Bibliographies thématiques / Core-shell Nanomaterials

Littérature scientifique sur le sujet « Core-shell Nanomaterials »

Auteur : Grafiati
Publié le 7 septembre 2023

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Articles de revues sur le sujet "Core-shell Nanomaterials"

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Arici, Elif, Dieter Meissner, F. Schäffler et N. Serdar Sariciftci. « Core/shell nanomaterials in photovoltaics ». International Journal of Photoenergy 5, no 4 (2003) : 199–208. http://dx.doi.org/10.1155/s1110662x03000333.

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Hybrid materials consist of inorganic nanoparticles embedded in polymer matrices. An advantage of these materials is to combine the unique properties of one or more kinds of inorganic nanoparticles with the film forming properties of polymers. Most of the polymers can be processed from solution at room temperature enabling the manufacturing of large area, flexible and light weight devices. To exploit the full potential for the technological applications of the nanocrystalline materials, it is very important to endow them with good processing attributes. The surface of the inorganic cluster can be modified during the synthesis by organic surfactants. The surfactant can alter the dispersion characteristic of the particles by initiating attractive forces with the polymer chains, in which the particles should be homogenously arranged. In this review, we present wet chemical methods for the synthesis of nanoparticles, which have been used as photovoltaic materials in polymer blends. The photovoltaic performance of various inorganic/organic hybrid solar cells, prepared via spin-coating will be the focus of this contribution.
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Ribeiro, Mota, Júnior, Lima, Fechine, Denardin, Carbone, Bloise, Mele et Mazzetto. « Nanomaterials Based on Fe3O4 and Phthalocyanines Derived from Cashew Nut Shell Liquid ». Molecules 24, no 18 (9 septembre 2019) : 3284. http://dx.doi.org/10.3390/molecules24183284.

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In this work we report the synthesis of new hybrid nanomaterials in the core/shell/shell morphology, consisting of a magnetite core (Fe3O4) and two consecutive layers of oleic acid (OA) and phthalocyanine molecules, the latter derived from cashew nut shell liquid (CNSL). The synthesis of Fe3O4 nanoparticle was performed via co-precipitation procedure, followed by the nanoparticle coating with OA by hydrothermal method. The phthalocyanines anchorage on the Fe3O4/OA core/shell nanomaterial was performed by facile and effective sonication method. The as obtained Fe3O4/OA/phthalocyanine hybrids were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, UV-visible spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis and magnetic measurements. TEM showed round-shaped nanomaterials with sizes in the range of 12–15 nm. Nanomaterials presented saturation magnetization (Ms) in the 1–16 emu/g and superparamagnetic behavior. Furthermore, it was observed that the thermal stability of the samples was directly affected by the insertion of different transition metals in the ring cavity of the phthalocyanine molecule.
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Tsamos, Dimitris, Athina Krestou, Maria Papagiannaki et Stergios Maropoulos. « An Overview of the Production of Magnetic Core-Shell Nanoparticles and Their Biomedical Applications ». Metals 12, no 4 (31 mars 2022) : 605. http://dx.doi.org/10.3390/met12040605.

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Several developments have recently emerged for core-shell magnetic nanomaterials, indicating that they are suitable materials for biomedical applications. Their usage in hyperthermia and drug delivery applications has escalated since the use of shell materials and has several beneficial effects for the treatment in question. The shell can protect the magnetic core from oxidation and provide biocompatibility for many materials. Yet, the synthesis of the core-shell materials is a multifaceted challenge as it involves several steps and parallel processes. Although reviews on magnetic core-shell nanoparticles exist, there is a lack of literature that compares the size and shape of magnetic core-shell nanomaterials synthesized via various methods. Therefore, this review outlines the primary synthetic routes for magnetic core-shell nanoparticles, along with the recent advances in magnetic core-shell nanomaterials. As core-shell nanoparticles have been proposed among others as therapeutic nanocarriers, their potential applications in hyperthermia drug delivery are discussed.
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Sepahvand, R., S. Alihosseini, M. Adeli et P. Sasanpour. « Fullerene-Gold Core-Shell Structures and Their Self-Assemblies ». International Journal of Nanoscience 16, no 02 (24 janvier 2017) : 1650029. http://dx.doi.org/10.1142/s0219581x16500290.

