Probing Cation and Vacancy Ordering in the Dry and Hydrated Yttrium-Substituted BaSnO<sub>3</sub> Perovskite by NMR Spectroscopy and First Principles Calculations: Implications for Proton Mobility

Buannic, Lucienne; Blanc, Frédéric; Middlemiss, Derek S.; Grey, Clare P.

doi:10.1021/ja304712v

Cited by 48 publications

(56 citation statements)

References 52 publications

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“…In this work, we use DFT+U , with U applied on the p states of oxygen, to describe the self-trapped state, the trapping effect of dopants and the mobility of holes, in the case of barium stannate, BaSnO 3 (BSO), a potential electrolyte material for SOFCs and PCFCs [19][20][21][22][23][24][25][26][27][28], for which hole-type conductivity at high temperature has been reported [20,27,28]. Besides, we propose a slightly modified DFT+U scheme, more adapted to p orbitals, and show that such scheme is able to provide similar physics, but with more physical values of U than the ones traditionally used in the literature.…”

Section: ••mentioning

confidence: 99%

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

et al. 2017

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The charge-transfer insulating perovskite oxides currently used as fuel cell electrolytes undergo, at high temperature, an oxidation reaction• , that produces oxygen-type holes. Understanding the nature and mobility of these oxygen-type holes is an important step to improve the performance of devices, but presents a theoretical challenge since, in their localized form, they cannot be captured by standard density functional theory. Here, we employ the DFT+U formalism with a Hubbard correction on the p orbitals of oxygen to investigate several properties of these holes, in the particular case of BaSnO 3 . We describe the small oxygen-type hole polarons, the self-trapping at their origin, and their trapping by trivalent dopants (Ga, Sc, In, Lu, Y, Gd, La). Strong similarities with protonic defects are observed concerning the evolution of the trapping energy with ionic radius of the dopant. Moreover, we show that long-range diffusion of holes is a complex phenomenon, that proceeds by a succession of several mechanisms. However, the standard implementation of DFT+U within the projector augmented-wave (PAW) formalism leads to use very large, unphysical values of U for the O-p orbital. We propose here a slightly modified DFT+U scheme, that takes into account the fact that the O-p is truncated in usual DFT+U implementation in PAW. This scheme yields more physical values of U than the ones traditionally used in the literature, and describes well the properties of the hole polaron.

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Section: ••mentioning

confidence: 99%

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

et al. 2017

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“…Experimental evidence for the vacancy being close to the dopant ion is available for yttrium doped BaZrO 3 [41] and for BaZr 1-x Sc x O 3- [42].…”

Section: I) Role Of Yttrium Dopant and Oxygen Vacancies On The Crystamentioning

confidence: 99%

Thermal evolution of the crystal structure of proton conducting BaCe_0.8Y_0.2O_3−δ from high-resolution neutron diffraction in dry and humid atmosphere

et al. 2015

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The crystal structure of the proton conducting perovskite BaCe(0.8)Y(0.2)O(3-δ) (BCY20) has been studied via high-resolution in situ neutron diffraction performed in controlled dry and humid (heavy water) oxygen flow. Two phase transitions, cubic Pm3[combining macron]m→R3[combining macron]c (775 °C)→Imma (250 °C) were observed on cooling from 1000 °C in dry O(2). A significant shift of the phase stability fields was observed on cooling in wet oxygen (pD(2)O ≈ 0.2 atm) with the R3[combining macron]c structure stabilised at 900 °C, and the R3[combining macron]c→Imma transition occurring at 675 °C. On cooling below 400 °C a monoclinic, I2/m, phase started to appear. The structural dependence on hydration level is primarily due to the de-stabilisation of the correlated, octahedra tilts as a consequence of structural relaxation around the oxygen vacancies present in the non-hydrated phase. The tendency of hydrated BaCe(0.8)Y(0.2)O(3-δ) to show octahedral tilting is also found to be enhanced, indicating that the deuteronic (protonic) defects influence the crystal structure, possibly via hydrogen bonding. Stabilisation of the monoclinic I2/m phase is attributed to the structural effect of deuterons that is inferred to increase on cooling as deuterons localise to a greater extent. Changing from wet oxidising (O(2) + D2O(g)) to wet reducing (5% H2 in Ar + D2O(g)) atmosphere did not influence the structure or the phase stability, indicating that Ce(4+) was not reduced under the present conditions. Based on the observed cell volume expansion protonic defects are present in the material at 900 °C at a D(2)O partial pressure of ∼0.2 atm. The origin of the chemical expansion is explained by the effective size of the oxygen vacancy being significantly smaller than the [OD] defect. Rietveld analysis has been used to locate possible sites for the deuterons in the high temperature, R3[combining macron]c and Imma, phases that are most relevant for proton transport.

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“…[10][11][12][13][14] This combines a plane-wave basis set with the total energy pseudo-potential method and is ideal for periodic systems. The…”

Section: Energetics and Configurationsmentioning

confidence: 99%

Dynamic Nuclear Polarization NMR of Low-γ Nuclei: Structural Insights into Hydrated Yttrium-Doped BaZrO₃

Blanc

Sperrin

Lee

et al. 2014

J. Phys. Chem. Lett.

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We demonstrate that solid-state NMR spectra of challenging nuclei with a low gyromagnetic ratio such as yttrium-89 can be acquired quickly with indirect dynamic nuclear polarization (DNP) methods. Proton to 89Y cross polarization (CP) magic angle spinning (MAS) spectra of Y3+ in a frozen aqueous solution were acquired in minutes using the AMUPol biradical as a polarizing agent. Subsequently, the detection of the 89Y and 1H NMR signals from technologically important hydrated yttrium-doped zirconate ceramics, in combination with DFT calculations, allows the local yttrium and proton environments present in these protonic conductors to be detected and assigned to different hydrogen-bonded environments.

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Probing Cation and Vacancy Ordering in the Dry and Hydrated Yttrium-Substituted BaSnO₃ Perovskite by NMR Spectroscopy and First Principles Calculations: Implications for Proton Mobility

Cited by 48 publications

References 52 publications

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

Thermal evolution of the crystal structure of proton conducting BaCe_0.8Y_0.2O_3−δ from high-resolution neutron diffraction in dry and humid atmosphere

Dynamic Nuclear Polarization NMR of Low-γ Nuclei: Structural Insights into Hydrated Yttrium-Doped BaZrO₃

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Probing Cation and Vacancy Ordering in the Dry and Hydrated Yttrium-Substituted BaSnO3 Perovskite by NMR Spectroscopy and First Principles Calculations: Implications for Proton Mobility

Cited by 48 publications

References 52 publications

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

DFT+ U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

Thermal evolution of the crystal structure of proton conducting BaCe0.8Y0.2O3−δ from high-resolution neutron diffraction in dry and humid atmosphere

Dynamic Nuclear Polarization NMR of Low-γ Nuclei: Structural Insights into Hydrated Yttrium-Doped BaZrO3

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Product

Resources

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Probing Cation and Vacancy Ordering in the Dry and Hydrated Yttrium-Substituted BaSnO₃ Perovskite by NMR Spectroscopy and First Principles Calculations: Implications for Proton Mobility

Thermal evolution of the crystal structure of proton conducting BaCe_0.8Y_0.2O_3−δ from high-resolution neutron diffraction in dry and humid atmosphere

Dynamic Nuclear Polarization NMR of Low-γ Nuclei: Structural Insights into Hydrated Yttrium-Doped BaZrO₃