Academic literature on the topic 'Nanoparticule anisotrope'
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Journal articles on the topic "Nanoparticule anisotrope"
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Capek, Ignác. "Noble Metal Nanoparticles and Their (Bio) Conjugates. II. Preparation." International Journal of Chemistry 8, no. 1 (January 6, 2016): 86. http://dx.doi.org/10.5539/ijc.v8n1p86.
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Hybrid nanoparticles of gold and silver can not only retain the beneficial features of both nanomaterials, but also possess unique advantages (synergism) over the other two types. Novel pseudospherical and anisotropic nanoparticles, bimetallic triangular nanoparticles, and core@shell nanoparticles were prepared by the different procedures for various applications and understanding both the particle evolution (nucleation) and nanoparticle anisotropy. Hybrid nanoparticles of gold and silver are considered to be low in toxicity, and exhibit facile surface functionalization chemistry. Furthermore, their absorption peaks are located in visible and near-infrared region. These nanoparticles provide significant plasmon tunability, chemical and surface modification properties, and significant advances in the growth into anisotropic nanostructures. The photoinduced synthesis can be used to prepare various (sub) nanoparticles and OD and 1D nanoparticles. Ostwald and digestive ripening provided narrower particle size distribution.
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Kijima-Aoki, Hanae, Yasushi Endo, Takamichi Miyazaki, Tsutomu Nojima, Kenji Ikeda, Nobukiyo Kobayashi, Shigehiro Ohnuma, and Hiroshi Masumoto. "Shape effect of Co nanoparticles on the electric and magnetic properties of Co–SiO2 nanogranular films." AIP Advances 12, no. 3 (March 1, 2022): 035229. http://dx.doi.org/10.1063/9.0000310.
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Controlling the magnetic anisotropy of nanoparticles is a crucial but challenging step for developing new magnetic functions. Here, we demonstrate a simple approach to controlling the shape of Co nanoparticles in a Co-SiO2 nanogranular film from oblate to prolate spheroid by varying the substrate rotation speed during the tandem fabrication process without changing the film composition (Co:SiO2 = 3:7). Changing the nanoparticles from oblate to prolate, increasing perpendicular length of ellipsoidal nanoparticles, changes the magnetic anisotropy axis of Co–SiO2 nanogranular films from in-plane to out-of-plane, which indicates that the shape anisotropy profoundly affects the magnetic properties. Despite the small tunneling current of a few tens of nanoamperes, a maximum tunneling magnetoresistance effect of up to 2.8 % was realized under an applied magnetic field of 12 kOe in the film plane. Achieving both in-plane and perpendicular spin-dependent tunneling, the anisotropic nanogranular films imply direction controllable tunneling materials as future topological nanoarchitecture. Such high-resistivity nanogranular films with a controllable magnetic nanoparticle shape facilitate the design of new magneto-optical devices with high withstand voltages.
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Quevedo, Daniel F., Cody J. Lentz, Adriana Coll de Peña, Yazmin Hernandez, Nahal Habibi, Rikako Miki, Joerg Lahann, and Blanca H. Lapizco-Encinas. "Electrokinetic characterization of synthetic protein nanoparticles." Beilstein Journal of Nanotechnology 11 (October 13, 2020): 1556–67. http://dx.doi.org/10.3762/bjnano.11.138.
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The application of nanoparticle in medicine is promising for the treatment of a wide variety of diseases. However, the slow progress in the field has resulted in relatively few therapies being translated into the clinic. Anisotropic synthetic protein nanoparticles (ASPNPs) show potential as a next-generation drug-delivery technology, due to their biocompatibility, biodegradability, and functionality. Even though ASPNPs have the potential to be used in a variety of applications, such as in the treatment of glioblastoma, there is currently no high-throughput technology for the processing of these particles. Insulator-based electrokinetics employ microfluidics devices that rely on electrokinetic principles to manipulate micro- and nanoparticles. These miniaturized devices can selectively trap and enrich nanoparticles based on their material characteristics, and subsequently release them, which allows for particle sorting and processing. In this study, we use insulator-based electrokinetic (EK) microdevices to characterize ASPNPs. We found that anisotropy strongly influences electrokinetic particle behavior by comparing compositionally identical anisotropic and non-anisotropic SPNPs. Additionally, we were able to estimate the empirical electrokinetic equilibrium parameter (eE EEC) for all SPNPs. This particle-dependent parameter can allow for the design of various separation and purification processes. These results show how promising the insulator-based EK microdevices are for the analysis and purification of clinically relevant SPNPs.
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Belim, Sergey V. "Study of ordering in 2D ferromagnetic nanoparticles arrays: Computer simulation." AIMS Materials Science 10, no. 6 (2023): 948–64. http://dx.doi.org/10.3934/matersci.2023051.
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<abstract> <p>This article describes ordering in a 2D ferromagnetic nanoparticles array by computer simulation. The Heisenberg model simulates the behavior of spins in nanoparticles. Nanoparticles interact using dipole-dipole forces. Computer simulations use the Monte Carlo method and Metropolis algorithm. Two possible types of ordering for the nanoparticles' magnetic moments are detected in the system. The magnetic anisotropy direction for the nanoparticles determines the type of ordering. If the anisotropy direction is oriented perpendicular to the substrate plane, then a superantiferromagnetic phase with staggered magnetization is realized. If the magnetic anisotropy is oriented in the nanoparticle plane, the superantiferromagnetic phase has a different structure. The nanoparticle array is broken into chains parallel to the anisotropy orientations. In one chain of nanoparticles, magnetic moments are oriented in the same way. The magnetic moments of the nanoparticles are oriented oppositely in neighbor chains. The temperature of phase transitions is calculated based on finite dimensional scaling theory. Temperature depends linearly on the intensity of the dipole-dipole interaction for both types of superantiferromagnetic transition.</p> </abstract>
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Bayram, Serene S., Klas Lindfors, and Amy Szuchmacher Blum. "Tunable longitudinal modes in extended silver nanoparticle assemblies." Beilstein Journal of Nanotechnology 7 (August 26, 2016): 1219–28. http://dx.doi.org/10.3762/bjnano.7.113.
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Nanostructured materials with tunable properties are of great interest for a wide range of applications. The self-assembly of simple nanoparticle building blocks could provide an inexpensive means to achieve this goal. Here, we generate extended anisotropic silver nanoparticle assemblies in solution using controlled amounts of one of three inexpensive, widely available, and environmentally benign short ditopic ligands: cysteamine, dithiothreitol and cysteine in aqueous solution. The self-assembly of our extended structures is enforced by hydrogen bonding. Varying the ligand concentration modulates the extent and density of these unprecedented anisotropic structures. Our results show a correlation between the chain nature of the assembly and the generation of spectral anisotropy. Deuterating the ligand further enhances the anisotropic signal by triggering more compact aggregates and reveals the importance of solvent interactions in assembly size and morphology. Spectral and morphological evolutions of the AgNPs assemblies are followed via UV–visible spectroscopy and transmission electron microscopy (TEM). Spectroscopic measurements are compared to calculations of the absorption spectra of randomly assembled silver chains and aggregates based on the discrete dipole approximation. The models support the experimental findings and reveal the importance of aggregate size and shape as well as particle polarizability in the plasmon coupling between nanoparticles.
