/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). These cubes were single crystals and were characterized by a slightly truncated shape bounded by {100}, {110}, and {111} facets. The presence of PVP and its molar ratio (in terms of repeating unit) relative to silver nitrate both played important roles in determining the geometric shape and size of the product. The silver cubes could serve as sacrificial templates to generate single-crystalline nanoboxes of gold: hollow polyhedra bounded by six {100} and eight {111} facets. Controlling the size, shape, and structure of metal nanoparticles is technologically important because of the strong correlation between these parameters and optical, electrical, and catalytic properties.

http://science.sciencemag.org/content/sci/298/5601/2176.full.pdf

Shape-Controlled Synthesis of Gold and Silver Nanoparticles

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Synthesis of monodisperse iron-platinum (FePt) nanoparticles by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine stabilizers is reported. The FePt particle composition is readily controlled, and the size is tunable from 3- to 10-nanometer diameter with a standard deviation of less than 5%. These nanoparticles self-assemble into three-dimensional superlattices. Thermal annealing converts the internal particle structure from a chemically disordered face-centered cubic phase to the chemically ordered face-centered tetragonal phase and transforms the nanoparticle superlattices into ferromagnetic nanocrystal assemblies. These assemblies are chemically and mechanically robust and can support high-density magnetization reversal transitions.

/pdf/monodisperse-fept-nanoparticles-and-ferromagnetic-fept-12j5xql32h.pdf

Monodisperse FePt Nanoparticles and Ferromagnetic FePt Nanocrystal Superlattices

The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946

http://depa.fquim.unam.mx/amyd//archivero/FidelmarLechugaSanabria_4940.pdf

Recent advances in the liquid-phase syntheses of inorganic nanoparticles.

Homogeneous and heterogeneous nucleations in the polyol process for the preparation of micron and submicron size metal particles

One of the newer tendencies in materials science has been to tailor-make classical products (long associated with old applications) with controlled properties for special uses, especially in high technology. Preparing dispersed systems in which all particles have nearly uniform size (monodisperse solids) is a typical example. This goal can be achieved in some cases through cleverly controlled particle growth from a liquid medium. Examples of such preparations include gold colloids prepared by Zsigmondy and later by Turkevich et al., sulfur sols obtained by LaMer, metal oxides and hydrous oxides prepared by Matijevic et al., silica, etc. These dispersions have been used either to check theories of colloid science, or to a lesser extent, for industrial purposes. In the case of fine metal particles, a uniform size distribution associated with a low degree of agglomeration, and sometimes the spherical shape, appear as particularly convenient characteristics for certain applications. The production of conductive inks or pastes for electronic materials and for the preparation of conductive paints are particularly good examples.In so-called thick film technology, conductive inks and pastes are screen printed on a ceramic substrate in order to form, after firing, a conductive film with a thickness less than 10 μm. This technique is, for instance, used to form the network in hybrid integrated circuits or the internal electrodes of multilayer ceramic capacitors.Metallic powders in thick film compositions are usually precious metals (Au, Ag, Pt, Pd), their mixtures, or alloys. Cheaper metals such as copper or nickel are tested and may be potential substitutes for precious metals in different specific applications. Powders for thick film composition are mainly obtained through chemical precipitation from aqueous or organic solutions, which yield high purity powders. Modification of precipitation parameters (such as the nature and the concentration of the starting metallic compound and of the reducing agent, reaction temperature, viscosity of the medium) and the addition of additives and surfactants, can often be used to control particle size and agglomeration.Over the past few years, we have developed a new process for preparing finely divided metal powders of easily reducible metals (such as precious metals and copper) or less reducible metals (such as cobalt, nickel, cadmium, or lead) by precipitation in liquid polyols. This reaction will be used as an example in order to discuss the mechanism of formation of uniform micrometer and submicrometer size metal particles by precipitation reactions.

Preparing Monodisperse Metal Powders in Micrometer and Submicrometer Sizes by the Polyol Process

Les caracteristiques generales et le mode de preparation des poudres metalliques intervenant dans la composition des encres et pâtes conductrices utilisees pour les applications electroniques sont exposes. Un procede original de preparation de poudres metalliques par reduction en milieu polyol est decrit. On montre comment on peut obtenir les caracteristiques morphologiques requises par la technologie des films epais : particules peu agglomerees de taille micronique homogene et controlee.

Poudres métalliques et technologie des films épais pour les applications électroniques

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Préparation de particules monodispersées de cobalt et de nickel de taille micronique et submicronique F. Fievet, F. Fievet-Vincent, J.-P. Lagier, B. Beaudoin, M. Figlarz

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J.P. Lagier

Papers

Homogeneous and heterogeneous nucleations in the polyol process for the preparation of micron and submicron size metal particles

Preparing Monodisperse Metal Powders in Micrometer and Submicrometer Sizes by the Polyol Process

Poudres métalliques et technologie des films épais pour les applications électroniques

Préparation de particules monodispersées de cobalt et de nickel de taille micronique et submicronique