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Hybrid nanomaterials consisting of functionalized fullerene and gold nanoparticle (NP) have been synthesized. Fullerene was functionalized by citric acid and used as reducing and capping agent for preparation of gold NPs. Functionalization of fullerene by use of citric acid was performed by enzymatic and thermal approaches. The core-shell structures containing gold NPs as core and fullerene as shell (gold/fullerene) were prepared. It was found that method and density of functionalization of fullerene effect final structure and therefore their physicochemical property of hybrid nanomaterial dramatically. Ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) were used to analyze the structure of the synthesized hybrid nanomaterial and also study their self-assembly and physicochemical properties. Effect of the size, structure and morphology (e.g., agglomeration) of the synthesized hybrid nanomaterial on their UV-Vis absorption behavior has been also verified by theoretical modeling.
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Zhang, Xiao-kai, Lei Xia, Xue Li et Lian-dong Liu. « Preparation and spectral properties of CuSe/ZnSe core-shell nanomaterials ». Europhysics Letters 136, no 2 (1 octobre 2021) : 26001. http://dx.doi.org/10.1209/0295-5075/136/26001.

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Abstract In this research, first, CuSe nanoparticles (NPs) were synthesized by using the reflux condensation method. Then, a ZnSe shell was grown on the CuSe NPs by using a simple, rapid photochemical approach. Synthesized CuSe/ZnSe core-shell NPs were characterized by means of different analyses, such as X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. The XRD analysis of the sample shows the formation of core-shell NPs with the structure of hexagonal CuSe and cubic ZnSe. The core-shell structure of the product has been formed and the size of the synthesized core-shell NPs is about 20–50 nm. The band gap of the CuSe/ZnSe core-shell NPs was higher than that for CuSe or ZnSe in bulk. The fluorescence properties were greatly enhanced by successful growth of the ZnSe shell and decreased with the extension of illumination time.
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Loghina, Liudmila, Maksym Chylii, Anastasia Kaderavkova, Stanislav Slang, Petr Svec, Jhonatan Rodriguez Pereira, Bozena Frumarova, Miroslav Cieslar et Miroslav Vlcek. « Highly Efficient and Controllable Methodology of the Cd0.25Zn0.75Se/ZnS Core/Shell Quantum Dots Synthesis ». Nanomaterials 11, no 10 (5 octobre 2021) : 2616. http://dx.doi.org/10.3390/nano11102616.

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The surface of any binary or multi-component nanocrystal has imperfections and defects. The number of surface defects depends both on the nature of the nanomaterial and on the method of its preparation. One of the possibilities to confine the number of surface defects is the epitaxial growth of the shell, which leads to a change in the physical properties while maintaining the morphology of the core. To form a shell of the desired thickness, an accurate calculation of the amount of its precursors is substantial to avoid the appearance of individual crystals consisting of the shell material. This study aimed to develop an effective calculation method for the theoretical amount of precursors required for the formation of a ZnS shell on the surface of a Cd0.25Zn0.75Se core, followed by the practical implementation of theoretical calculations and characterization of the prepared nanomaterials. This method allows the complete control of the masses and volumes of the initial reagents, which will in turn prevent undesirable nucleation of nuclei consisting of the shell material. In the synthesis of Cd0.25Zn0.75Se/ZnS core/shell quantum dots (QDs), the sources of chalcogens were substituted seleno- and thioureas, which are capable of not only supplanting modern toxic sources of sulfur and selenium but also allowing one to perform the controlled synthesis of highly photoluminescent QDs with a low number of surface defects. The result of this shell overcoating method was an impetuous augmentation in the photoluminescence quantum yield (PL QY up to 83%), uniformity in size and shape, and a high yield of nanomaterials. The developed synthetic technique of core/shell QDs provides a controlled growth of the shell on the core surface, which makes it possible to transfer this method to an industrial scale.
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Rakgalakane, B. P., et M. J. Moloto. « Aqueous Synthesis and Characterization of CdSe/ZnO Core-Shell Nanoparticles ». Journal of Nanomaterials 2011 (2011) : 1–6. http://dx.doi.org/10.1155/2011/514205.