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Usov, Nikolai A., Mikhail S. Nesmeyanov, Elizaveta M. Gubanova, and Natalia B. Epshtein. "Heating ability of magnetic nanoparticles with cubic and combined anisotropy." Beilstein Journal of Nanotechnology 10 (January 29, 2019): 305–14. http://dx.doi.org/10.3762/bjnano.10.29.
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The low frequency hysteresis loops and specific absorption rate (SAR) of assemblies of magnetite nanoparticles with cubic anisotropy are calculated in the diameter range of D = 20–60 nm taking into account both thermal fluctuations of the particle magnetic moments and strong magneto–dipole interaction in assemblies of fractal-like clusters of nanoparticles. Similar calculations are also performed for assemblies of slightly elongated magnetite nanoparticles having combined magnetic anisotropy. A substantial dependence of the SAR on the nanoparticle diameter is obtained for all cases investigated. Due to the influence of the magneto–dipole interaction, the SAR of fractal clusters of nanoparticles decreases considerably in comparison with that for weakly interacting nanoparticles. However, the ability of magnetic nanoparticle assemblies to generate heat can be improved if the nanoparticles are covered by nonmagnetic shells of appreciable thickness.
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Wang, Xujie, Zhenlong Dou, Chi Zhang, FangFang Deng, XiaoLin Lu, ShuangShuang Wang, Li Zhou, and Tao Ding. "Polarization-controlled anisotropy in hybrid plasmonic nanoparticles." Nanophotonics 11, no. 5 (January 27, 2022): 1003–9. http://dx.doi.org/10.1515/nanoph-2021-0691.
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Abstract Anisotropy has played a critical role in many material systems, but its controllable creation and modulation have been a long-lasting challenge for the scientific communities. Polarization-addressed anisotropy appears more attractive among all approaches due to its excellent controllability, simplicity, and accuracy, but only a limited number of material systems are applicable for such a concept, which are largely focused on oriented growth. Here, we establish a polarization-dependent anisotropic etching system made of Au@oligomer core–shell nanoparticles (NPs). As the oligomer coatings can be photochemically degraded via two-photon photolithography, the plasmonic near-field enhancement supported by the Au NP cores renders much faster degradation of the oligomer shells along the polarization, resulting in anisotropic Au@oligomer hybrid NPs. Such shape anisotropy leads to polarization-dependent photoluminescence with embedded dyes of methylene blue, which can be used as single-particle-based polarization detector. The oligomer lobes capped at the sides of the Au NP can also function as a protection agent for anisotropic photochemical growth of Au NPs, which evolve into Au nanorods and mushrooms with controlled irradiation time. Such polarization-directed etching of oligomer shells has unique advantages of high local-selectivity, controllability, and versatility for on-chip nanofabrication, which opens many new opportunities for integrated nanophotonic devices.
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Khan, I., C. Howell, T. L. McGinnity, L. Li, R. K. Roeder, and A. J. Hoffman. "Effects of anisotropy, morphology, and interparticle coupling on the far-infrared optical modes of randomly oriented ZnO nanoparticles." Applied Physics Letters 122, no. 4 (January 23, 2023): 041104. http://dx.doi.org/10.1063/5.0128493.
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Polar dielectric nanoparticles (NPs) with uniaxial anisotropy support two-surface phonon polariton modes inside a reststrahlen band. The effective permittivity of a randomly orientated ensemble of NPs is usually assumed to be isotropic due to averaging of the optical response over all orientations. In this work, we demonstrate that this assumption is not valid for ZnO nanoparticles, and the resultant absorption of a nanoparticle film can be tailored by the nanoparticle morphology. We measure distinct features in the absorption spectrum for films or ensembles of interacting polar dielectric NPs, which we attribute to the excitation of SPhP modes due to anisotropy in the dielectric permittivity of the NPs. We identify and characterize these modes in elliptical and rod-like ZnO NPs prepared by solvothermal synthesis and dispersed within an optically transparent matrix. Localized optical modes are identified using Fourier transform infrared absorption spectroscopy and confirmed by finite element simulations. The broadening and maxima of the modes are shown to be governed by the effects of anisotropy, nanoparticle morphology, and interparticle coupling within nanoparticle ensembles.
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Osipov, Mikhail A., Alexey S. Merekalov, and Alexander A. Ezhov. "Statistical Theory of Helical Twisting in Nematic Liquid Crystals Doped with Chiral Nanoparticles." Crystals 11, no. 11 (November 22, 2021): 1432. http://dx.doi.org/10.3390/cryst11111432.
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A molecular field theory of the cholesteric ordering in nematic nanocomposites doped with chiral nanoparticles was developed taking into consideration chiral dispersion interaction between rod-like nanoparticles. It was shown that the inverse pitch of the cholesteric helical structure is proportional to the anisotropy of the effective polarizability and the anisotropy of the effective gyration tensor of a nanoparticle in the nematic host. The theory enables one to predict the helical sense inversion induced by a change of the low-frequency dielectric susceptibility of the nematic host phase. The components of the high-frequency effective polarizability and the effective optical activity of a gold rod-like nanoparticle in a particular nematic solvent were calculated numerically.
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Afremov, Leonid L., Tatyana N. Gnitetskaya, and Elena B. Ivanova. "On the Calculation of Effective Anisotropy Constant of Nanoparticle." Advanced Materials Research 734-737 (August 2013): 2310–13. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.2310.
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A correct composition of two kind of magnetic anisotropy of ellipsoidal nanoparticles: crystalline anisotropy and shape anisotropy - has been carried out. It was shown that according to the shape anisotropy the effective anisotropy constant can change non-monotonically. The temperature dependence of effective anisotropy constant on the angle defining the position of effective axis was calculated. It was found out if the angle between the crystalline anisotropy axis and the long axis of nanoparticle exceedsπ/4, then the effective constant as well as the position of effective axis has to change non-monotonically according to changing of temperature.
Dissertations / Theses on the topic "Nanoparticule anisotrope"
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Bernand-Mantel, Anne. "Transport à un électron et effets magnéto-Coulomb dans une nanoparticule unique." Paris 6, 2008. http://www.theses.fr/2008PA066015.
