Quadrupolar NMR of Ionic Conductors, Batteries, and Other Energy-related Materials

Blanc, Frédéric; Spencer, Leigh; Goward, Gillian R.

doi:10.1002/9780470034590.emrstm1215

Cited by 5 publications

(17 citation statements)

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“…Unlike conventional diffraction-based methods sensitive to long-range order, solid-state NMR spectroscopy can provide insight into local, atomic-scale distortions in solids, with direct relevance to ionic conduction. − Moreover, exchange rates and activation energies for thermally activated transport processes can be derived from NMR spectra acquired at variable temperature (VT-NMR). Our group − and others − have shown that solid-state 17 O VT-NMR in particular can enable detailed mechanistic studies of fast oxide-ion conductors, subject to successful enrichment , of samples with 17 O (natural abundance 0.037%).…”

Section: Introductionmentioning

confidence: 99%

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy

et al. 2016

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While solid-state NMR spectroscopic techniques have helped clarify the local structure and dynamics of ionic conductors, similar studies of mixed ionic–electronic conductors (MIECs) have been hampered by the paramagnetic behavior of these systems. Here we report high-resolution 17O (I = 5/2) solid-state NMR spectra of the mixed-conducting solid oxide fuel cell (SOFC) cathode material La2NiO4+δ, a paramagnetic transition-metal oxide. Three distinct oxygen environments (equatorial, axial, and interstitial) can be assigned on the basis of hyperfine (Fermi contact) shifts and quadrupolar nutation behavior, aided by results from periodic DFT calculations. Distinct structural distortions among the axial sites, arising from the nonstoichiometric incorporation of interstitial oxygen, can be resolved by advanced magic angle turning and phase-adjusted sideband separation (MATPASS) NMR experiments. Finally, variable-temperature spectra reveal the onset of rapid interstitial oxide motion and exchange with axial sites at ∼130 °C, associated with the reported orthorhombic-to-tetragonal phase transition of La2NiO4+δ. From the variable-temperature spectra, we develop a model of oxide-ion dynamics on the spectral time scale that accounts for motional differences of all distinct oxygen sites. Though we treat La2NiO4+δ as a model system for a combined paramagnetic 17O NMR and DFT methodology, the approach presented herein should prove applicable to MIECs and other functionally important paramagnetic oxides.

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Section: Introductionmentioning

confidence: 99%

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy

et al. 2016

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“…The study of dynamics using NMR spectroscopy has been shown in a wide range of oxides and ceramics, and despite the added difficulties associated with studying quadrupolar nuclei,17 O NMR spectroscopy has provided particularly useful insight [4,94,[107][108][109] This can be demonstrated by recent work on ZrW Variable-temperature (28-229 ºC) 17 O MAS NMR spectra of 17 O-enriched ZrW 2 O 8 , shown inFigure 13a, suggest that all oxygen sites are involved in some sort of exchange at high temperature (i.e., above 175 °C), with the four resolved peaks seen at low temperatures coalescing as the temperature is increased. At lower temperatures line broadening of all four peaks also suggests some motion is present, but it is not possible to determine which sites are in exchange from the MAS spectra alone.…”

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Exploiting NMR spectroscopy for the study of disorder in solids

Moran

Dawson

Ashbrook

2017

International Reviews in Physical Chemistry

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Although the solid state is typically characterised by inherent periodicity, many interesting physical and chemical properties of solids arise from a variation in this, i.e., changes in the nature of the atom occupying a particular site in a crystal structure or variation in the position of an atom (or group of atoms) in different parts of a structure, or variation as a function of time. This lack of long-range order poses significant challenges, not just for the characterisation of the structure of disordered materials, but also simply for its description. The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local, atomic-scale environment, without the requirement for long-range order, makes it a powerful tool for the study of disorder in the solid state. Information on the number and type(s) of coordinating atoms or through-space and through-bond connectivity between atomic species enables the construction of a detailed picture of the structure. After a brief description of the background theory of NMR spectroscopy, and the experimental methods employed, we will describe the effects of disorder on NMR spectra and the use of calculations to help interpret experimental measurements. We will then review a range of applications to different types of disordered materials, including oxides and ceramics, minerals, porous materials, biomaterials, energy materials, pharmaceuticals, polymers and glasses. We will discuss the most successful approaches for studying different materials, and illustrate the type of information available and the structural insight gained.

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“…Solid-state NMR spectroscopy is ideally suited not only to the study of the local structure of such materials, but also the investigation of the dynamic and electrochemical processes that occur. 14,[107][108][109] Research to date has focussed primarily on lithium battery materials and oxide ion conductors, with 6/7 Li and 17 O NMR attracting considerable recent attention. 14,[107][108][109] However, the experimental challenges posed here do not necessarily result from the quadrupolar nature of these nuclides, but from the need to understand the processes and structural changes that occur under operating conditions, i.e., in situ, to be of real relevance.…”

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confidence: 99%

“…Similar structural investigations of a number of possible candidate materials have been undertaken using 6/7 Li NMR, utilising the ability of the technique to probe local structure and its sensitivity to paramagnetic interactions. 14,[107][108][109] Of increasing interest, however, is the use of in situ NMR to investigate the production of transient states and the dynamic and chemical processes taking place in real time, during the operation of electrochemical devices. 107 In general, in situ experiments are performed (without the use of MAS) on entire devices connected to a potentiostat and NMR spectra are recorded as a function of the charge or discharge state, in approaches pioneered by Tarascon 111 and, more recently, by Grey.…”

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confidence: 99%

“…[107][108][109] In addition to battery and capacitor materials, the increasing application of oxide ion conductors in solid oxide fuel cells, sensors and separators has resulted in considerable NMR investigation of these materials. 109 Despite the need to isotopically enrich in many cases, 17 O NMR spectroscopy has emerged as the method of choice to investigate the local structure and the dynamic processes that take place. An elegant example of this type of study is the work of Kim and Stebbins, where 17 O NMR was used to study motion in Ydoped CeO2, a promising solid-oxide electrolyte material.…”

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New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

2014

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Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future.

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Quadrupolar NMR of Ionic Conductors, Batteries, and Other Energy-related Materials

Cited by 5 publications

References 47 publications

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy

Exploiting NMR spectroscopy for the study of disorder in solids

New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

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Quadrupolar NMR of Ionic Conductors, Batteries, and Other Energy-related Materials

Cited by 5 publications

References 47 publications

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La2NiO4+δ by Solid-State 17O MAS NMR Spectroscopy

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La2NiO4+δ by Solid-State 17O MAS NMR Spectroscopy

Exploiting NMR spectroscopy for the study of disorder in solids

New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

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Product

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Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy

Probing Oxide-Ion Mobility in the Mixed Ionic–Electronic Conductor La₂NiO_4+δ by Solid-State ¹⁷O MAS NMR Spectroscopy