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Core-shell nanomaterials based on CdSe as the core and ZnO as the shell were prepared using an aqueous route involving the use of Cd salt and NaBH4in reaction with Se to generate CdSe in the presence of thioglycerol (TG) as a stabilizer. ZnO has been prepared at pH 12 using stronger base such as NaOH at lower concentration and by varying amounts of Zn2+ions ranging from 2.5, 5, 25 mL, and 50 mL to prepare core-shell nanomaterials. The absorption and emission spectral features are dominated by CdSe nanoparticles with typical shift in the emission maxima red-shifted in relation to the band edges. There is an observable change in the band edge from the core as the amount of ZnO is increased. The TEM features showed the formation of the core-shell from the volume of 5 mL which is indicated by the thin layer of shell on the surface of the CdSe core.
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Mallick, Sadhucharan, Kshitij RB Singh, Vanya Nayak, Jay Singh et Ravindra Pratap Singh. « Potentialities of core@shell nanomaterials for biosensor technologies ». Materials Letters 306 (janvier 2022) : 130912. http://dx.doi.org/10.1016/j.matlet.2021.130912.

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Kalambate, Pramod K., Dhanjai, Zhimei Huang, Yankai Li, Yue Shen, Meilan Xie, Yunhui Huang et Ashwini K. Srivastava. « Core@shell nanomaterials based sensing devices : A review ». TrAC Trends in Analytical Chemistry 115 (juin 2019) : 147–61. http://dx.doi.org/10.1016/j.trac.2019.04.002.

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Wang, Lingyan, Hye-Young Park, Stephanie I.-Im Lim, Mark J. Schadt, Derrick Mott, Jin Luo, Xin Wang et Chuan-Jian Zhong. « Core@shell nanomaterials : gold-coated magnetic oxide nanoparticles ». Journal of Materials Chemistry 18, no 23 (2008) : 2629. http://dx.doi.org/10.1039/b719096d.

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Thèses sur le sujet "Core-shell Nanomaterials"

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Cho, Sung-Jin. « Synthesis and characterization of core/shell structured magnetic nanomaterials / ». For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.

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Ramoroka, Morongwa Emmanuel. « Photophysics of Thiophenosalicylaldimine-functionalized G1-Polyprolyleniminato-Copper Telluride/Antimonide core-shell Nanomaterials ». University of the Western Cape, 2018. http://hdl.handle.net/11394/6262.

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Magister Scientiae - MSc (Chemistry)
This work involves the synthesis of copper telluride-polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (CuTe@PPI) and copper antimonide-polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (CuSb@PPI) core-shell nanoparticles (NPs), using two-pots and one-pot synthesis methods, respectively. Their morphology was studied by X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM) and high resolution scanning electron microscopy (HRSEM); while their structures were characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis. Photophysical properties of the core-shell NPs were determined from ultraviolet-visible absorption spectroscopy (UV-Vis) and photoluminescence spectroscopy (PL). For core-shell NPs produced via two-pots method only CuTe@PPI exhibited ? ? ?* and n ? ?* which indicate that CuSb@PPI produced via two-pots method was unsuccessfully synthesized. The ? ? ?* and n ? ?* transitions indicate the presence of polypropylenimine tetra(5-(2-thienyl) salicylaldimine) (PPI) on the surface of CuTe NPs and CuSb NPs. FTIR confirmed coordination of PPI on the surface of CuTe NPs and CuSb NPs by showing a shift in wavenumber of C=N group bands from PPI. HR-TEM showed that the CuTe@PPI synthesized via one-pot method have a wide particles sizes distribution with an average particles size of 13.60 nm while for CuTe@PPI synthesized via two-pots it was impossible to determine the particles size due to aggregation. CuSb@PPI synthesized via twopots method and one-pot method has a wide particles sizes distribution with an average size of 7.98 nm and 11.61 nm respectively. The average particles sizes determined by HR-SEM were found to be 35.24 nm (CuTe@PPI two-pots method), 33.90 nm (CuTe@PPI one-pot method), 18.30 nm (CuSb@PPI two-pots method), and 16.18 nm (CuSb@PPI one pot method).
2021-08-31
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Pickering, Jon W. « Applications of Optical Properties from Nanomaterials for Enhanced Activity of a Titania Photocatalyst under Solar Radiation ». Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5760.

