-adiabatic and the adiabatic limits are examined. In the adiabatic limit, the protonic energy landscape in the coincidence configuration is very flat. Path-integral molecular dynamics simulations of the proton in the coincidence potential reveal, in the transfer case, that the density of probability of H(+) has its maximum at the saddle point, because the zero-point energy exceeds the coincidence barrier. Arguments are given that support the adiabatic picture for the transfer mechanism. In the case of reorientation, the time scales for the existence of the coincidence and for protonic motion, as estimated from the time-energy uncertainty principle by using a simple one-dimensional model, are of the same order of magnitude, suggesting that the adiabatic limit is not reached. Protonic transfer and reorientation in this oxide are therefore governed by different mechanisms below room temperature.

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“…Assuming that isotope change does not affect concentration of charge carriers, conductivity ratio can be given as σH/σD ≈ √2. The pseudoclassic model allows to compute change of the energy of the basic state ΔE0 between proton and deuterium, which is 0.054 eV, and such difference of the activation energy of conductivity can be expected in the temperature range at which proton conductivity is dominant [22,23].…”

Section: Proton Transport In Perovskite-type Oxidesmentioning

confidence: 99%

Optimization of proton conductors for application in solid oxide fuel cell technology

Świerczek

Skubida

2017

E3S Web Conf.

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Abstract. Application of proton-conducting ceramic membranes in various electrochemical devices (e.g. SOFCs, SOECs) is considered as highly beneficial. Because of a unique transport mechanism associated with proton movement in oxide materials, designing and optimization, as well as practical application of such proton conductors is a challenge. In this work, apart from discussion of literature data, authors' own results are provided, which are focused on material-related issues, including development of electrolyte and electrode materials exhibiting high proton conductivity.

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H/D isotope effects in high temperature proton conductors

Cited by 51 publications

References 28 publications

Influence of Sb-substitution on ionic transport in lanthanum orthoniobates

Influence of Sb-substitution on ionic transport in lanthanum orthoniobates

Proton transport in barium stannate: classical, semi-classical and quantum regimes

Optimization of proton conductors for application in solid oxide fuel cell technology

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