Author
Thomas F. Kelly
Other affiliations: Massachusetts Institute of Technology, University of Wisconsin-Madison, PerkinElmer ...read more
Bio: Thomas F. Kelly is an academic researcher from CAMECA. The author has contributed to research in topics: Atom probe & Focused ion beam. The author has an hindex of 37, co-authored 227 publications receiving 11924 citations. Previous affiliations of Thomas F. Kelly include Massachusetts Institute of Technology & University of Wisconsin-Madison.
Papers published on a yearly basis
Papers
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TL;DR: The tensile strengths of individual multiwalled carbon nanotubes (MWCNTs) were measured with a "nanostressing stage" located within a scanning electron microscope and a variety of structures were revealed, such as a nanotube ribbon, a wave pattern, and partial radial collapse.
Abstract: The tensile strengths of individual multiwalled carbon nanotubes (MWCNTs) were measured with a “nanostressing stage” located within a scanning electron microscope. The tensile-loading experiment was prepared and observed entirely within the microscope and was recorded on video. The MWCNTs broke in the outermost layer (“sword-in-sheath” failure), and the tensile strength of this layer ranged from 11 to 63 gigapascals for the set of 19 MWCNTs that were loaded. Analysis of the stress-strain curves for individual MWCNTs indicated that the Young's modulus E of the outermost layer varied from 270 to 950 gigapascals. Transmission electron microscopic examination of the broken nanotube fragments revealed a variety of structures, such as a nanotube ribbon, a wave pattern, and partial radial collapse.
5,011 citations
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TL;DR: The current results demonstrate that specific regions of interest can be accessed and preserved throughout the sample-preparation process and that this preparation method leads to high-quality atom probe analysis of such nano-structures.
1,412 citations
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TL;DR: The technique of atom probe tomography is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future, and how to fabricate suitable specimens from new classes of materials.
Abstract: The technique of atom probe tomography (APT) is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution (sub-0.3-nm) three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.
816 citations
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TL;DR: In this article, a combined theoretical and experimental approach has been used to study nanoscale CoFe/Cu/CoFe multilayer films grown by sputter deposition, and a novel deposition technique is proposed which reduces both interfacial mixing and Fe depletion by controlling the incident adatom energies.
644 citations
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TL;DR: Isolatednanoclusters, measuring about 10nm and spaced 10−50nm apart, are enriched in incompatible elements including radiogenic Pb with unusually high 207 Pb/ 206 Pbratios as discussed by the authors.
Abstract: The only physical evidence from the earliest phases of Earth’s evolution comes from zircons, ancient mineral grains that can be dated using the U‐Th‐Pb geochronometer 1 . Oxygen isotope ratios from such zircons have been used to infer when the hydrosphere and conditions habitable to life were established 2,3 . Chemical homogenization of Earth’s crust and the existence of a magma ocean have not been dated directly, but must have occurred earlier 4 . However, the accuracy of the U‐Pbzirconagescanplausiblybebiasedbypoorlyunderstood processes of intracrystalline Pb mobility 5‐7 . Here we use atomprobe tomography 8 to identify and map individual atoms in the oldest concordant grain from Earth, a 4.4-Gyr-old Hadean zircon with a high-temperature overgrowth that formed about 1Gyrafterthemineral’score.Isolatednanoclusters,measuring about 10nm and spaced 10‐50nm apart, are enriched in incompatible elements including radiogenic Pb with unusually high 207 Pb/ 206 Pbratios.Wedemonstratethatthelengthscales of these clusters make U‐Pb age biasing impossible, and that they formed during the later reheating event. Our tomography data thereby confirm that any mixing event of the silicate Earth must have occurred before 4.4Gyr ago, consistent with
356 citations
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TL;DR: Graphene is established as the strongest material ever measured, and atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.
Abstract: We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.
18,008 citations
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TL;DR: The bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.
Abstract: The remarkable mechanical properties of carbon nanotubes arise from the exceptional strength and stiffness of the atomically thin carbon sheets (graphene) from which they are formed. In contrast, bulk graphite, a polycrystalline material, has low fracture strength and tends to suffer failure either by delamination of graphene sheets or at grain boundaries between the crystals. Now Stankovich et al. have produced an inexpensive polymer-matrix composite by separating graphene sheets from graphite and chemically tuning them. The material contains dispersed graphene sheets and offers access to a broad range of useful thermal, electrical and mechanical properties. Individual sheets of graphene can be readily incorporated into a polymer matrix, giving rise to composite materials having potentially useful electronic properties. Graphene sheets—one-atom-thick two-dimensional layers of sp2-bonded carbon—are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in-plane values for graphite (∼3,000 W m-1 K-1 and 1,060 GPa, respectively); their fracture strength should be comparable to that of carbon nanotubes for similar types of defects1,2,3; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties4,5,6,7,8. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene-polymer composites via complete exfoliation of graphite9 and molecular-level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene–graphene composite formed by this route exhibits a percolation threshold10 of ∼0.1 volume per cent for room-temperature electrical conductivity, the lowest reported value for any carbon-based composite except for those involving carbon nanotubes11; at only 1 volume per cent, this composite has a conductivity of ∼0.1 S m-1, sufficient for many electrical applications12. Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.
11,866 citations
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TL;DR: In this article, a comprehensive review is presented on the researches and developments related to electrospun polymer nanofibers including processing, structure and property characterization, applications, and modeling and simulations.
6,987 citations
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TL;DR: This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them, and summarizes cellulOSE nanoparticles in terms of particle morphology, crystal structure, and properties.
Abstract: This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).
4,920 citations