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Keller AW, Marino E, An D, Neuhaus SJ, Elbert KC, Murray CB, Kagan CR. Sub-5 nm Anisotropic Pattern Transfer via Colloidal Lithography of a Self-Assembled GdF 3 Nanocrystal Monolayer. NANO LETTERS 2022; 22:1992-2000. [PMID: 35226509 DOI: 10.1021/acs.nanolett.1c04761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Patterning materials with nanoscale features opens many research opportunities ranging from fundamental science to technological applications. However, current nanofabrication methods are ill-suited for sub-5 nm patterning and pattern transfer. We demonstrate the use of colloidal lithography to transfer an anisotropic pattern of discrete features into substrates with a critical dimension below 5 nm. The assembly of monodisperse, anisotropic nanocrystals (NCs) with a rhombic-plate morphology spaced by dendrimer ligands results in a well-ordered monolayer that serves as a 2D anisotropic hard mask pattern. This pattern is transferred into the underlying substrate using dry etching followed by removal of the NC mask. We exemplify this approach by fabricating an array of pillars with a rhombic cross-section and edge-to-edge spacing of 4.4 ± 1.1 nm. The fabrication approach enables broader access to patterning materials at the deep nanoscale by implementing innovative processes into well-established fabrication methods while minimizing process complexity.
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2
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Devaraj V, Choi JW, Lee JM, Oh JW. An Accessible Integrated Nanoparticle in a Metallic Hole Structure for Efficient Plasmonic Applications. MATERIALS 2022; 15:ma15030792. [PMID: 35160740 PMCID: PMC8837044 DOI: 10.3390/ma15030792] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 01/02/2023]
Abstract
Addressing the severe deterioration of gap mode properties in spherical-shaped nanoparticles (NPs) becomes necessary due to their utilization in a wide range of multi-disciplinary applications. In this work, we report an integrated plasmonic nanostructure based on a spherical-shaped nanoparticle (NP) in a metallic hole as an alternative to a NP-only structure. With the help of three-dimensional (3D) electromagnetic simulations, we reveal that when a NP is positioned on the top of a metallic hole, it can exhibit superior gap-mode-based local-field intensity enhancement. The integrated nanostructure displayed a ~22-times increase in near-field enhancement characteristics, similar to cube- or disk-shaped nanostructure’s plasmonic properties. From an experimental perspective, the NP positioning on top of the metallic hole can be realized more easily, facilitating a simple fabrication meriting our design approach. In addition to the above advantages, a good geometrical tolerance (metallic hole-gap size error of ~20 nm) supported by gap mode characteristics enhances flexibility in fabrication. These combined advantages from an integrated plasmonic nanostructure can resolve spherical-shaped NP disadvantages as an individual nanostructure and enhance its utilization in multi-disciplinary applications.
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Affiliation(s)
- Vasanthan Devaraj
- Bio-IT Fusion Technology Research Institute, Pusan National University, Busan 46241, Korea;
| | - Jong-Wan Choi
- Department of Chemistry and Life Science, Sahmyook University, Seoul 01795, Korea;
| | - Jong-Min Lee
- School of Nanoconvergence Technology, Hallym University, Chuncheon 24252, Korea
- Center of Nano Convergence Technology, Hallym University, Chuncheon 24252, Korea
- Correspondence: (J.-M.L.); (J.-W.O.)
| | - Jin-Woo Oh
- Bio-IT Fusion Technology Research Institute, Pusan National University, Busan 46241, Korea;
- Department of Nano Fusion Technology and BK21 Plus Nano Convergence Division, Pusan National University, Busan 46241, Korea
- Department of Nanoenergy Engineering, Pusan National University, Busan 46241, Korea
- Correspondence: (J.-M.L.); (J.-W.O.)