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In recent years, employing advanced oxidation processes (AOPs) as a means of wastewater remediation has emerged as a promising route towards maintaining a sustainable global water management program. The heterogeneous photocatalytic oxidation process has been of particular interest due to the prospective of utilizing solar radiation as the driving force behind the degradation of pollutants. Of the photocatalyst studied to date, TiO2 remains the most attractive material for environmental applications due to its affordability, stability, biocompatibility and high quantum yield. A key draw back however is roughly only 5% of solar radiation incident on earth can provide the energy required (3.0-3.2 eV) to generate the electron-hole pairs necessary for photo-oxidation. As a means to improve the process under solar irradiance, optical properties such as surface plasmon resonance of metallic nanoparticles and upconversion luminescence of rare earth ions have been exploited for improved light harvesting as well as the generation of more usable UV light from lower energy photons. In order to explore these phenomena and their role in the enhancement of this AOP, the photocatalytic degradation of organic dyes was studied under various conditions employing Degussa P25 TiO2 as the photocatalyst. Ag nanocubes, Ag-Pd core-shell nanoparticles and YAG:Yb+3,Er+3 served as the dopants for the various studies which resulted in enhanced degradation rates, insight into the applicability of utilizing Yb+3 as sensitizing ion under solar radiation and a novel core-shell nanoparticle synthesis.
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De, Silva Vashista C. « Core-Shell Based Metamaterials : Fabrication Protocol and Optical Properties ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062904/.

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The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports our experiments and indicates that light goes mostly through the epsilon-near-zero shell with approximately wavelength independent absorption rate. Broadband extinction in fractal shells allows as well for a laser photoburning of holes in the extinction spectra and consequently windows of transparency in a controlled manner. Au fractal nanostructures grown on PCC flakes provide the highest mass normalized extinction, up to 3 m^2/g, which has been demonstrated in the broad spectral range. In the nanoplasmonic field active devices consist of a Au nanoparticle that acts as a cavity and the dye molecules attached to it via thin silica shell as the active medium. Such kind of devices is considered as a nano-laser or nano-amplifier. The fabricated nanolasers were studied for their photoluminescence kinetic properties. It is shown that the cooperative effects due to the coupling of dye molecules via Au nanoparticle plasmons result in bi-exponential emission decay characteristics in accord with theory predictions. These bi-exponential decays involve a fast superradiant decay, which is followed by a slow subradiant decay. To summarize, this work shows new attractive properties of core-shell nanoparticles. Fractal Au shells on silica cores prove to be a good scattering suppressor and a band pass filter in a broadband spectral range. They can also be used as an obscurant when PCC is used as the core material. Finally, gold nanoparticles coated with silica with dye results in bi-exponential decays.
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Etschel, Sebastian Heinrich [Verfasser], et Marcus [Gutachter] Halik. « Hierarchical assemblies of core-shell nanomaterials by the Huisgen-1,3-dipolar cycloaddition / Sebastian Heinrich Etschel ; Gutachter : Marcus Halik ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1123284342/34.

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Ban, Zhihui. « Synthesis and investigation of nanomaterials by homogeneous nonaqueous solution phase reactions ». ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,274.

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Thesis (Ph. D.)--University of New Orleans, 2005.
Title from electronic submission form. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry"--Dissertation t.p. Vita. Includes bibliographical references.
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Sanderyd, Viktor. « Novel Hybrid Nanomaterials : Combining Mesoporous Magnesium Carbonate with Metal-Organic Frameworks ». Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355366.

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Nanotechnology as a field has the potential to answer some of the major challenges that mankind faces in regards to environmental sustainability, energy generation and health care. Though, solutions to these concerns can not necessarily rely on our current knowhow. Instead, it is reasonable to expect that humanity must adapt and learn to develop new materials and methods to overcome the adversities that we are facing. This master thesis has involved developing novel materials, serving as a small step in the continuous march towards a bright future where this is possible. More specifically, this work sought to combine mesoporous magnesium carbonate with various metal-organic frameworks to utilize the beneficial aspects from each of these constituents. The ambition was that these could be joined to render combined micro-/mesoporous core-shell structures, with high surface areas and many active sites whilst maintaining a good permeability. Numerous different synthesis routes were developed and explored in the pursuit of viable routes to design novel materials with potential future applications within for instance drug delivery, water harvesting from air and gas adsorption. Coreshell structures of the hydrophilic mesoporous magnesium carbonate covered with the hydrophobic zeolitic imidazole framework ZIF-8 was successfully synthesized for the first time, and practical studies demonstrated a dramatically enhanced water stability, which is perceived to have an impact on further research on these materials. ZIF-67 was also combined with mesoporous magnesium carbonate in a similar manner. Further, Mg-MOF-74 was grown directly from mesoporous magnesium carbonate, where the latter acted as a partially self-sacrificing template, with the aim of rendering a porous hierarchical structure with contributions from the micro- and mesoporous ranges. The outcomes of all these syntheses were characterized using several analyzing methods such as scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and nitrogen sorption analysis.
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Tripathy, Jagnyaseni. « Template-Assisted Fabrication of Ferromagnetic Nanomaterials ». ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1951.

