Size Effects on the Nuclear Magnetic Resonance of Sodium Metal Confined in Controlled Pore Glasses

Terskikh, V. V.; Moudrakovski, Igor L.; Ratcliffe, Christopher I.; Ripmeester, John A.; Reinhold, Catherine; Anderson, Paul A.; Edwards, Peter P.

doi:10.1007/978-94-010-0534-0_41

Cited by 3 publications

(3 citation statements)

References 23 publications

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“…It is known that the NMR spectra of small metal particles are broadened because of surface effects , and such an effect was considered to operate in NMR studies of sodium in controlled pore-size silica . The changes with temperature observed here were not caused primarily by particle size.…”

Section: Resultsmentioning

confidence: 75%

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Dye

Nandi²,

Jackson³

et al. 2011

Chem. Mater.

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Liquid alkali metals and their alloys can be absorbed into the 15 nm diameter pores of nanostructured silica gel (SG) at loadings up to 40 wt %. Characterization of the resultant materials was done by measuring the amount of hydrogen produced by addition of alcohols and/ or water, by differential scanning calorimetry, and by static 23 Na NMR spectroscopy. While sodium must be heated above 100 °C to form Na in SG, absorption of NaÀK alloys at ambient temperatures yields nanoscale metallic clusters in the pores (Stage 0). In both cases, some of the encapsulated metal may dissolve in the silica and ionize to produce highly mobile M þ ions with reversible electron transfer to the silica. This presumption is consistent with literature observations that sodium is soluble in silica films at ambient temperatures at levels up to 35 mol percent and is presumed to form highly mobile Na þ -O À species (Lagarde, P.; Flank, A.-M.; Mazzara, C.; Jupille, J. Surf. Sci. 2001, 482À485, 376À380). Heating M-SG materials leads to reduction of SiO 2 to form material that contains localized M þ -O À species and SiÀSi bonds in increased proportion as the temperature and time of heating are increased. Above 350 °C, elemental silicon, alkali metal silicides, and alkali metal silicates are formed. The dissolution and reaction of potassium from encapsulated NaÀK alloys occurs preferentially over that of sodium. Irreversible reaction even occurs at room temperature over a period of months. The temperature dependence of solid state 23 Na NMR spectra indicates the presence of rapid exchange between Na 0 in the metal clusters and Na þ at the walls (and perhaps within the silica).

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Section: Resultsmentioning

confidence: 75%

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Dye

Nandi²,

Jackson³

et al. 2011

Chem. Mater.

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“…On the micron scale (Ge metal), the isotropic peak for Ge is 10 Hz or 0.3 ppm broad. This effect in NMR has been reported in the past for many materials including 23 Na or 207 Pb NMR of Na or Pb metal confined in porous glass, 195 Pt NMR of small particles, or 63 Cu NMR of silica-supported colloidal copper particles, among others. − Further analysis of this broader 73 Ge component to lower frequency (400 °C, attributed to a noncubic Ge chemical environment) is limited because of the long 73 Ge NMR experimental times (∼48 h).…”

Section: Resultsmentioning

confidence: 81%

Thermally Induced Evolution of “Ge(OH)₂”: Controlling the Formation of Oxide-Embedded Ge Nanocrystals

2018

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Germanium nanocrystals (GeNCs) hold great promise as active materials in many applications including solar cells, biological imaging, Bragg reflectors, light-emitting diodes, and nonvolatile memory devices. However, because of the size-, shape-, and composition-dependent nature of their properties, it is essential that methods affording high-purity, well-defined GeNCs be developed. Herein, we report a systematic investigation of a series of “Ge(OH)2” precursors using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and solid-state 73Ge NMR and correlate their properties with the GeNCs obtained from their thermal processing. This study provides important insights into the role of the Ge(OH)2 internal structure and will allow for future rational design and practical application of GeNCs.

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“…Magnetic shielding can also be influenced by the local electronic structure, which is discussed further below. These effects are not unique to SiNPs and have been reported for numerous nanomaterials, including InP, Zn 3 P 2 , ZnSe, Cd, Na, Ag, Pb, etc. ,− …”

Section: Results and Discussionmentioning

confidence: 83%

Silicon Nanoparticles: Are They Crystalline from the Core to the Surface?

Thiessen

Hooper

et al. 2019

Chem. Mater.

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Silicon nanoparticles (SiNPs) are biologically compatible, metal-free quantum dots that exhibit size and surface tailorable photoluminescence. The nanostructure of these materials influences their optical, chemical, and material properties and hence plays an important role in their futuregeneration applications in sensors, battery electrodes, optical materials, and contrast agents, among others. In this work, we employ a complement of methods including X-ray photoelectron spectroscopy (XPS), bright-field transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and 29 Si solid-state nuclear magnetic resonance (NMR) spectroscopy to interrogate the bulk structure of hydride-terminated SiNPs (H-SiNPs) ranging from 3 to 64 nm in diameter and effectively probe their surface. By applying these methods, we have demonstrated that H-SiNPs consist of a size dependent layered structure made up of surface, subsurface, and core silicon regimes. The surface silicon species are manifested by a broad underlying feature in the corresponding 29 Si NMR spectra between −80 to −120 ppm for small nanoparticles (NPs), whereas the sharp resonance at higher frequency (ca. −80.9 ppm, 1 ppm full-width at half-maximum) present in large NPs is attributed to a well-ordered crystalline silicon core. A critical size junction has been identified for 9 nm H-SiNPs, where XPS and NMR show features arising from surface, subsurface, and core silicon species features arising from surface, subsurface, and core silicon species. This structural insight provides essential understanding and potential advancement in the development of SiNP-based applications in photovoltaics, battery anodes, and sensors.

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Size Effects on the Nuclear Magnetic Resonance of Sodium Metal Confined in Controlled Pore Glasses

Cited by 3 publications

References 23 publications

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Thermally Induced Evolution of “Ge(OH)₂”: Controlling the Formation of Oxide-Embedded Ge Nanocrystals

Silicon Nanoparticles: Are They Crystalline from the Core to the Surface?

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Size Effects on the Nuclear Magnetic Resonance of Sodium Metal Confined in Controlled Pore Glasses

Cited by 3 publications

References 23 publications

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Nano-Structures and Interactions of Alkali Metals within Silica Gel

Thermally Induced Evolution of “Ge(OH)2”: Controlling the Formation of Oxide-Embedded Ge Nanocrystals

Silicon Nanoparticles: Are They Crystalline from the Core to the Surface?

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Product

Resources

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Thermally Induced Evolution of “Ge(OH)₂”: Controlling the Formation of Oxide-Embedded Ge Nanocrystals