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"Cette thèse s'inscrit dans le cadre de l'évolution récente de la spintronique en basse dimension : la nanospintronique. L'objectif de cette thèse a été l'étude expérimentale de l'interaction entre magnétisme et transport à un électron, nommément effets magnéto-Coulomb, dans des nanostructures magnétiques contenant des nanoparticules uniques. En utilisant une technique de nanoindentation résistivo-contrôlée développée au laboratoire, de tels échantillons constitués d'une nanoparticule métallique (or, cuivre ou aluminium) de quelques nanomètres de diamètre, reliée via des barrières tunnel d'alumine à des électrodes de cobalt ont été élaborés. Les échantillons ont présenté les caractéristiques typiques attendue du transport à un électron (effet de blocage de Coulomb) à travers une nanoparticule unique. De fortes magnéto-résistances ont été observées. Des effets de transport dépendant du spin et d'accumulation de spin liés à une augmentation du temps de vie du spin dans les nanoparticules métalliques ont été mis en évidence. De plus, un autre mécanisme de magnéto transport, ayant pour origine l'anisotropie magnétique de l'électrode et agissant comme une "grille" sur l'îlot, a été observé. "
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Moukarzel, Waêl. "Synthèse et caractérisation de glycosilicones et leur application à la préparation et stabilisation de nanoparticules d'or." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1628/.
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Le couplage d'une chaîne siloxane avec des groupements fonctionnels divers donne accès à des polymères aux propriétés originales couplant la flexibilité de la chaîne avec les propriétés des groupes fonctionnels. Dans cet état d'esprit, nous avons souhaité étudier le couplage de groupements de type saccharidiques aux chaînes de polysiloxane. Dans une première partie de ces travaux de thèse, une nouvelle méthode rapide, douce et efficace a été mise au point pour la préparation de polysiloxanes linéaires ou hyperbranchés à groupements saccharidiques, en position latérale ou terminale. La préparation se fait sans utilisation de groupements protecteurs de sucres, permettant ainsi d'éviter les conditions usuelles acides ou basiques de déprotection et de conserver ainsi l'intégralité des chaînes siloxanes avant et après greffage des sucres. Les polymères ont été caractérisés par RMN 1H, 13C, 29Si, IR et Chromatographie d'Exclusion Stérique. Ces " glycosilicones", à taux de greffage et masses modulables à volonté, ont servi par la suite à stabiliser efficacement des nanoparticules d'or préformées en solution aqueuse y compris à des forces ioniques élevées. Les propriétés réductrices d'amino-sucres utilisés au cours de cette thèse pour la synthèse des glycosilicones ont été mises à profit afin de réaliser la synthèse directe de nanoparticules dans des conditions plus douces que les méthodes de synthèse classique (telle que la réduction de sel d'or avec du borohydrure de sodium). Ces amino-sucres (glucosamine, glucamine) jouent le rôle à la fois de réducteurs, de stabilisants en milieu aqueux. L'avantage de cette méthode réside également en l'utilisation d'un réactif unique non toxique en vue de l'utilisation de ces nanoparticules dans des tests biologiques. La méthode de synthèse se fait en une seule étape et à température ambiante et aboutit à la formation de nanoparticules sphériques avec un bon rendement, mais également, induit des croissances anisotropes conduisant à l'obtention de nanoparticules en forme d'étoiles ou multi-branches avec des rendements très élevés. La taille et le nombre de branches des nano-étoiles ont été modulés en ajustant les conditions expérimentales. Elles ont été caractérisées du point de vue de leur morphologie, stabilité et propriétés optiques (résonance plasmon) par microscopie électronique et spectroscopie UV-visibleCoupling a siloxane chain with various functional groups leads to polymers with new properties combining the flexibility of the chain with the properties of the functional groups. Accordingly, we wanted to study the grafting of saccharide groups on polysiloxane polymers. In the first part of this thesis, a new, smooth, efficient and fast method has been developed for the preparation of linear or hyperbranched polysiloxanes with lateral or terminal sugar groups. The preparation is done without the use of protecting groups for sugars. It avoids the use of acid or alkaline conditions for the deprotection thus preventing the decomposition of the siloxane chains before and after grafting the sugars. The polymers were characterized by 1H, 13C, 29Si NMR, IR and Size Exclusion Chromatography. These "glycosilicones" with grafting rate and weights adjustable at will, were subsequently used to efficiently stabilize preformed gold nanoparticles in aqueous solution even at high ionic strengths. The reducing properties of amino sugars used in this thesis for the synthesis of glycosilicones were used for a direct synthesis of nanoparticles under milder conditions than in conventional synthesis methods (such as reducing the gold salt with sodium borohydride). These amino sugars (glucosamine, glucamine) play the role of both reducing agents and stabilizers in aqueous media. The advantage of this method lies in the use of a single nontoxic reagent which can be useful for using these nanoparticles in biological tests. The one pot synthesis occurs at room temperature and leads to the formation of spherical nanoparticles with a good yield, but also induces anisotropic growth leading to the production of star shaped or multi-branched nanoparticles with very high yields. The size and number of branches of nano-stars were modulated by adjusting the experimental conditions. They were characterized regarding to their morphology, stability and optical properties by electron microscopy and UV spectroscopy
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Ung, Diane. "Nanoparticules métalliques anisotropes synthétisées par vie chimique : fils, plaquettes et particules hybrides de cobalt-nickel, caractérisations physico-chimiques et propriétés magnétiques : fils d'argent auto-organisés." Paris 7, 2005. https://tel.archives-ouvertes.fr/tel-00202393.
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Ballot, Noémie. "Matériaux nanométriques à base de métaux 3d (Fe, Co, Ni) : Nouvelles voies de synthèse et caractérisations." Thesis, Paris 13, 2014. http://www.theses.fr/2014PA132065/document.
