Advanced Dipolar Solid State Nmr Spectroscopy of Glasses

Eckert, Hellmut

doi:10.1002/9781119051862.ch9

Cited by 8 publications

(19 citation statements)

References 120 publications

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“…Dotted curve: statistical distribution of connectivities expected at a B/Si ratio of unity 63 ECKERT | 179 containing the intermediate oxide Al 2 O 3 as summarized in various contributions 64,65 and reviews. [66][67][68] Alongside, they have been used to explore distance relations between network former and network modifier species offering insights into spatial distributions of the network modifiers and the mechanisms of local charge compensation. 52,[66][67][68][69] In particular, these methods have provided unique insights into the structural origins of network former mixing effects upon thermal and mechanical stabilities and ionic conductivities in many ion-conducting systems.…”

Section: Connectivity Distribution In Mixednetwork Glasses Studied mentioning

confidence: 99%

Spying with spins on messy materials: 60 Years of glass structure elucidation byNMRspectroscopy

Eckert

2018

Int J of Appl Glass Sci

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Glasses remain a focus of attraction to fundamental researchers and materials engineers alike. The desire of controlling physical property combinations by compositional design inspires the search for fundamental structural concepts describing the short‐ and medium‐range order of the glassy state. From its early beginnings more than 60 years ago, solid‐state nuclear magnetic resonance (NMR) spectroscopy has been making significant contributions toward this objective. Being element‐selective, inherently quantitative as well as selective to the local environment, NMR in many ways presents an ideal experimental tool of structural investigation of glasses. Over the years, substantial NMR methods development, along with advances in the theoretical interpretation of NMR parameters, have significantly enhanced our fundamental knowledge of medium‐range order and of composition‐structure‐function relationships. As we are approaching the 60th anniversary of the publication of the first article dealing with this topic (A.H. Silver and P.J. Bray, The Journal of Chemical Physics 1958, 29, 984), it is time to look back at the amazing scientific trajectory this field of investigation has taken, from the early beginnings to the present state of the art. As such, this overview does not strive to be comprehensive, but adopts a personal perspective, highlighting what in the view of the author have been influential developments and important insights obtained during the various phases of scientific inquiry in this research field.

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Section: Connectivity Distribution In Mixednetwork Glasses Studied mentioning

confidence: 99%

Spying with spins on messy materials: 60 Years of glass structure elucidation byNMRspectroscopy

Eckert

2018

Int J of Appl Glass Sci

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“…These advances form the elements of an integrated experimental strategy combining all of these methods, as proposed many years ago 23 and developed further in recent years. 24 In the present contribution, we wish to use this approach based on a comprehensive analysis of internuclear homo-and heteronuclear spin−spin interactions among the constituent nuclei 23 Na, 29 Si, and 31 P in phosphate-rich sodium phosphosilicate glasses. Phosphate-rich compositions of this system feature silicon in six coordinations, 25 otherwise only known to exist in silicate glasses prepared at elevated pressures.…”

Section: ■ Introductionmentioning

confidence: 99%

“… Over the years, substantial NMR method development, , along with advances in the theoretical interpretation of NMR parameters, have significantly enhanced our fundamental knowledge of medium-range order and of composition-structure–function relationships in glasses. These advances form the elements of an integrated experimental strategy combining all of these methods, as proposed many years ago and developed further in recent years …”

Section: Introductionmentioning

confidence: 99%

Superstructural Units Involving Six-Coordinated Silicon in Sodium Phosphosilicate Glasses Detected by Solid-State NMR Spectroscopy