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3
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Jackson GL, Lin XM, Austin J, Wen J, Jaeger HM. Ultrathin Porous Hydrocarbon Membranes Templated by Nanoparticle Assemblies. NANO LETTERS 2021; 21:166-174. [PMID: 33301329 DOI: 10.1021/acs.nanolett.0c03450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Porous polymer membranes are widely desired as catalyst supports, sensors, and active layers for separation membranes. We demonstrate that electron beam irradiation of freely suspended gold or Fe3O4 nanoparticle (NP) monolayer sheets followed by wet chemical etching is a high-fidelity strategy to template two-dimensional (2D) porous cross-linked hydrocarbon membranes. This approach, which relies on secondary electrons generated by the NP cores, can further be used to transform three-dimensional (3D) terraced gold NP supercrystals into 3D porous hydrocarbon membranes. We utilize electron tomography to show how the number of NP layers (monolayer to pentalayer) controls attenuation and scattering of the primary e-beam, which in turn determines ligand cross-link density and 3D pore structure. Electron tomography also reveals that many nanopores are vertically continuous because of preferential sintering of NPs. This work demonstrates new routes for the construction of functional nanoporous media.
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Affiliation(s)
- Grayson L Jackson
- James Franck Institute, University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United States
| | - Xiao-Min Lin
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 United States
| | - Jotham Austin
- Advanced Electron Microscopy Facility, University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 United States
| | - Jianguo Wen
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 United States
| | - Heinrich M Jaeger
- James Franck Institute, University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, United States
- Department of Physics, University of Chicago, 5720 S. Ellis Avenue, Chicago, Illinois 60637, United States
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Zhu H, Masson JF, Bazuin CG. Monolayer Arrays of Nanoparticles on Block Copolymer Brush Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5114-5124. [PMID: 30905161 DOI: 10.1021/acs.langmuir.8b04085] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional arrays of nanoparticles (NPs) have widespread applications in optical coatings, plasmonic sensors, and nanocomposites. Current bottom-up approaches that use homogeneous NP templates, such as silane self-assembled monolayers or homopolymers, are typically plagued by NP aggregation, whereas patterned block copolymer (BCP) films require specific compositions for specific NP distributions. Here, we show, using polystyrene- b-poly(4-vinylpyridine) (PS- b-P4VP) and gold NPs (AuNPs) of various sizes, that a nanothin PS- b-P4VP brushlike coating (comprised of a P4VP wetting layer and a PS overlayer), which is adsorbed onto flat substrates during their immersion in very dilute PS- b-P4VP tetrahydrofuran solutions, provides an excellent template for obtaining dense and well-dispersed AuNPs with little aggregation. These non-close-packed arrays have similar characteristics regardless of immersion time in solution (about 10-120 s studied), solution concentration below a critical value (0.1 and 0.05 mg/mL studied), and AuNP diameter (10-90 nm studied). Very dilute BCP solutions are necessary to avoid deposition, during substrate withdrawal, of additional material onto the adsorbed BCP layer, which typically leads to patterned surfaces. The PS brush coverage depends on immersion time (adsorption kinetics), but full coverage does not inhibit AuNP adsorption, which is attributed to PS molecular rearrangement during exposure to the aqueous AuNP colloidal solution. The simplicity, versatility and robustness of the method will enable applications in materials science requiring dense, unaggregated NP arrays.
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Affiliation(s)
- Hu Zhu
- Département de chimie , Université de Montréal , C.P. 6128 Succ. Centre-ville , Montréal , Québec , Canada H3C 3J7
| | - Jean-François Masson
- Département de chimie , Université de Montréal , C.P. 6128 Succ. Centre-ville , Montréal , Québec , Canada H3C 3J7
| | - C Geraldine Bazuin
- Département de chimie , Université de Montréal , C.P. 6128 Succ. Centre-ville , Montréal , Québec , Canada H3C 3J7
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5
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Chen J, Fasoli A, Cushen JD, Wan L, Ruiz R. Self-Assembly and Directed Assembly of Polymer Grafted Nanocrystals via Solvent Annealing. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01921] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Jun Chen
- HGST, a Western Digital Company, San Jose, California 95135, United States
| | - Andrea Fasoli
- HGST, a Western Digital Company, San Jose, California 95135, United States
| | - Julia D. Cushen
- HGST, a Western Digital Company, San Jose, California 95135, United States
| | - Lei Wan
- HGST, a Western Digital Company, San Jose, California 95135, United States
| | - Ricardo Ruiz
- HGST, a Western Digital Company, San Jose, California 95135, United States
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Wen T, Li Y, Zhang D, Zhan Q, Wen Q, Liao Y, Xie Y, Zhang H, Liu C, Jin L, Liu Y, Zhou T, Zhong Z. Manipulate the magnetic anisotropy of nanoparticle assemblies in arrays. J Colloid Interface Sci 2017; 497:14-22. [DOI: 10.1016/j.jcis.2017.02.056] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 01/18/2017] [Accepted: 02/23/2017] [Indexed: 10/20/2022]