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L’intérêt grandissant envers les nanomatériaux a base des métaux de transition 3d comme le cobalt, le nickel et le fer trouve son origine dans les propriétés intrinsèques de ces éléments (forte aimantation du fer et constante magnétocristalline élevée du cobalt) combinées aux propriétés particulières offertes par la taille nanométrique et l’anisotropie de ces alliages. Parmi les nombreuses voies de synthèse dites de chimie douce, le procède polyol permet l’élaboration de plusieurs classes de matériaux inorganiques a l’état finement divises (oxydes, hydroxydes et métaux) grâce aux réactions de réduction et d’hydrolyse qui peuvent être conduites et contrôlées dans les milieux polyols. Le premier axe de ce travail a consisté à tirer profit de l’état finement divise des oxydes et hydroxydes élabores en milieu polyol pour l’obtention de métaux et alliages correspondants, au moyen d’une réduction ménagée a l’état solide sous flux d’hydrogène. Il a alors été possible d’aboutir a des particules de CoFe2, CoFe, NiFe, Ni3Fe et Fe ferromagnétiques avec une température de blocage supérieure a 300 K. Le deuxième axe de travail a trait a l’élaboration d’objets anisotropes. Pour ce faire, une nouvelle approche est proposée : la synthèse en milieu polyol assistée par l’application d’un champ magnétique. Ce type de synthèse mené a des nanofils d’akaganeite β-FeOOH et a des nanoparticules d’oxydes spinelles. Une réduction relativement douce (300 °C) des nanofils d’akaganeite permet de l’obtention de phases spinelles de même morphologie et avec des propriétés magnétiques en accord avec la composition chimique et le caractère nanométrique des particules (comportement superparamagnétique avec une température de blocage proche de 300 K, Ms élevée et Hc dépendant de la nature de l’élément M se trouvant dans le spinelle MFe2O4 : élevé dans le cas du cobalt et faible dans le cas du fer et du nickel)The growing interest in nanomaterials based on 3d transition metals such as cobalt, iron and nickel finds its origin in the intrinsic properties of these elements (high magnetization of iron and high magnetocristalline constant of cobalt) combined with particular property due to nanometric size and anisotropy of these alloys. Among the numerous synthetic routes, the polyol method which belongs to the chimie douce routes allows the elaboration of several finely divided inorganic materials (oxides, hydroxides, metals) by means of reduction or forced hydrolysis reactions conducted in polyol medium. The main first contribution of this work was to take advantage of these finely divided oxides and hydroxides elaborated in polyol medium to obtain metals and alloys, through a controlled reduction in solid form under hydrogen flow. Ferromagnetic particles of CoFe2, CoFe, NiFe, Ni3Fe and Fe with a blocking temperature above 300 K were obtained. The second main contribution of this work relates elaboration of anisotropic objects. Further, a new approach is proposed: forced hydrolysis in polyol medium assisted by applying a magnetic field. This type of synthesis leads to akaganeite β7&eOOH nanowires and spinel oxides nanoparticles. A relative mild reduction (300 °C) of akaganeite nanowires allows to obtain spinels phase with same morphology and magnetic properties in agreement with the chemical composition and the particles nanoscale (superparamagnetic behavior with blocking temperaturenear 300 K, high Ms and Hc dependent on the nature of the M element in the spinel MFe2O4, high in the case of cobalt and low for nickel and iron)
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Oyarzún, Medina Simón. "Spintronics in cluster-assembled nanostructures." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10166/document.
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Dans les dernières années, la miniaturisation progressive des dispositifs de stockage magnétique a rendu nécessaire de comprendre comment les propriétés physiques sont modifiées par rapport à l'état massif lorsque les dimensions sont réduites à l'échelle nanométrique. Pour cette raison, une méthode précise de préparation et caractérisation de nanostructures est extrêmement importante. Ce travail se concentre sur les propriétés magnétiques et de transport de nanoparticules de cobalt incorporées dans des matrices de cuivre. Notre dispositif expérimental nous permet de contrôler indépendamment la taille moyenne des agrégats, la concentration et la composition chimique. La production des agrégats de cobalt est basée sur la pulvérisation cathodique et l'agrégation dans la phase gazeuse. Cette source permet de produire des agrégats dans une large gamme de taille, de un à plusieurs milliers d'atomes. Dans un premier temps, nous avons étudié le rôle des interactions entre particules dans les propriétés de transport et magnétiques, en augmentant la concentration des nanoparticules de cobalt (à partir de 0.5 % à 2.5 % et 5 %). Nos résultats démontrent les précautions nécessaires et constituent une base solide pour de futures études sur les propriétés spintroniques des systèmes granulaires. Dans le but de décrire les propriétés magnétiques intrinsèques d'agrégats, nous avons préparé des échantillons fortement dilués (_0.5%) pour différents diamètres d'agrégats de 1.9 nm à 5.5 nm. Nous avons constaté que les propriétés magnétiques sont dépendantes de la taille. L'utilisation d'une caractérisation magnétique complète, sensible à la variation de l'anisotropie magnétique efficace, nous montre que l'anisotropie magnétique est dominée par les contributions de la surface ou de la forme des nanoparticulesIn the last years, the progressive miniaturization of magnetic storage devices has imposed the necessity to understand how the physical properties are modified with respect to the bulk when the dimensions are reduced at the nanometric scale. For this reason an accurate method of preparation and characterization of nanostructures is extremely important. This work focuses on the magnetic and transport properties of cluster-assembled nanostructures, namely cobalt nanoparticles embedded in copper matrices. Our setup allows us to independently control the mean cluster size, the concentration and the chemical composition. The cobalt cluster production is based on magnetron sputtering and gas phase aggregation. The performance of the source permits a wide range of cluster masses, from one to several thousand atoms. As a first step we studied the role of inter-particle interactions in the transport and magnetic properties, increasing the cobalt nanoparticle concentration (from 0.5% to 2.5% and 5%). Our results demonstrate the necessary precautions and constitute a solid basis for further studies of the spintronic properties of granular systems. Finally, in order to describe the intrinsic magnetic properties of cluster-assembled nanostructures, we prepared strongly diluted samples (_0.5%) for different cluster sizes from 1.9 nm to 5.5 nm. We found that the magnetic properties are size-dependent. Using a complete magnetic characterization, sensitive to the change in the effective magnetic anisotropy, we show that the magnetic anisotropy is dominated by the contributions of the surface or of the shape of the nanoparticles
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Han, Shuaiyuan. "Supramolecular Janus nanorods formed by self-assembly of polymers in aqueous medium." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS140.
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Contrôler la forme et la structure des nanoparticules est utile dans le cadre de nombreuses applications. L’objectif de cette étude était de déterminer si et comment la liaison hydrogène peut être utilisée pour contrôler la forme et la structure fine de nanoparticules de polymère formées dans l'eau par auto-assemblage. Les principaux effets démontrés sont les suivants. (1) Des particules cylindriques très stables d'une longueur de plusieurs centaines de nanomètres et d'un diamètre monodisperse de 10 nm peuvent être obtenues dans l'eau par auto-assemblage de polymères hydrophiles décorés par un motif penta-urée. Aucun domaine hydrophobe particulier n'est requis pour sa stabilité. (2) La structure de l'espaceur reliant le motif associatif au polymère a un effet précédemment sous-estimé sur la longueur des particules cylindriques. (3) Un motif associatif par liaisons hydrogène peut être associé à un polymère thermosensible, pour former des particules cylindriques à température ambiante mais qui se désassemblent à des températures plus basses. (4) Des particules cylindriques Janus (c'est-à-dire des particules non-centrosymétriques, allongées, avec deux faces de compositions différentes) peuvent être obtenuesControlling the shape and the structure of nanoparticles is useful in the context of many applications. The objective of this study was to determine if and how hydrogen bonded self-assembly in water can be used to control the shape and the fine structure of polymer nanoparticles. The main effects that were demonstrated are the following. (1) Very stable rod-like particles with a length of several hundreds of nanometers and a monodisperse diameter of 10 nm can be obtained in water by self-assembly of hydrophilic polymers decorated by a penta-urea sticker. No obvious hydrophobic domain is required for its stability. (2) The structure of the spacer connecting the sticker to the polymer has a previously underestimated effect on the length of the nanorods. (3) The control of the shape of the nanoparticles by a hydrogen bonded sticker can be combined with the thermo-responsiveness of the polymer, so that the nanorods formed at room temperature disassemble at lower temperatures. (4) It is possible to prepare Janus nanorods (i.e. non-centrosymmetric rod-like particles with two sides of different compositions) by using unsymmetrical and complementary tris-urea stickers in water. The Janus topology is obtained independently of the actual polymers used. The versatility and scalability of this approach allows to investigate the rich properties that can be predicted for such easily functionalizable nano-objects. In particular, we show these Janus nanorods are superior stabilizers for oil in water emulsions
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Chaudan, Elodie. "Développement de nanoémetteurs polarisés pour leur application comme sondes d'orientation." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX063/document.