Ren

Eckert

2018

J. Phys. Chem. C

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Sodium phosphosilicate glasses with high phosphate contents represent an unusual case in glass science as they are known to contain large amounts of six-coordinated silicon species (SiO6/2 units, Si(6)). Although the network connectivity of these units has been previously investigated, the overall structural organization of this system at the medium-range order level is still incompletely understood. In the present study, this issue is addressed by using a comprehensive suite of homo- and heteronuclear dipolar recoupling studies involving the nuclear isotopes 23Na, 29Si, and 31P on isotopically enriched glasses in the systems xSiO2–(1 – x)(0.45Na2O–0.55P2O5) (x = 0.0, 0.1, and 0.2) and 0.2SiO2–0.2Na2O–0.6P2O5. Four- and six-fold coordinated silicon species (Si(4) and Si(6)) coexist in these glasses. Invariably, Si(6) selectively connects with phosphate species, which are exclusively of the P(3) type, whereas the Si(4) species are coordinated to both P(2) and P(3) units. 29Si ↔ 23Na and 31P ↔ 23Na rotational echo double resonance experiments indicate much closer sodium/phosphorus than sodium/silicon proximities. Evidently, the bond valence gradient of the Si(6)–O–P(3) linkages redistributes the anionic charge onto the phosphate nonbridging oxygen species, which attract Na+ cations. The Si(6)(P(3))6Na2 superstructural units (stoichiometry Na2SiP6O18) thus formed represent an exceptionally high degree of medium-range order, accounting for high thermal and mechanical stability of these glasses. The Na+ ions neutralize the negative charge located at nonbridging oxygen atoms of P(3) tetrahedra, whereas the bridging oxygen atoms in the Si(6)–O–P bonds are electrically neutral. Finally, we show that the structural speciations of silicon and phosphorus in SiO2–Na2O–P2O5 glasses can be predicted straightforwardly from the elemental glass compositions in excellent agreement with experimental results.

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“…While conventional magic-angle spinning (MAS) is well suited for quantifying short-range order environments, information on the medium-range order can be obtained by combining MAS with specifically designed dipolar recoupling techniques . Using advanced techniques, such as rotational echo double resonance (REDOR) and related methods, new quantitative information is available about network former bonds and the spatial distributions of individual glass components …”

Section: Introductionmentioning

confidence: 99%

“…10 Using advanced techniques, such as rotational echo double resonance (REDOR) and related methods, new quantitative information is available about network former bonds and the spatial distributions of individual glass components. 11 ■ EXPERIMENTAL SECTION Sample Preparation and Characterization. The precise batch compositions are given in Table 1.…”

Section: ■ Introductionmentioning

confidence: 99%

Short- and Medium-Range Order in Photothermal Refractive Glass Revealed by Solid-State NMR Techniques

et al. 2019

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Photo-thermo-refractive (PTR) glass is an optically transparent photosensitive Na 2 O−ZnO−Al 2 O 3 − SiO 2 glass, containing NaF and KBr additives, along with cerium, silver, tin, and antimony oxide dopants. After heating above 500 °C, UV-exposed regions of this glass produce permanent refractive index changes, resulting from precipitation of NaF nanocrystals. Short-and medium-range order of this glass system is studied via multinuclear single-and double-resonance solid-state nuclear magnetic resonance (NMR) spectroscopy in regular PTR glass and in model glasses with simplified compositions. The results, when combined with data from energy-dispersive X-ray spectroscopy, indicate that the NaF component modifies the standard aluminosilicate framework, producing small amounts of F-bonded fiveand six-coordinated aluminum species. The fluoride speciation is obtained from 19 F magic-angle spinning NMR spectra, supported by 19 F{ 27 Al} and 19 F{ 23 Na} dipolar recoupling experiments. The majority of fluoride within the PTR glass is found within Na-dominated local environments, which also interact strongly with the aluminum. 23 Na{ 19 F} rotational echo double resonance reveals that about 1/3 of the Na + ions have fluoride ions in their first coordination spheres.

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Advanced Dipolar Solid State Nmr Spectroscopy of Glasses

Cited by 8 publications

References 120 publications

Spying with spins on messy materials: 60 Years of glass structure elucidation byNMRspectroscopy

Spying with spins on messy materials: 60 Years of glass structure elucidation byNMRspectroscopy

Superstructural Units Involving Six-Coordinated Silicon in Sodium Phosphosilicate Glasses Detected by Solid-State NMR Spectroscopy

Short- and Medium-Range Order in Photothermal Refractive Glass Revealed by Solid-State NMR Techniques

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