How Proton Incorporation Reshapes Lattice Dynamics In BaSnO3-Type Proton Conductors

Artur Braun; Alexey Rulev; Nobumoto Nagasawa; Hongxin Wang; Tatyana Bendikov; Vladimir Pomjakushin; Martin Kunz; Yoshitaka Yoda; Qianli Chen; Stephen P. Cramer

doi:10.1002/advs.76065

How Proton Incorporation Reshapes Lattice Dynamics In BaSnO₃-Type Proton Conductors

Artur Braun^*
, Alexey Rulev
, Nobumoto Nagasawa
, Hongxin Wang
, Tatyana Bendikov
, Vladimir Pomjakushin
, Martin Kunz
, Yoshitaka Yoda
, Qianli Chen
, Stephen P. Cramer

^*Corresponding author for this work

Department of Chemical Research Support

Research output: Contribution to journal › Article › peer-review

Abstract

Proton conduction in acceptor-doped perovskites is fundamentally a vibronic process: mobile (Formula presented.) and (Formula presented.) do not move independently, but dynamically co-vibrate with the surrounding oxygen–metal framework. Direct experimental evidence for this behavior is presented using in situ (Formula presented.) nuclear resonance vibrational spectroscopy (NRVS) on hydrated, deuterated, and dry (Formula presented.). Hydration induces systematic redistributions in the Sn-projected phonon density of states (PDOS), including an upshift of the first spectral moment by about 0.4 meV, indicating a stiffening of the extended Sn–O network. H/D isotopic substitution leaves the Sn-projected PDOS largely unchanged, with only subtle isotope-dependent spectral reweighting, demonstrating that protonic degrees of freedom are not localized oscillators but are embedded in collective lattice modes. These results are rationalized using a classical coupled proton–phonon oscillator model that links the observed PDOS variations to changes in effective force constants and vibrational mass terms. The model captures how (Formula presented.) and (Formula presented.) participate in cooperative lattice dynamics rather than forming isolated OH/OD entities. Overall, NRVS probes proton–lattice coupling in ceramic proton conductors and quantitatively describes how protonic defects modulate host lattice dynamics to enable phonon-assisted long-range proton transport.

Original language	English
Article number	e76065
Number of pages	9
Journal	Advanced Science
Volume	13
Issue number	50
DOIs	https://doi.org/10.1002/advs.76065
Publication status	Published Online - 15 Jun 2026

Funding

A.B. acknowledges financial support from the Swiss National Science Foundation through projects 188588, 232511, beamtime by SPring-8 BL35XU (Japan) for NRVS experiments (proposal numbers 2022A1406, 2023B1095, 2024B1486), SINQ proposal number 20230277 and ALS Director's Discretion beamtime granted under number DD-737. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Beamline 12.2.2 benefits from the support of SEES (Synchrotron Earth and Environmental Science):SEES is supported by the National Science Foundation Division of Earth Sciences (EAR) SEES: Synchrotron Earth and Environmental Science (EAR -2223273). S.P.C. and H.W. acknowledge financial support from (NIH) GM65440. We are grateful to Dr. Daniel Rentsch (Empa Functional Polymers) for NMR analysis of the 119Sn$<^>{119}{ m Sn}$ isotope metal and to Dr. Fanni Juranyi (PSI, SINQ) for support at the FOCUS beamline.

All Science Journal Classification (ASJC) codes

Medicine (miscellaneous)
General Chemical Engineering
Biochemistry, Genetics and Molecular Biology (miscellaneous)
General Materials Science
General Engineering
General Physics and Astronomy