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7
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Chang T, Du B, Huang H, He T. Highly Tunable Complementary Micro/Submicro-Nanopatterned Surfaces Combining Block Copolymer Self-Assembly and Colloidal Lithography. ACS APPLIED MATERIALS & INTERFACES 2016; 8:22705-22713. [PMID: 27509255 DOI: 10.1021/acsami.6b07730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two kinds of large-area ordered and highly tunable micro/submicro-nanopatterned surfaces in a complementary manner were successfully fabricated by elaborately combining block copolymer self-assembly and colloidal lithography. Employing a monolayer of polystyrene (PS) colloidal spheres assembled on top as etching mask, polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) or polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) micelle films were patterned into micro/submicro patches by plasma etching, which could be further transferred into micropatterned metal nanoarrays by subsequent metal precursor loading and a second plasma etching. On the other hand, micro/submicro-nanopatterns in a complementary manner were generated via preloading a metal precursor in initial micelle films before the assembly of PS colloidal spheres on top. Both kinds of micro/submicro-nanopatterns showed good fidelity at the micro/submicroscale and nanoscale; meanwhile, they could be flexibly tuned by the sample and processing parameters. Significantly, when the PS colloidal sphere size was reduced to 250 nm, a high-resolution submicro-nanostructured surface with 3-5 metal nanoparticles in each patch or a single-nanoparticle interconnected honeycomb network was achieved. Moreover, by applying gold (Au) nanoparticles as anchoring points, micronanopatterned Au arrays can serve as a flexible template to pattern bovine serum albumin (BSA) molecules. This facile and cost-effective approach may provide a novel platform for fabrication of micropatterned nanoarrays with high tunability and controllability, which are promising in the applications of biological and microelectronic fields.
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Affiliation(s)
- Tongxin Chang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, P. R. China
- University of Chinese Academy of Sciences , Beijing 100039, P. R. China
| | - Binyang Du
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science & Engineering, and Department of Chemistry, Zhejiang University , Hangzhou 310027, P. R. China
| | - Haiying Huang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, P. R. China
- University of Chinese Academy of Sciences , Beijing 100039, P. R. China
| | - Tianbai He
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, P. R. China
- University of Chinese Academy of Sciences , Beijing 100039, P. R. China
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8
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Bao Y, Wen T, Samia ACS, Khandhar A, Krishnan KM. Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine. JOURNAL OF MATERIALS SCIENCE 2016; 51:513-553. [PMID: 26586919 PMCID: PMC4646229 DOI: 10.1007/s10853-015-9324-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 07/31/2015] [Indexed: 05/05/2023]
Abstract
We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body -- an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field.
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Affiliation(s)
- Yuping Bao
- Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, AL 35487
| | - Tianlong Wen
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | | | | | - Kannan M. Krishnan
- Materials Science and Engineering, University of Washington, Seattle, 98195
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9
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Lee J, Pandey P, Sui M, Li MY, Zhang Q, Kunwar S. Evolution of Self-Assembled Au NPs by Controlling Annealing Temperature and Dwelling Time on Sapphire (0001). NANOSCALE RESEARCH LETTERS 2015; 10:494. [PMID: 26704710 PMCID: PMC4690826 DOI: 10.1186/s11671-015-1200-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/14/2015] [Indexed: 05/23/2023]
Abstract
Au nanoparticles (NPs) have been utilized in a wide range of device applications as well as catalysts for the fabrication of nanopores and nanowires, in which the performance of the associated devices and morphology of nanopores and nanowires are strongly dependent on the size, density, and configuration of the Au NPs. In this paper, the evolution of the self-assembled Au nanostructures and NPs on sapphire (0001) is systematically investigated with the variation of annealing temperature (AT) and dwelling time (DT). At the low-temperature range between 300 and 600 °C, three distinct regimes of the Au nanostructure configuration are observed, i.e., the vermiform-like Au piles, irregular Au nano-mounds, and Au islands. Subsequently, being provided with relatively high thermal energy between 700 and 900 °C, the round dome-shaped Au NPs are fabricated based on the Volmer-Weber growth model. With the increased AT, the size of the Au NPs is gradually increased due to a more favorable surface diffusion while the density is gradually decreased as a compensation. On the other hand, with the increased DT, the size and density of Au NPs decrease due to the evaporation of Au at relatively high annealing temperature at 950 °C.
