Nucleation, evolution, and growth dynamics of amorphous silica nanosprings

Wojcik, Peter M.; Bakharev, Pavel V.; Corti, Giancarlo; McIlroy, David N.

doi:10.1088/2053-1591/aa54dc

Cited by 14 publications

(16 citation statements)

References 48 publications

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“…Because the energy required to bifurcate a catalyst nanoparticle is larger than the energy required to merge them, no smaller individual SN are grown with increasing. 23 This suggests that as the SN mat grows thicker, silica nanospring coalesce into larger and thicker SN (Figure 5) as shown by the SN measurements of Table 2. The growth mechanism of silica nanosprings and the SN mat dimensions at different thicknesses shown in Table 2 suggest a unique structure with a pore size and a silica nanospring that gradually increase in dimension with the thickness of the SN mat.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 81%

“…As the SN reaction begins, the SN catalyst diffuses and nucleates on the sample surface, creating islands, which later catalyze the precursor to form onedimensional nanowires. 23 During this island formation step, large areas of the substrate are depleted of the catalyst, exposing the underlying base material, in this case, aluminum. In addition, these silica nanowires merge as their catalyst nanoparticles coalesce into a single catalyst with a bundle of nanowires that cohesively coil together forming the silica nanosprings.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

“…23,24 The SN geometry (Figure 1) provides a unique combination of nano-and microdimensions within the SN itself and the SN mat. Wojcik et al identified that the twisting and bundling of the nanowires that form SN minimize the free energy, and thus bifurcation is energetically disfavorable, 23 suggesting that longer growth times will produce thicker and longer silica nanosprings, effectively altering the SN mat topology. Silica nanosprings are a nonporous high surface area nanomaterial with a high ratio of air to solid.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Methyl-Functionalized Silica Nanosprings for Superhydrophobic and Defrosting Coatings

Corti

Schmiesing

Barrington

et al. 2019

ACS Appl. Mater. Interfaces

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Thin non-perfluoroalkoxy superhydrophobic coatings are desirable for heat exchangers because of their lower thermal resistance and reduced environmental concerns. Coatings requirements must also include robustness and longevity and facilitate high defrosting rates in refrigeration applications to warrant their adoption and use. Methylfunctionalized silica nanosprings (SN) possess water droplet static contact angles above 160°with contact angle hysteresis values as low as 6.9°for a sub-micrometer-thick coating. The methyl functional groups render the silica surface hydrophobic, whereas the geometrical and topographical characteristics of the nanosprings make it super-hydrophobic. Results show that SN are capable of removing 95% of the frost from the surface at a lower temperature than the base aluminum substrate. The sub-micrometer SN coating also decreases the time to defrost by ≈1.5 times and can withstand more than 20 frosting− defrosting cycles in a high humidity environment akin to real working conditions for heat exchangers.

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Section: Acs Applied Materials and Interfacesmentioning

confidence: 81%

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of Methyl-Functionalized Silica Nanosprings for Superhydrophobic and Defrosting Coatings

Corti

Schmiesing

Barrington

et al. 2019

ACS Appl. Mater. Interfaces

Self Cite

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“…Nanosprings grow via a modified vapor-liquid-solid growth mechanism, as reported by McIlroy et al [45][46][47][48][49], where we refer readers to the references for the details. p-type Si(100) substrates were used for all the samples in this study, with or without silica NS mats.…”

Section: Growth Details and Characterizationmentioning

confidence: 91%

High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures

et al. 2020

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Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al2O3 or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures.

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“…Silica NSs were grown in bulk on silicon substrates using a method previously described by Wojcik et al [29] and Wang et al [30]. GUITAR was deposited onto the silica NS surface via the pyrolysis of commercial roofing tar (asphalt) in a tube furnace operating at 800 °C under a continuous flow of nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Utilizing a Single Silica Nanospring as an Insulating Support to Characterize the Electrical Transport and Morphology of Nanocrystalline Graphite

et al. 2019

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A graphitic carbon, referred to as graphite from the University of Idaho thermolyzed asphalt reaction (GUITAR), was coated in silica nanosprings and silicon substrates via the pyrolysis of commercial roofing tar at 800 °C in an inert atmosphere. Scanning electron microscopy and transmission electron microscopy images indicate that GUITAR is an agglomeration of carbon nanospheres formed by the accretion of graphitic flakes into a ~100 nm layer. Raman spectroscopic analyses, in conjunction with scanning electron microscopy and transmission electron microscopy, indicate that GUITAR has a nanocrystalline structure consisting of ~1–5 nm graphitic flakes interconnected by amorphous sp3 bonded carbon. The electrical resistivities of 11 single GUITAR-coated nanospring devices were measured over a temperature range of 10–80 °C. The average resistivity of all 11 devices at 20 °C was 4.3 ± 1.3 × 10−3 Ω m. The GUITAR coated nanospring devices exhibited an average negative temperature coefficient of resistivity at 20 °C of −0.0017 ± 0.00044 °C−1, which is consistent with the properties of nanocrystalline graphite.

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Nucleation, evolution, and growth dynamics of amorphous silica nanosprings

Cited by 14 publications

References 48 publications

Characterization of Methyl-Functionalized Silica Nanosprings for Superhydrophobic and Defrosting Coatings

Characterization of Methyl-Functionalized Silica Nanosprings for Superhydrophobic and Defrosting Coatings

High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures

Utilizing a Single Silica Nanospring as an Insulating Support to Characterize the Electrical Transport and Morphology of Nanocrystalline Graphite

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