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Abstract Template assisted deposition was used to produce various nanomaterials including simple nanowires, nanorods, multi-segmented metal nanowires, core-shell nanowires, alloy and polymer wires and tubes. Anodized aluminum oxide (AAO) membranes were used as templates for the growth of the various structures using an electrochemical deposition method and also by wetting the porous templates. In the electrochemical deposition method, the pore size of the templates affects the rate of synthesis and the structures of the nanomaterials while in the wetting method, the viscosity and reaction time in the polymer solution influence the structures of the nanomaterials. A conventional two-step anodization procedure was used to synthesize thick AAO templates with porous hexagonal channels at a constant applied voltage and temperature. A maximum thickness of over 180 µm oxide layer could be fabricated using mild anodization at 60 V and 80 V. Compared to conventional mild anodization, these conditions facilitated faster growth of oxide layers with regular pore arrangement. Polyethylene glycol (PEG) containing ferromagnetic nanowires were synthesized using template assisted electrochemical deposition method. During the synthesis, simultaneous deposition of polymer and metal ions resulted nanowires coated with a uniform layer of PEG without interfering with the structure and magnetic properties of the nanowires. PEG-coated Ni nanowires were embedded in polyethylene diacrylate (PEGDA) matrix after the removal of the AAO templates. Comparison of results with and without a magnetic field during embedding showed that the presence of magnetic field supported embedding of nanowire arrays in polymer. Influence of using AAO templates with several pore diameters for the synthesis of bimetallic nanowires were studied by growing Ni-Fe and Ni-Co bi-metallic nanowires. At a constant applied current by using templates with a pore diameters of 60 nm alloy formed while with a pore diameter of 130 nm core-shell nanowires formed. Polyvinylidene fluoride (PVDF) films and nanotubes were synthesized using a solution recrystallization method that favored the formation of piezoelectric β phase thin films. Variation in the concentration of polymer in the mixture solution allowed synthesis of different types of structures such as PVDF composites, nanorods and nanocrystals with tunable morphologies. Keywords: One-dimensional structures, electrodeposition, porous alumina, ferromagnetic nanostructures, magnetic core-shell nanowires, alloys, polymer composite, stimuli-active, PEGDA, azobenzene, and PVDF.
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Fairclough, Simon Michael. « Carrier dynamics within semiconductor nanocrystals ». Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:857f624d-d93d-498d-910b-73cce12c4e0b.

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This thesis explores how the carrier dynamics within semiconductor nanocrystals can be directly engineered through specific core-shell design. Emphasis is placed on how material characteristics, such as strain or alloying at a core-shell interface, can influence the exciton energies and the recombination dynamics within semiconductor nanocrystals. This study synthesises type-II heterojunction ZnTe/ZnSe core-shell nanocrystals via a diethyl zinc-free synthesis method, producing small size distributions and quantum yields as high as 12%. It was found that the 7% lattice mismatch between the core and shell materials places limitations on the range of structures in which coherent growth is achieved. By developing compositional and strained atomistic core-shell models a variety of physical and optical properties could be simulated and has led to a clear picture of the core-shell architecture to be built. This characterisation provides evidence that the low bulk modulus ZnTe cores are compressed by the higher bulk modulus smaller lattice constant ZnSe shells. Further studies show how strain is manifested in structures with 'sharp' core-shell interfaces and how intentional alloying the interface can influence the growth and exciton energies. A (2-6)-band effective mass model was able to distinguish between the as-grown 'sharp' and 'alloyed' interfaces which indicated that strain accentuates the redshift of the excitonic state whilst reduced strain within an alloyed interface sees a reduced redshift. Single nanocrystal spectroscopy investigations of brightly emitting single graded alloyed nanocrystals and of a size series of commercially available CdSe/ZnS nanocrystals showed almost no fluorescence intermittency (nearly 'non-blinking'). These investigations also identified trion recombination as the main mechanism within the blinking 'off' state. Ultimately this thesis adds to the growing understanding of how specific core-shell architectures manipulate the electronic structure and develops techniques to identify specific material characteristics and how these characteristics influence the physical and optical properties within semiconductor nanocrystals.
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Sourice, Julien. « Synthèse de nanocomposites cœur-coquille silicium carbone par pyrolyse laser double étage : application à l’anode de batterie lithium-ion ». Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112166/document.

