Morphological behavior of thin polyhedral oligomeric silsesquioxane films at the molecular scale

Evmenenko, Guennadi; Stripe, Benjamin; Dutta, Pulak

doi:10.1016/j.jcis.2011.04.073

Cited by 9 publications

(10 citation statements)

References 55 publications

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“…To emphasize changes the reflectivity data, R ( q ), is normalized to the reflectivity from a single interface by being multiplied by q 4 , where q = (4π/λ)sin θ is X-ray momentum transfer along the surface normal. The corresponding Patterson functions, P ( z ), shown in Figure are obtained by taking the Fourier transform of the Fresnel-normalized reflectivity data R ( q )/ R F ( q ). − These directly indicate the presence of electron density fluctuations in the films without any model assumptions or fitting procedures. The positions of the peaks in P ( z ) correspond to the distances between interfaces where the electron density changes.…”

Section: Resultsmentioning

confidence: 99%

Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation

Evmenenko

Fister

Buchholz

et al. 2016

ACS Appl. Mater. Interfaces

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Oxide conversion reactions in lithium ion batteries are challenged by substantial irreversibility associated with significant volume change during the phase separation of an oxide into lithia and metal species (e.g., NiO + 2Li(+) + 2e(-) → Ni + Li2O). We demonstrate that the confinement of nanometer-scale NiO layers within a Ni/NiO multilayer electrode can direct lithium transport and reactivity, leading to coherent expansion of the multilayer. The morphological changes accompanying lithiation were tracked in real-time by in-operando X-ray reflectivity (XRR) and ex-situ cross-sectional transmission electron microscopy on well-defined periodic Ni/NiO multilayers grown by pulsed-laser deposition. Comparison of pristine and lithiated structures reveals that the nm-thick nickel layers help initiate the conversion process at the interface and then provide an architecture that confines the lithiation to the individual oxide layers. XRR data reveal that the lithiation process starts at the top and progressed through the electrode stack, layer by layer resulting in a purely vertical expansion. Longer term cycling showed significant reversible capacity (∼800 mA h g(-1) after ∼100 cycles), which we attribute to a combination of the intrinsic bulk lithiation capacity of the NiO and additional interfacial lithiation capacity. These observations provide new insight into the role of metal/metal oxide interfaces in controlling lithium ion conversion reactions by defining the relationships between morphological changes and film architecture during reaction.

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Section: Resultsmentioning

confidence: 99%

Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation

Evmenenko

Fister

Buchholz

et al. 2016

ACS Appl. Mater. Interfaces

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“…16−20 In a previous study, we observed a variety of structural morphologies in thin films of POSS molecules with side organic chains of different flexibility and deposited from different volatile solvents. 21 The architecture and the composition of side groups defined the morphology of thin films deposited from solution by the dip-coating technique. We showed that the properties of such films can be controlled by tuning the balance between solute−solute and solute−substrate interactions.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Solvent Polarizability on the Assembly and Ordering of Nanoscale Polyhedral Oligomeric Silsesquioxane Films

2013

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Understanding the factors that affect molecular self-assembly is crucial to building designed nanoscale structures. We have deposited nanoscale films of polyhedral oligomeric silsesquioxane (POSS) onto polished silicon substrates from a range of organic solvents. We studied these films using synchrotron X-ray reflectivity and found that dip-coating from benzene, toluene, or chloroform results in near-substrate ordering only, but when acetone, hexane, or THF is used, self-assembled layers are formed throughout the entire deposited film. We conclude that solvent polarizability is the factor that determines the alignment of the POSS molecules. We have successfully tested this prediction using additional solvents selected on the basis of their calculated polarizabilities.

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“…Substrate surface condition plays an important role in the growth and stability of any nanolayer on it. [26][27][28] Nature of the substrate surface can be modified by passivating with foreign atomic layer (such as H, Br, Cl, etc.) or by growing self-assembled monolayers (of say silane).…”

Section: Introductionmentioning

confidence: 99%

“…This essentially modifies the surface-free energy or polar-nonpolar nature of the substrate surface and accordingly, wetting-dewetting or hydrophilicity-hydrophobicity of the surface can be tuned. [27][28][29][30][31][32][33] Strong influence has already been observed in the growth and stability (time-evolution in-plane and out-ofplane structures) of the metal (Ag, Au) nanolayers and of the nickel-arachidate (NiA) LB film on differently passivated Si substrates. 27,34 For the fatty-acid salt molecules, like NiA, presence of both hydrophilic metal-bearing headgroup and hydrophobic hydrocarbon tail affects the structure and stability of the deposited films strongly.…”

Section: Introductionmentioning

confidence: 99%

Reorganization of Au nanoparticle Langmuir-Blodgett films on wet chemically passivated Si(001) surfaces

Kundu

Bal

2011

Journal of Applied Physics

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Surface correlation behaviors of metal-organic Langmuir-Blodgett films on differently passivated Si(001) surfacesGrowth of dodecanethiol-encapsulated Au nanoparticles on differently terminated (OH-, H-, or Br-terminated) Si(001) substrates by Langmuir-Blodgett method at a constant monolayer surface pressure and their out-of-plane structural modification with time have been investigated. As the substrates have different gradations in the hydrophilic/hydrophobic nature, three different out-of-plane structures have been formed. On H-terminated Si (hydrophobic surface), a fluctuating monolayer of Au nanoparticles has been formed, whereas on Br-(coexistence of hydrophilic and hydrophobic surfaces) and OH-terminated Si (hydrophilic surfaces), trilayer of Au nanoparicles have been formed, but the top layer coverage is more for the OH-terminated Si. The growth of Au nanoparticles on H-terminated Si is similar to the Frank-van der Marwe mode, whereas on Br-and OH-terminated Si, the growth is similar to the Stranski-Krastanov mode. These three different structures modify with time and finally become a thicker monolayer of high density, and positions of naoparticles within the monolayer become random. AFM images of the films also show that positions of the Au nanoparticles are random. Density of the final layer becomes maximum on OH-terminated Si and minimum on H-terminated Si, whereas it becomes intermediate on Br-terminated Si. Reorganization thus helps to obtain nanostructures of tunable nanoparticle density.

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Morphological behavior of thin polyhedral oligomeric silsesquioxane films at the molecular scale

Cited by 9 publications

References 55 publications

Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation

Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation

Effect of Solvent Polarizability on the Assembly and Ordering of Nanoscale Polyhedral Oligomeric Silsesquioxane Films

Reorganization of Au nanoparticle Langmuir-Blodgett films on wet chemically passivated Si(001) surfaces

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