Access to Document

10.1002/advs.76065Licence: CC BY

Cite this

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title = "How Proton Incorporation Reshapes Lattice Dynamics In BaSnO3-Type Proton Conductors",

abstract = "Proton conduction in acceptor-doped perovskites is fundamentally a vibronic process: mobile (Formula presented.) and (Formula presented.) do not move independently, but dynamically co-vibrate with the surrounding oxygen{\textendash}metal framework. Direct experimental evidence for this behavior is presented using in situ (Formula presented.) nuclear resonance vibrational spectroscopy (NRVS) on hydrated, deuterated, and dry (Formula presented.). Hydration induces systematic redistributions in the Sn-projected phonon density of states (PDOS), including an upshift of the first spectral moment by about 0.4 meV, indicating a stiffening of the extended Sn{\textendash}O network. H/D isotopic substitution leaves the Sn-projected PDOS largely unchanged, with only subtle isotope-dependent spectral reweighting, demonstrating that protonic degrees of freedom are not localized oscillators but are embedded in collective lattice modes. These results are rationalized using a classical coupled proton{\textendash}phonon oscillator model that links the observed PDOS variations to changes in effective force constants and vibrational mass terms. The model captures how (Formula presented.) and (Formula presented.) participate in cooperative lattice dynamics rather than forming isolated OH/OD entities. Overall, NRVS probes proton{\textendash}lattice coupling in ceramic proton conductors and quantitatively describes how protonic defects modulate host lattice dynamics to enable phonon-assisted long-range proton transport.",

author = "Artur Braun and Alexey Rulev and Nobumoto Nagasawa and Hongxin Wang and Tatyana Bendikov and Vladimir Pomjakushin and Martin Kunz and Yoshitaka Yoda and Qianli Chen and Cramer, \{Stephen P.\}",

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AU - Braun, Artur

AU - Rulev, Alexey

AU - Nagasawa, Nobumoto

AU - Wang, Hongxin

AU - Bendikov, Tatyana

AU - Pomjakushin, Vladimir

AU - Kunz, Martin

AU - Yoda, Yoshitaka

AU - Chen, Qianli

AU - Cramer, Stephen P.

PY - 2026/6/15

Y1 - 2026/6/15

N2 - Proton conduction in acceptor-doped perovskites is fundamentally a vibronic process: mobile (Formula presented.) and (Formula presented.) do not move independently, but dynamically co-vibrate with the surrounding oxygen–metal framework. Direct experimental evidence for this behavior is presented using in situ (Formula presented.) nuclear resonance vibrational spectroscopy (NRVS) on hydrated, deuterated, and dry (Formula presented.). Hydration induces systematic redistributions in the Sn-projected phonon density of states (PDOS), including an upshift of the first spectral moment by about 0.4 meV, indicating a stiffening of the extended Sn–O network. H/D isotopic substitution leaves the Sn-projected PDOS largely unchanged, with only subtle isotope-dependent spectral reweighting, demonstrating that protonic degrees of freedom are not localized oscillators but are embedded in collective lattice modes. These results are rationalized using a classical coupled proton–phonon oscillator model that links the observed PDOS variations to changes in effective force constants and vibrational mass terms. The model captures how (Formula presented.) and (Formula presented.) participate in cooperative lattice dynamics rather than forming isolated OH/OD entities. Overall, NRVS probes proton–lattice coupling in ceramic proton conductors and quantitatively describes how protonic defects modulate host lattice dynamics to enable phonon-assisted long-range proton transport.

AB - Proton conduction in acceptor-doped perovskites is fundamentally a vibronic process: mobile (Formula presented.) and (Formula presented.) do not move independently, but dynamically co-vibrate with the surrounding oxygen–metal framework. Direct experimental evidence for this behavior is presented using in situ (Formula presented.) nuclear resonance vibrational spectroscopy (NRVS) on hydrated, deuterated, and dry (Formula presented.). Hydration induces systematic redistributions in the Sn-projected phonon density of states (PDOS), including an upshift of the first spectral moment by about 0.4 meV, indicating a stiffening of the extended Sn–O network. H/D isotopic substitution leaves the Sn-projected PDOS largely unchanged, with only subtle isotope-dependent spectral reweighting, demonstrating that protonic degrees of freedom are not localized oscillators but are embedded in collective lattice modes. These results are rationalized using a classical coupled proton–phonon oscillator model that links the observed PDOS variations to changes in effective force constants and vibrational mass terms. The model captures how (Formula presented.) and (Formula presented.) participate in cooperative lattice dynamics rather than forming isolated OH/OD entities. Overall, NRVS probes proton–lattice coupling in ceramic proton conductors and quantitatively describes how protonic defects modulate host lattice dynamics to enable phonon-assisted long-range proton transport.

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