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Le remplacement du carbone graphite, matériau commercial dans les batteries au lithium ion, par du silicium est un axe privilégié afin d’augmenter la capacité des anodes au sein de ces accumulateurs. En revanche, le silicium micrométrique souffre de puissants effets de dégradation au cours du cyclage. L’expansion volumique des particules lors de la formation des alliages lithiés et la réduction des électrolytes en contact avec la matière active, sous forme de produits de dégradation appelés SEI, induisent une diminution importante de la durée de vie de ces anodes. La communauté scientifique a donc émis l’idée de stabiliser le silicium en diminuant la taille des particules à l’échelle nanométrique, limitant fortement le risque de pulvérisation. De plus, le contact direct entre la matière active et les solvants peut être très largement diminué via la formation d’une coquille de carbone autour des particules de silicium. La problématique est alors la suivante : obtenir un matériau dit « cœur-coquille » à base de silicium nanométrique enrobé de carbone, à l’aide d’un procédé facilement industrialisable.Le Laboratoire Edifices Nanométriques (LEDNA) possède une grande expertise en synthèse de nanomatériaux par pyrolyse laser en phase gaz. Cette méthode de synthèse est souple, possède un rendement de production élevé et offre un contrôle important sur les conditions de réaction. Afin de répondre à la problématique posée, un nouveau réacteur de synthèse à deux étages de réaction a été développé. A l’aide de cette expérience originale, des nanomatériaux à base de silicium cristallin ont été synthétisés, ainsi que leur équivalent enrobé de carbone. Des cœurs de silicium amorphes ont également été enrobé de carbone, permettant l’obtention d’une structure cœur-coquille encore inédite dans la littérature. La microscopie révèle que les matériaux sont sous forme de chainette de particules, une structure obtenue de façon classique par les méthodes de synthèse en phase gaz mais qui se pourrait se révéler bénéfique aux propriétés de conduction électronique et ionique. Les coquilles carbonées caractérisées par spectroscopie Raman révèlent une organisation riche en liaisons sp2 mais peu graphitique. Une étude par spectroscopie des électrons Auger (AES) montre que l’homogénéité de l’enrobage carboné varie selon les matériaux, les plus petits cœurs de silicium bénéficiant d’un meilleur recouvrement. Par diffraction des neutrons, nous avons montré que le silicium amorphe enrobé est très peu sensible à l’oxydation contrairement aux autres matériaux non enrobés.Les matériaux ont été utilisés en tant que matériaux d’anode dans des batteries au lithium métal. Une étude par balayage voltamétrique a montré que les matériaux à base de silicium cristallin nécessitent plusieurs balayages avant d’être lithiés jusqu’au cœur. En revanche, le silicium amorphe enrobé subit une lithiation profonde immédiate, phénomène dont la littérature ne fait pas mention faute de pouvoir obtenir ce composite non oxydée selon les méthodes de synthèses traditionnelles. Une étude par spectroscopie d’impédance électrochimique résolue en potentiel a été réalisée afin de déterminer les mécanismes de dégradation de ces électrodes. Nous avons montré que ce phénomène est principalement entretenu par la dissolution des composés de la SEI lors de la délithiation des matériaux. De plus, l’intensité de ce phénomène de dissolution semble corrélée avec la quantité de surface de silicium potentiellement en contact avec l’électrolyte. Enfin, testés galvanostatiquement, les matériaux enrobés de carbone ont démontré des performances très supérieures au carbone graphite. Au régime élevé de 2C, difficilement accessible au matériau d’anode commerciale, le matériau amorphe enrobé a supporté près de 500 cycles en maintenant une capacité et une efficacité coulombique élevée, supérieure à 800 mAh.g-1 et 99,99%
The replacement of carbon graphite, the commercial anode material in Li-ion batteries, by silicon is one of the most promising strategies to increase the capacity of anode in these devices. However, micrometric silicon suffers from strong degradation effect while cycling. The volume expansion of the lithiated particles and the direct contact between the active material and the solvents induce the continuous formation and pulverization of a solid electrolyte interphase (SEI) leading to the rapid fading of the capacity. Many research groups suggest decreasing the size of the particle to the nanoscale where pulverization of the particles is almost inexistent. Furthermore, the formation of a carbon shell around these silicon nanoparticles is cited as the most efficient way to isolate the material from the direct contact with the solvent. The main issue is to obtain these core shell nanocomposites with a process able to meet industrial requirement.The Nanometric Structure Laboratory (LEDNA) is experimented in the synthesis of nanomaterial thanks to the gas phase laser pyrolysis method. This versatile process is characterized by a high yield of production and permits an efficient control over the reaction parameters. In order to obtain core shell structures, a new reactor has been developed by the combination of two stages of reaction. Thanks to this original setup, crystalline silicon cores covered or not with a carbon shell were achieved in one step for the first time. Likewise, amorphous cores were covered with a carbon shell, leading to the synthesis of a novel nanocomposite. Microscopic study reveals that these materials are obtained in a chain-like structure that can be beneficial to the electronic and ionic conduction properties. The carbonaceous compound were characterized by Raman spectroscopy and appeared to be non-graphitic sp2 rich species known in the literature as basic structural units (BSU). Auger electron spectroscopy study highlights the homogeneity of the carbon covering, in particular over smaller silicon cores. Neutron diffraction showed that the amorphous silicon cores covered with carbon are protected against passive oxidation unlike bare amorphous cores.The nanocomposites were used as anode materials in lithium-metal coin cell configuration. A cyclic voltammetry study highlights that crystalline silicon cores embedded into carbon need many sweeps before their full lithiation whereas amorphous core shell nanocomposites deeply lithiated from the first sweep, a phenomena yet not described in the literature. A potential resolved electronic impedance spectroscopy technic was used to determine the main degradation process of the core shell materials. We showed that the capacity fading can be mainly attributed to SEI dissolution and reformation through cycling, obstructing the porous structure of the electrode and limiting the cyclability. Finally, galvanostatically tested the core-shell nanocomposites reveal enhanced performance compared to graphite carbon. At the high charge/discharge rate of 2C, hardly reachable to the commercial anode material, the amorphous core-shell nanocomposite was cycled up to 500 cycles while maintaining a high capacity of 800 mAh.g-1 and outstanding coulombic efficiency of 99,99 %
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Chapitres de livres sur le sujet "Core-shell Nanomaterials"