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Les nanoparticules luminescentes sont particulièrement étudiées pour leur application dans les systèmes d’éclairages ou comme sondes en bio-imagerie. Parmi elles, les nanoparticules anisotropes de matrices cristallines dopées par des ions lanthanides présentent une émission polarisée, qui dépend de la symétrie des sites des ions émetteurs. Le lien entre direction de polarisation et axes cristallins des nanocristaux permet de déterminer leur orientation, et peut donc être exploité pour suivre l'orientation d’objets ou pour caractériser la déformation de milieux hôtes.Les objectifs de ce doctorat ont été de s’intéresser aux origines fondamentales de l’émission polarisée de nanobâtonnets de phosphate de lanthane dopés par des ions europium trivalents (LaPO4:Eu) et d’utiliser la luminescence polarisée à des mesures d’orientation.Dans une première partie, les nanobâtonnets de LaPO4:Eu ont été synthétisés puis alignés sous forme des films orientés. La luminescence de ces films a permis de suivre avec précision la transition de phase de la matrice hôte, de sa structure hexagonale à une structure monoclinique ; et de mettre en évidence la présence de défauts structuraux. La polarisation des spectres de luminescence a ensuite été étudiée. Les taux de polarisation mesurés sont plus élevés pour la phase monoclinique que pour la phase hexagonale. La sensibilité du spectre de polarisation au milieu diélectrique qui les entoure a été mise en évidence.La seconde partie de cette étude porte sur l’utilisation de la polarisation des nanobâtonnets de LaPO4:Eu pour déterminer leur orientation. La connaissance des spectres polarisés des films parfaitement alignés a permis de déterminer le paramètre d’ordre d’une suspension de nanobâtonnets désordonnés en écoulement dans un canal microfluidique puis d’estimer le taux de cisaillement de cet écoulement. Notre étude a permis de préciser quantitativement les conditions dans lesquelles l’utilisation de la luminescence polarisée comme sonde locale du taux de cisaillement d’un écoulement est valideLuminescent nanoparticles have been studied for their applications in lighting devices or as probes in biology. Among these nanoparticles, the anisotropic crystals doped with lanthanides ions emit linearly polarized light. The relation between the polarized directions and the crystallographic axis of the nanocrystals allow determining their 3D orientation, which could be an asset to track objects or to characterize flows.The purposes of this thesis were to investigate the origin of the polarized light of nanorods of lanthanum phosphate doped with europium ions (LaPO4:Eu) and to apply this polarized light to determine their orientation.First, nanorods of LaPO4:Eu are synthesized and aligned to prepare oriented films. The phase transition of the LaPO4 matrix is investigated, from the hexagonal to the monoclinic structure. The luminescence is used to track precisely the transition and show the presence of structural defects. Then the polarized spectra are observed. The polarization degrees of the monoclinic phase are higher than those of the hexagonal one. The sensitivity of the polarization with the dielectric medium is also shown.Then, the polarized light is used to determine the orientation of the nanorods. The knowledge of the polarized spectra along he nanorods axis and perpendicularly to it is used to calculate the order parameter of disoriented nanorods in a microfluidic channel and then to estimate the shear rate of the flow. Our study allows quantifying the conditions in which the nanorods can be used as probes to measure the local shear rate
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Tallet, Clémence. "Nanocomposites plasmoniques anisotropes à base de copolymères à blocs et de nanoparticules d’or." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14637/document.
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La nanochimie et l’auto-assemblage sont des voies prometteuses de fabrication de matériaux nanostructurés aux propriétés optiques innovantes dans le domaine visible. Dans cette étude, des nanocomposites plasmoniques anisotropes sont formulés en introduisant sélectivement des nanoparticules métalliques dans des phases ordonnées de copolymères diblocs symétriques selon différentes stratégies d’incorporation. Pour la stratégie de post-incorporation, des nanoparticules d’or présynthétisées en milieu aqueux sont introduites sélectivement dans des phases pré-ordonnées d’un copolymère dibloc amphiphile. L’incorporation directe consiste àmélanger des nanoparticules d’or présynthétisées et un copolymère dibloc dans un solvant commun.La synthèse in situ de nanoparticules consiste à réduire des précurseurs métalliques préalablement introduits dans un des deux blocs d’un copolymère via une étape de réduction. Nous étudions, en particulier, comment la taille des nanoparticules d’or et leur fraction volumique influencent la nanostructure et les propriétés optiques de ces films nanocomposites. La morphologie des films macroscopiques est étudiée par microscopie électronique à transmission et diffusion des rayons Xaux petits angles. Les films minces de nanocomposites sont caractérisés structurellement parmicroscopie à force atomique, microscopie électronique à transmission et réflectivité des rayons X. Les indices optiques déterminés par ellipsométrie spectroscopique peuvent être décrits par un modèle de Maxwell-Garnett, prenant éventuellement en compte de façon phénoménologique les effets de couplage entre nanoparticules d’orNanochemistry and self-assembly are promising ways to fabricate nanostructuredmaterials with innovative optical properties for visible light. In this work, anisotropic plasmonicnanocomposites are formulated by selectively introducing metallic nanoparticles in ordered phasesof symmetric dibloc copolymers with different strategies. For the strategy of post-incorporation, presynthesizedgold nanoparticles in aqueous medium are selectively introduced in pre-ordered phasesof an amphiphilic dibloc copolymer. Direct incorporation consists in mixing pre-synthesized goldnanoparticles and dibloc copolymer in a common solvent. In situ synthesis of nanoparticles consistsin reducing metallic precursors previously introduced in one of two blocks of a copolymer via areduction step. The influence of the size and the volume fraction of gold nanoparticles on thenanostructure and the optical properties of the nanocomposite films have been particularly studied.Morphology of macroscopic films is studied by transmission electron microscopy and small angle Xrayscattering. The nanocomposite thin films are structurally characterized by force atomicmicroscopy, transmission electron microscopy and X-ray reflectivity. The optical indices obtained byspectroscopic ellipsometry can be described with Maxwell-Garnett models, which can take intoaccount phenomenologically the effects of coupling between gold nanoparticles
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Daffé, Niéli. "Anisotropies and Magnetic Couplings of Texturable Ferrofluids." Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066640.pdf.