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Affiliation(s)
- Jihoon Lee
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
- Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Puran Pandey
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
| | - Mao Sui
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
| | - Ming-Yu Li
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
| | - Quanzhen Zhang
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
| | - Sundar Kunwar
- College of Electronics and Information, Kwangwoon University, Nowon-gu, Seoul, 139-701, South Korea.
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10
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Jeong HH, Mark AG, Lee TC, Son K, Chen W, Alarcón-Correa M, Kim I, Schütz G, Fischer P. Selectable Nanopattern Arrays for Nanolithographic Imprint and Etch-Mask Applications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2015; 2:1500016. [PMID: 27980957 PMCID: PMC5115431 DOI: 10.1002/advs.201500016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/07/2015] [Indexed: 05/22/2023]
Abstract
A parallel nanolithographic patterning method is presented that can be used to obtain arrays of multifunctional nanoparticles. These patterns can simply be converted into a variety of secondary nanopatterns that are useful for nanolithographic imprint, plasmonic, and etch-mask applications.
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Affiliation(s)
- Hyeon-Ho Jeong
- Max Planck Institute for Intelligent Systems Heisenbergstr. 3 70569 Stuttgart Germany
| | - Andrew G Mark
- Max Planck Institute for Intelligent Systems Heisenbergstr. 3 70569 Stuttgart Germany
| | - Tung-Chun Lee
- Max Planck Institute for Intelligent Systems Heisenbergstr. 370569 Stuttgart Germany; Institute for Materials Discovery University College London Kathleen Lonsdale Building Gower Place London WC1E 6BT UK
| | - Kwanghyo Son
- Max Planck Institute for Intelligent Systems Heisenbergstr. 3 70569 Stuttgart Germany
| | - Wenwen Chen
- Max Planck Institute for Intelligent Systems Heisenbergstr. 370569 Stuttgart Germany; Department of Biophysical Chemistry University of Heidelberg INF 25369120 Heidelberg Germany
| | - Mariana Alarcón-Correa
- Max Planck Institute for Intelligent Systems Heisenbergstr. 370569 Stuttgart Germany; Institute for Physical Chemistry University of Stuttgart Pfaffenwaldring 5570569 Stuttgart Germany
| | - Insook Kim
- Max Planck Institute for Intelligent Systems Heisenbergstr. 370569 Stuttgart Germany; Institute for Physical Chemistry University of Stuttgart Pfaffenwaldring 5570569 Stuttgart Germany
| | - Gisela Schütz
- Max Planck Institute for Intelligent Systems Heisenbergstr. 3 70569 Stuttgart Germany
| | - Peer Fischer
- Max Planck Institute for Intelligent Systems Heisenbergstr. 370569 Stuttgart Germany; Institute for Physical Chemistry University of Stuttgart Pfaffenwaldring 5570569 Stuttgart Germany
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11
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Wen T, Zhang D, Wen Q, Zhang H, Liao Y, Li Q, Yang Q, Bai F, Zhong Z. Magnetic nanoparticle assembly arrays prepared by hierarchical self-assembly on a patterned surface. NANOSCALE 2015; 7:4906-4911. [PMID: 25712606 DOI: 10.1039/c4nr07489k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Inverted pyramid hole arrays were fabricated by photolithography and used as templates to direct the growth of colloidal nanoparticle assemblies. Cobalt ferrite nanoparticles deposit in the holes to yield high quality pyramid magnetic nanoparticle assembly arrays by carefully controlling the evaporation of the carrier fluid. Magnetic measurements indicate that the pyramid magnetic nanoparticle assembly arrays preferentially magnetize perpendicular to the substrate.
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Affiliation(s)
- Tianlong Wen
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China.