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Ray, Mallar, Sayak Dutta Gupta et Atrayee Hazra. « Silicon-based core–shell nanostructures ». Dans Silicon Nanomaterials Sourcebook, 215–62. Boca Raton, FL : CRC Press, Taylor & Francis Group, [2017] | Series : Series in materials science and engineering : CRC Press, 2017. http://dx.doi.org/10.4324/9781315153551-11.

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Contreras-García, Angel, Guillermina Burillo et Emilio Bucio. « Polymeric Nano-, Micellar and Core-shell Materials ». Dans Intelligent Nanomaterials, 317–45. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118311974.ch8.

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Bailey, R. E., et S. Nie. « Core-Shell Semiconductor Nanocrystals for Biological Labeling ». Dans The Chemistry of Nanomaterials, 405–17. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/352760247x.ch12.

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Skoropata, Elizabeth, et Johan van Lierop. « Characterization of Magnetism in Core–Shell Nanoparticles ». Dans Magnetic Characterization Techniques for Nanomaterials, 375–412. Berlin, Heidelberg : Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-52780-1_11.

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Wang, Yiqian, et Chao Wang. « TEM for Characterization of Core-Shell Nanomaterials ». Dans Transmission Electron Microscopy Characterization of Nanomaterials, 243–85. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-38934-4_6.

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Tsavalas, John G. « Emulsion Copolymerization (Also Leading to Core-Shell Structures) ». Dans Encyclopedia of Polymeric Nanomaterials, 1–10. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-36199-9_346-1.

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Tsavalas, John G. « Emulsion Copolymerization (Also Leading to Core-Shell Structures) ». Dans Encyclopedia of Polymeric Nanomaterials, 695–704. Berlin, Heidelberg : Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-29648-2_346.

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Yang, Jun, et Hui Liu. « Cadmium Selenide–Platinum Nanocomposites with a Core–Shell Construction ». Dans Metal-Based Composite Nanomaterials, 115–41. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-12220-5_5.