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Les ferrofluides sont des suspensions colloïdales de nanoparticules magnétiques dispersées dans un liquide porteur. La possibilité de moduler les propriétés des ferrofluides in situ en appliquant un champ magnétique externe leur procure un fort potentiel d’étude, à la fois d’un point de vue fondamental ou pour des applications industrielles variées. En particulier, les nanospinels de ferrite ferrimagnétiques MFe2O4 (M = Fe2+, Co2+, Mn2+…) sont largement étudiés pour leurs propriétés électriques et magnétiques. Plus spécifiquement, une forte énergie d’anisotropie de ces matériaux à l’échelle nanométrique est requise pour des applications dans le stockage de l’information ou l’hyperthermie pour lesquels ils sont considérés. Une connaissance fine des mécanismes régissant ces propriétés d’anisotropies magnétiques est ainsi primordiale pour la création de nouveaux objets aux propriétés magnétiques contrôlées à l’échelle nanométrique. L’originalité de notre approche consiste à utiliser une technique fine du magnétisme, le dichroïsme magnétique circulaire des rayons X (XMCD) à l’étude des anisotropies et couplages magnétiques des nanospinels composants les ferrofluides. Au cours de cette thèse, nous nous sommes intéressés à différentes stratégies possibles pour induire une forte énergie d’anisotropie aux nanospinels de ferrite par l’utilisation de cobalt. Des nanoparticules de tailles et compositions variées ont été obtenues par différentes voies de synthèse, et nous démontrons que l’anisotropie magnétique de ces systèmes est fortement gouvernée par la symétrie de site du Co2+ en structure spinel qui peut être directement corrélé au processus de synthèse utilisé. Nous nous sommes aussi intéressés à l’ordre et au couplage magnétique de ferrite spinels structurés en coeur-coquille, dont le cœur et la coquille sont réalisés à partir de matériaux aux propriétés magnétiques intrinsèques différentes. Nous montrons ainsi que pour des nanospinels MnFe2O4@CoFe2O4, la très fine coquille formée de CoFe2O4 impose une forte anisotropie magnétique au cœur doux de MnFe2O4. Enfin, nous nous sommes intéressés à une troisième classe de ferrofluide à base de nanospinels, les ferrofluides binaires, constitué d’un mélange physique de ferrofluides aux propriétés magnétiques intrinsèques différentes. Pour de tels systèmes, il est essentiel de préserver le liquide porteur du ferrofluide pour ne pas dénaturer les interactions entre particules existantes. L’un des objectifs de cette thèse fut donc d’étendre la technique du XMCD à l’étude d’échantillons de ferrofluides in situ, dans leur phase liquide ou gelée. Nous avons débuté la conception d’une cellule liquide compatible avec les rayons X mous et un environnement ultra-vide sur la ligne de lumière DEIMOS (SOLEIL) qui est toujours en développementFerrofluids are colloidal suspensions of magnetic nanoparticles dispersed in a carrier liquid. The intimate interaction between the magnetic nanoparticles and the liquid provides a unique system, from both fundamental and industrial application point of views, whose flow and properties can be precisely controlled using an external magnetic field. Magnetic nanoparticles of spinel ferrites MFe2O4 (M = Fe2+, Co2+, Mn2+…) are of particular scientific interest and have been extensively studied for their electrical and magnetic properties. Spinel ferrites find potential applications, notably in storage devices, for computers, or hyperthermia, for cancer treatment, where high magnetic anisotropy energies are required at the nanoscale. However, deeper knowledges of the fine mechanisms playing a significant role on the magnetic anisotropies existing in the nanospinels are necessary to help the creation of rationalized materials with controlled magnetic anisotropies for the requirement of the system. In this thesis, we have used X-ray Magnetic Circular Dichroism (XMCD) as an original approach for probing the magnetic anisotropies and magnetic couplings of nanospinels obtained in ferrofluids. The nanoparticles are iron bearing spinels for which cobalt ions have been introduced in the spinel structure of the nanoparticles as a true makers of magnetic anisotropy. First, magnetic nanospinels have been synthesized by tuning their size and composition and using different synthesis processes. XMCD investigations revealed that the coercive field of the nanospinels is governed by the concentration of Co2+ ions sitting in octahedral sites of the spinel structure, and this can be directly linked to some synthesis parameters. Then, we have investigated core@shell nanoparticles, which can be synthesized with an appropriate choice of magnetic anisotropies for the core and the shell in order to tailor optimal magnetic properties. In the case of MnFe2O4@CoFe2O4, our findings reveal that the very thin CoFe2O4 shell imposes a strong magnetic anisotropy to the otherwise very soft MnFe2O4 core. The other class of ferrofluids that has been investigated during this thesis are binary ferrofluids that are constituted of two different types of magnetic nanoparticles. For such systems, the carrier liquid must be preserved to understand the magnetic interactions in the ferrofluid as they are. Another motivation of this thesis was thus to extend XMCD to the in situ investigation of the nanospinels dispersed in ferrofluids. We have been started a liquid cell development in the DEIMOS beamline at SOLEIL. The setup is still in progress and is aimed at being compatible with soft X-Rays short penetration depth and ultra-high vacuum environment. Hard X-ray photon-in/photon-out spectroscopy coupled to XMCD (1s2p RIXS-MCD) can be a very valuable alternative to soft X-ray XMCD at K-edge of 3d elements when liquid cell sample environment is required. The instrumental development of a liquid cell used with 1s2p RIXS-MCD spectroscopy allowed us to investigate the nanoparticles directly in the ferrofluids revealing interparticles magnetic couplings in binary ferrofluids
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Robert, Anthony. "Étude du couplage magnétique dans des nanoparticules bimétalliques de FeRh et de CoTb." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1309/document.