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12
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Kim D, Resasco J, Yu Y, Asiri AM, Yang P. Synergistic geometric and electronic effects for electrochemical reduction of carbon dioxide using gold–copper bimetallic nanoparticles. Nat Commun 2014; 5:4948. [DOI: 10.1038/ncomms5948] [Citation(s) in RCA: 908] [Impact Index Per Article: 90.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/10/2014] [Indexed: 12/24/2022] Open
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13
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Grojo D, Sandeau N, Boarino L, Constantinescu C, De Leo N, Laus M, Sparnacci K. Bessel-like photonic nanojets from core-shell sub-wavelength spheres. OPTICS LETTERS 2014; 39:3989-92. [PMID: 24978789 DOI: 10.1364/ol.39.003989] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
It is accepted so far that the formation of photonic nanojets requires the use of large dielectric spheres (several wavelengths in diameter). Here we show both numerically and experimentally that similar effects can be obtained with properly engineered sub-wavelength core-shell colloids. The design of the spheres is strongly inspired by a far-field approach for the generation of Bessel beams.
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14
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Sundar V, Zhu J, Laughlin DE, Zhu JGJ. Novel scheme for producing nanoscale uniform grains based on templated two-phase growth. NANO LETTERS 2014; 14:1609-1613. [PMID: 24548292 DOI: 10.1021/nl500061t] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Future magnetic recording media require firm control of the microstructure particularly with uniform grain size at the nanometer scale. Using self-assembling block copolymers as an etch-mask, a novel underlayer is patterned with a carefully designed surface morphology. Two-phase growth with magnetic grains encircled by an oxide phase is guided by the templated underlayer to create high-coercivity magnetic media with uniform grain size at the nanoscale.
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Affiliation(s)
- Vignesh Sundar
- Data Storage Systems Center, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
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15
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Zhang M, Bechstein DJB, Wilson RJ, Wang SX. Wafer-scale synthesis of monodisperse synthetic magnetic multilayer nanorods. NANO LETTERS 2014; 14:333-8. [PMID: 24329003 PMCID: PMC3931460 DOI: 10.1021/nl404089t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A double exposure technique has been used to fabricate nanoimprint stamps for making monodisperse nanorods with controllable lengths. The nanorod length is defined by a normal photolithography projection process whereas the nanorod width is defined by an edge-lithography process using a soft polydimethylsiloxane (PDMS) contact mask. Taking advantage of edge-lithography, the nanorod width can be less than the diffraction limit of the exposure light. Using these nanorod stamps, synthetic magnetic multilayer (SMM) nanorods have been fabricated using nanoimprint lithography, resulting in a length variation of ∼3%. Nanorod magnetic properties have been characterized in both longitudinal and in-plane transverse directions of the nanorods. A theoretical model has been established to explain the magnetic responses and has revealed that both shape anisotropy and interlayer interactions are important in determining the properties of SMM nanorods.
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Affiliation(s)
- Mingliang Zhang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305
| | | | - Robert J. Wilson
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305
| | - Shan X. Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305
- Department of Electrical Engineering, Stanford University, Stanford, California, 94305
- Corresponding Author:
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16
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Wen T, Brush LN, Krishnan KM. A generalized diffusion model for growth of nanoparticles synthesized by colloidal methods. J Colloid Interface Sci 2013; 419:79-85. [PMID: 24491334 DOI: 10.1016/j.jcis.2013.12.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/06/2013] [Accepted: 12/07/2013] [Indexed: 11/30/2022]
Abstract
A nanoparticle growth model is developed to predict and guide the syntheses of monodisperse colloidal nanoparticles in the liquid phase. The model, without any a priori assumptions, is based on the Fick's law of diffusion, conservation of mass and the Gibbs-Thomson equation for crystal growth. In the limiting case, this model reduces to the same expression as the currently accepted model that requires the assumption of a diffusion layer around each nanoparticle. The present growth model bridges the two limiting cases of the previous model i.e. complete diffusion controlled and adsorption controlled growth of nanoparticles. Specifically, the results show that a monodispersion of nanoparticles can be obtained both with fast monomer diffusion and with surface reaction under conditions of small diffusivity to surface reaction constant ratio that results is growth 'focusing'. This comprehensive description of nanoparticle growth provides new insights and establishes the required conditions for fabricating monodisperse nanoparticles critical for a wide range of applications.
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Affiliation(s)
- Tianlong Wen
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195-2120, USA
| | - Lucien N Brush
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195-2120, USA
| | - Kannan M Krishnan
- Department of Materials Science and Engineering, University of Washington, Box 352120, Seattle, WA 98195-2120, USA.
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