La1-xBa1+xGaO4-0 (LBG) compounds, based on unconnected GaO4 moieties, were recently proposed as proton conductors. Protonic defects in the lattice are inserted through self-doping with Ba2+, to create oxygen vacancies subsequently filled by hydroxyl ions. We present a combined structural analysis on self-doped LBG using X-ray diffraction (XRD) and X-ray absorption (EXAFS): these results unravel the finer structural details on the short-range and long-range scales, and they are correlated with the dynamical properties of protonic conduction coming from vibrational spectroscopy. The structure of the GaO4 groups is independent of the oxide composition. On hydration, an array of short intertetrahedral hydrogen bonds is formed, producing a contraction of the a axis. On the basis of thermogravimetric analysis, EXAFS, XRD and infrared spectroscopy (IR) results, we propose that the stiffness of the GaO4 tetrahedra hinders the intratetrahedral proton transfer, while the noticeable fraction of protons involved in strong hydrogen bonds limit the proton reorientational freedom.

Giannici, F., Messana, D., Longo, A., Martorana, A. (2011). Crystal Structure and Local Dynamics in Tetrahedral Proton-Conducting La1-xBa1+xGaO4. JOURNAL OF PHYSICAL CHEMISTRY. C, 115, 298-304 [10.1021/jp1061896].

Crystal Structure and Local Dynamics in Tetrahedral Proton-Conducting La1-xBa1+xGaO4

GIANNICI, Francesco;MARTORANA, Antonino
2011-01-01

Abstract

La1-xBa1+xGaO4-0 (LBG) compounds, based on unconnected GaO4 moieties, were recently proposed as proton conductors. Protonic defects in the lattice are inserted through self-doping with Ba2+, to create oxygen vacancies subsequently filled by hydroxyl ions. We present a combined structural analysis on self-doped LBG using X-ray diffraction (XRD) and X-ray absorption (EXAFS): these results unravel the finer structural details on the short-range and long-range scales, and they are correlated with the dynamical properties of protonic conduction coming from vibrational spectroscopy. The structure of the GaO4 groups is independent of the oxide composition. On hydration, an array of short intertetrahedral hydrogen bonds is formed, producing a contraction of the a axis. On the basis of thermogravimetric analysis, EXAFS, XRD and infrared spectroscopy (IR) results, we propose that the stiffness of the GaO4 tetrahedra hinders the intratetrahedral proton transfer, while the noticeable fraction of protons involved in strong hydrogen bonds limit the proton reorientational freedom.
2011
Giannici, F., Messana, D., Longo, A., Martorana, A. (2011). Crystal Structure and Local Dynamics in Tetrahedral Proton-Conducting La1-xBa1+xGaO4. JOURNAL OF PHYSICAL CHEMISTRY. C, 115, 298-304 [10.1021/jp1061896].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/54751
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