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L'enregistrement magnétique sur disque dur est aujourd'hui le moyen le plus fiable pour stocker l'information. L'enregistrement perpendiculaire magnétique a permis de multiplier par dix la densité de stockage par rapport à l'enregistrement longitudinal. Mais cette diminution de la taille des bits d'information se heurte à une limite physique, dite « limite superparamagnétique », qui correspond à une instabilité thermique de l'aimantation. Afin de repousser cette limite, il convient donc de fabriquer des bits avec une forte anisotropie. Mais plus les grains ont une grande anisotropie magnétique plus le champ nécessaire pour l'écriture doit être important. L'intérêt d'avoir un matériau aux propriétés magnétiques ajustables prend ainsi tout son sens. En utilisant des matériaux aux énergies d'anisotropies facilement modifiables, il n'est donc pas nécessaire de faire évoluer les têtes d'écriture. C'est dans cette optique que nous avons choisi d'étudier deux systèmes bimétalliques. Le premier est un alliage entre un métal de transition (Co) et une terre-rare lourde (Tb). Le deuxième système combine un métal de transition (Fe) et un métal magnétiquement polarisable (Rh). Dans ce travail, nous présenterons les résultats obtenus sur des nanoparticules de Co80Tb20 et de Fe50Rh50 de moins de 10 nm de diamètre, préparées par MS-LECBD (« Mass Selected Low Energy Cluster Beam Deposition »). Les échantillons, sous forme de multicouches, sont obtenus par dépôts séquentiels d'agrégats et de _lm de carbone. Dans un premier temps, une caractérisation structurale (dispersion de taille, morphologie, composition, structure cristallographique) par microscopie électronique a été réalisé pour les deux systèmes. Dans un second temps, nous avons étudié les propriétés magnétiques de ces agrégats par magnétométrie SQUID et dichroïsme magnétique circulaire (x-ray magnetic circular dichroism (XMCD)). Nous verrons, dans le cas du CoTb, que la réduction de taille entraine de profonds changements de ses propriétés par rapport au massif, notamment au niveau du couplage entre les sous-réseaux magnétiques de Co et de Tb. Dans le cas du FeRh, après avoir montré qu'un traitement thermique permet d'obtenir des agrégats chimiquement ordonnées B2, nous verrons l'influence des effets de taille sur la transition métamagnétique caractérisant cet alliageThe magnetic data storage is the most reliable way to store information. The perpendicular recording multiplied the storage density by ten with respect to the longitudinal recording. However, this reduction in the size of the information bits comes up against a physical limit, called the "superparamagnetic limit", which corresponds to a thermal instability of the magnetization. In order to push back this limit, it is therefore necessary to manufacture bits with strong anisotropy. But the more the grains have a large magnetic anisotropy the greater the field needed for writing must be. Thus, it's a great advantage of having a material with adjustable magnetic properties. By using materials with easily modifiable anisotropy energies, it is therefore not necessary to change the writing heads. It is with this in mind that we have chosen to study two bimetallic systems. The first is an alloy between a transition metal (Co) and a heavy earth-rare (Tb). The second system combines a transition metal (Fe) and a magnetically polarizable metal (Rh). In this work, we present results obtained on nanoparticles of Co80Tb20 and Fe50Rh50 of less than 10 nm in diameter, prepared by MS LECBD ("Mass Selected Low Energy Cluster Beam Deposition"). The samples, in the form of multilayers, are obtained by sequential deposition of nanoparticles and carbon _lm. First, a structural characterization (size dispersion, morphology, composition, crystallographic structure) by electron microscopy was carried out for both systems. Secondly, we have studied the magnetic properties of these nanoparticles by SQUID magnetometry and magnetic circular dichroism (XMCD). We will see, in the case of CoTb that the reduction in size leads to profound changes in its properties with respect to the massif, especially in the coupling between the magnetic sub-lattices of Co and Tb. In the case of FeRh, after having shown that a heat treatment makes it possible to obtain chemically ordered nanoparticles B2, we will see the influence of the size effects on the metamagnetic transition characterizing this alloy
Books on the topic "Nanoparticule anisotrope"
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Chemistry, Royal Society of. Nanoparticles with Morphological and Functional Anisotropy: Faraday Discussion 191. Royal Society of Chemistry, The, 2016.
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Mørup, Steen, Cathrine Frandsen, and Mikkel F. Hansen. Magnetic properties of nanoparticles. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.20.
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This article discusses the magnetic properties of nanoparticles. It first considers magnetic domains and the critical size for single-domain behavior of magnetic nanoparticles before providing an overview of magnetic anisotropy in nanoparticles. It then examines magnetic dynamics in nanoparticles, with particular emphasis on superparamagnetic relaxation and the use of Mössbauer spectroscopy, dc magnetization measurements, and ac susceptibility measurements for studies of superparamagnetic relaxation. It also describes magnetic dynamics below the blocking temperature, magnetic interactions between nanoparticles, and fluctuations of the magnetization directions. Finally, it analyzes the magnetic structure of nanoparticles, focusing on magnetic phase transitions and surface effects, non-collinear spin structures, and magnetic moments of antiferromagnetic nanoparticles.
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(Editor), L. Andrew Lyon, Stephan J. Stranick (Editor), and Christine Dolan Keating (Editor), eds. Anisotropic Nanoparticles--Synthesis, Characterization and Applications: Symposium Held November 27-29, 2000, Boston, Massachusetts, U.S.A. (Materials Research Society Symposia Proceedings, V. 635.). Materials Research Society, 2001.
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Metallic Nanomaterials. Wiley-VCH Verlag GmbH, 2009.
Find full textBook chapters on the topic "Nanoparticule anisotrope"
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Bisoyi, Hari Krishna, and Quan Li. "Liquid Crystalline Anisotropic Nanoparticles: From Metallic and Semiconducting Nanoparticles to Carbon Nanomaterials." In Anisotropic Nanomaterials, 209–40. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18293-3_6.
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Mai, Nguyen T., Derrick Mott, and Shinya Maenosono. "Anisotropic Nanoparticles for Efficient Thermoelectric Devices." In Complex-Shaped Metal Nanoparticles, 521–43. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527652570.ch16.
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Xue, Chenming, and Quan Li. "Anisotropic Gold Nanoparticles: Preparation, Properties, and Applications." In Anisotropic Nanomaterials, 69–118. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18293-3_3.
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Rocha, Tulio C. R., Herbert Winnischofer, and Daniela Zanchet. "Structural Aspects of Anisotropic Metal Nanoparticle Growth: Experiment and Theory." In Complex-Shaped Metal Nanoparticles, 215–38. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527652570.ch6.
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Aherne, Damian, Deirdre M. Ledwith, and John M. Kelly. "Synthesis of Anisotropic Noble Metal Nanoparticles." In Metal-Enhanced Fluorescence, 295–362. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470642795.ch11.
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Stone, John W., Alaaldin M. Alkilany, Majd A. Hamaly, and Stephanie Canonico-May. "Biomedical Applications of Anisotropic Gold Nanoparticles." In Nanostructure Science and Technology, 399–426. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-59662-4_13.
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Eichhorn, S. Holger, and Jonathan K. Yu. "Directed Assembly and Self-organization of Metal Nanoparticles in Two and Three Dimensions." In Anisotropic Nanomaterials, 289–336. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18293-3_8.
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Pastoriza-Santos, Isabel, Yasushi Hamanaka, Kazuhiro Fukuta, Arao Nakamura, and Luis M. Liz-MarzáN. "Anisotropic Silver Nanoparticles: Synthesis and Optical Properties." In Low-Dimensional Systems: Theory, Preparation, and Some Applications, 65–75. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0143-4_6.
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Ferchmin, A. R., H. Puszkarski, and M. Krawczyk. "On the Effect of Unidirectional Anisotropy in Ferromagnetic Nanoparticles." In Molecular Low Dimensional and Nanostructured Materials for Advanced Applications, 293–96. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0349-0_34.