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Lee, Hwanbum, Jae Yeon Kim, Eun Hee Lee, Young In Park, Keun Sang Oh, Kwangmeyung Kim, Ick Chan Kwon et Soon Hong Yuk. « Core/Shell Nanoparticles for Drug Delivery and Diagnosis ». Dans Nanomaterials in Drug Delivery, Imaging, and Tissue Engineering, 321–43. Hoboken, NJ, USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118644591.ch9.

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Chen, Feng, et Weibo Cai. « Chapter 16. Recent Advances in The Engineering of Silica-Based Core@Shell Structured Hybrid Nanoparticles ». Dans Hybrid Nanomaterials, 415–38. 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 : CRC Press, 2016. http://dx.doi.org/10.1201/9781315370934-17.

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Actes de conférences sur le sujet "Core-shell Nanomaterials"

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I. V., Chepkasov, et Dzhamalkhanova A. M. « The Study of Thermodynamic Properties of Nanoparticles "Core-shell" Cu@Si ». Dans NANOMATERIALS AND TECHNOLOGIES-VI. Buryat State University Publishing Department, 2016. http://dx.doi.org/10.18101/978-5-9793-0883-8-210-213.

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Myronyuk, Iryna, Alexander Pud, Andrew Mamykin et Alexander Kukla. « The specificity of the core-shell polyvinylidene/polyaniline nanocomposite sensing applications ». Dans 2017 IEEE 7th International Conference "Nanomaterials : Application & Properties" (NAP). IEEE, 2017. http://dx.doi.org/10.1109/nap.2017.8190266.

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Sharma, M., D. K. Gupta, R. K. Pandey, P. K. Giri, D. K. Goswami, A. Perumal et A. Chattopadhyay. « ZnS∕CdS Core∕Shell Nanostructures For Light Emission in Blue Region ». Dans INTERNATIONAL CONFERENCE ON ADVANCED NANOMATERIALS AND NANOTECHNOLOGY (ICANN-2009). AIP, 2010. http://dx.doi.org/10.1063/1.3504347.

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Mumin, Md Abdul, Kazi Farida Akhter et Paul A. Charpentier. « Photo-physical properties enhancement of bare and core-shell quantum dots ». Dans ELECTRONIC, PHOTONIC, PLASMONIC, PHONONIC AND MAGNETIC PROPERTIES OF NANOMATERIALS. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4870227.

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Baslak, Canan, Ozcan Koysuren et Mahmut Kus. « Electrospun nanofibers with CdTe QDs, CdTeSe QDs and CdTe/CdS core-shell QDs ». Dans 2017 IEEE 7th International Conference "Nanomaterials : Application & Properties" (NAP). IEEE, 2017. http://dx.doi.org/10.1109/nap.2017.8190290.

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Dalela, Manu, Harpal Singh, Udit Soni et Sameer Sapra. « Tumor cell targetting using folate conjugated core/shell CdSe/CdS/ZnS nano rods ». Dans International Conference on Advanced Nanomaterials & Emerging Engineering Technologies (ICANMEET-2013). IEEE, 2013. http://dx.doi.org/10.1109/icanmeet.2013.6609261.

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Holovatsky, Volodymyr, Maryna Chubrei et Volodymyr Ivanko. « Optical Absorption in Core-Shell Quantum Antidot with Donor Impurity under Applied Magnetic Field ». Dans 2021 IEEE 11th International Conference Nanomaterials : Applications & Properties (NAP). IEEE, 2021. http://dx.doi.org/10.1109/nap51885.2021.9568536.

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Shyrokorad, D. V., et G. V. Kornich. « The influence of bombarding particle size on the intensity of the core-shell cluster formation ». Dans 2017 IEEE 7th International Conference "Nanomaterials : Application & Properties" (NAP). IEEE, 2017. http://dx.doi.org/10.1109/nap.2017.8190158.

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Holovatsky, V., M. Yakhnevych et M. Chubrei. « Effect of Electric and Magnetic Field on Electron Energy Spectrum in Core-Shell Quantum Dot ». Dans 2018 IEEE 8th International Conference Nanomaterials : Application & Properties (NAP). IEEE, 2018. http://dx.doi.org/10.1109/nap.2018.8915140.

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Shyrokorad, D. V., et G. V. Kornich. « Formation of the Core-Shell Structures from Janus-Like Nanoclusters Under Low-Energy Argon Particles Impacts ». Dans 2018 IEEE 8th International Conference Nanomaterials : Application & Properties (NAP). IEEE, 2018. http://dx.doi.org/10.1109/nap.2018.8915306.

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