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Davidson, Patrick, and Jean-Christophe P. Gabriel. "Self-Assemblies of Anisotropic Nanoparticles: Mineral Liquid Crystals." In Nanocrystals Forming Mesoscopic Structures, 173–212. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527607587.ch7.
Full textConference papers on the topic "Nanoparticule anisotrope"
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Jambhulkar, Sayli, and Kenan Song. "1D and 2D Nanoparticle Assembly Compliant With Tuned 3D-Printed Topology." In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-85050.
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Abstract Nanoparticle-included polymeric composite coatings with preferential nanoparticle alignment and oriented structures show improved functional and structural properties than randomly oriented structures, suitable for broad applications in microelectronics, automobile, defense, and space missions. Traditionally used techniques, such as drop-casting, chemically modified surfaces, and external fields, have been used for self-assembly but with several disadvantages, such as material limitations. Thus, there is a need to develop a new approach for generating hierarchical nanoparticle structures. Our unique processing is based on advanced additive manufacturing with a colloidal suspension-based deposition approach for layer-by-layer deposition of anisotropic nanoparticles. Leveraging the colloidal deposition technique, these anisotropic nanoparticles were deposited onto the 3D printed substrates with designed patterning. The presence of micropatterns generates selective nanoparticle distribution and assembly along with hydrodynamic forces to initiate the region-specific microscale patterning and nanoscale alignment of 1D and 2D nanoparticles. The polymer and nanoparticle composite film showed different deposition morphologies (e.g., straight or wavy films). In addition, the influence of nanoparticle deposition morphology on functional properties was investigated. This novel technique shows the potential to scale up microelectronics production by 3D printing electronic structures, including interdigitated devices, supercapacitors, fuel cells, and circuits.
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Hopkins, Patrick E., Manish Mittal, Leslie M. Phinney, Anne M. Grillet, and Eric M. Furst. "Tunable Thermal Conductivity of TiO2 Films of Close-Packed Nanoparticles." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44136.
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We report on the ultra-low thermal conductivity of a series of convectively assembled, anisotropic titania (TiO2) nanoparticle films. The TiO2 films are fabricated on aluminum coated glass substrates by flow coating a suspension of ellipsoidal colloidal nanoparticles, resulting in structured films with tailored order. Time domain thermoreflectance is used to measure the thermal conductivity of the TiO2 films. The thermal conductivities of these nanoparticle films are dependent on nanoparticle orientational order and films with more randomly oriented particles exhibit thermal conductivities less than the amorphous limit.
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Kroychuk, M. K., E. V. Melik-Gaykazyan, A. S. Shorokhov, D. Y. Choi, V. V. Zubyuk, T. V. Dolgova, M. R. Shcherbakov, D. N. Neshev, A. A. Fedyanin, and Y. S. Kivshar. "Nonlinear anisotropy in silicon nanoparticle oligomers." In ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING: FROM THEORY TO APPLICATIONS: Proceedings of the International Conference on Electrical and Electronic Engineering (IC3E 2017). Author(s), 2017. http://dx.doi.org/10.1063/1.4998096.
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Allia, P., G. Barrera, P. Tiberto, T. Nardi, Y. Leterrier, and M. Sangermano. "Fe3O4 nanoparticles and nanocomposites for applications in biomedicine and the ICTs: Nanoparticle aggregation, interaction and effective magnetic anisotropy." In 2015 IEEE International Magnetics Conference (INTERMAG). IEEE, 2015. http://dx.doi.org/10.1109/intmag.2015.7157444.
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Liu, Wei. "Ultradirectional scattering of radially anisotropic nanoparticles." In 2016 Progress in Electromagnetic Research Symposium (PIERS). IEEE, 2016. http://dx.doi.org/10.1109/piers.2016.7734212.
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Kaur, Navneet, and S. D. Tiwari. "Estimation of magnetic anisotropy constant of magnetic nanoparticles." In DAE SOLID STATE PHYSICS SYMPOSIUM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0017219.
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Kahraman, A., C. Bacellar, M. Nazari, A. Cannizzo, and C. Milne. "Probing the Ultrafast Charge Carrier Dynamics in Mn-doped ZnO Nanoparticles." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.w4a.4.
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Manganese doping of ZnO nanoparticles, by introducing midgap states, is a potential solution to overcome the limitations of rapid recombination of photogenerated carriers. Ultrafast transient anisotropy measurements uncover the trapping dynamics upon Mn doping.
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Vial, Karine, and Dhananjay Kumar. "Shape Anisotropy Study of Nickel and Iron/Cobalt Nanoparticles." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12631.
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Shape anisotropy of Nickel and Iron/Cobalt nanoparticles embedded respectively in gold and Titanium/Nitride thin film matrix on a sapphire substrate has been study. The samples have been fabricated using a pulsed laser deposition. The measurements of magnetic moment per cm2 versus magnetic field at different temperatures (10 K and from 50 K to 300 K every 50 K) and with a magnetic field applied parallel to the sample or perpendicularly have been made in order to determine the coercivity of the material for these parameters. We also report our investigation on the magnetoresistance effect per cm2, where measurements have been lead for different temperatures (10 K, 100 K, 200 K, and 300 K) and two positions of the sample (parallel and perpendicular to the magnetic field). The comparison of the two cases, magnetic field parallel and magnetic field perpendicular to the sample, has shown that the difference of coercivity between them decreases when the temperature increases for all samples. For gold/nickel monolayer samples the difference varies from 120 Oe at 10 K to 6 Oe at 300 K for coercivities of about 200 Oe to 450 Oe at 10 K depending on the sample to coercivities of about 80 Oe to 150 Oe at 300K depending on the sample. For Titanium-Nitride/ Iron-Cobalt monolayer and trilayers samples the difference of coercivities varies between 10 Oe to 500 Oe depending on the temperature and the sample for coercivities between 30 Oe and 750 Oe. The difference in the percentage of magnetoresistance at 0 Oe is between 5 to 40% for Au/Ni sample and 0% to 10% for TiN/FeCo samples.
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Ozaki, Ryotaro, Nagao Yoshiki, Kazunori Kadowaki, Yutaka Kuwahara, and Seiji Kurihara. "Optical properties of self-assembled anisotropic gold nanoparticles." In 2014 International Symposium on Electrical Insulating Materials (ISEIM). IEEE, 2014. http://dx.doi.org/10.1109/iseim.2014.6870762.
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Kempa, Thomas J. "Symmetry broken nanostructures: Anisotropic and multi-component nanoparticles." In Asia Communications and Photonics Conference. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/acpc.2017.s3h.1.
Full textReports on the topic "Nanoparticule anisotrope"
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Smalyukh, Ivan I. Nanostructured Colloidal Self-Assembly and Controlled Alignment of Anisotropic Nanoparticles. Office of Scientific and Technical Information (OSTI), September 2018. http://dx.doi.org/10.2172/1471983.
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