Download or read book Surface controlled Mechanical Properties of Bulk Nanoporous Gold written by Nadiia Mameka and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study highlights a smart hybrid material based on nanoporous gold in an aqueous electrolyte whose stiffness and strength are reversibly tuned by external stimuli. The tunability of these effective mechanical properties is realized via application of electric potentials to the large gold-electrolyte interface of the material, and consequent control of the surface state through electrical polarization and adsorption. The experiments are implemented in situ under environmental control in a dynamic mechanical analyzer and a mechanical testing device. The results of the in situ experiments provide conclusive evidence for the impact of surface excess elasticity on the effective elastic response of nanostructures and support a hypothesis that surface tension is a dominant factor in controlling their plasticity.
Download or read book Nanoporous Gold written by Arne Wittstock and published by Royal Society of Chemistry. This book was released on 2012-03-28 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-surface-area materials have recently attracted significant interest due to potential applications in various fields such as electrochemistry and catalysis, gas-phase catalysis, optics, sensors and actuators, energy harvesting and storage. In contrast to classical materials the properties of high-surface-area materials are no longer determined by their bulk, but by their nanoscale architecture. Nanoporous gold (np-Au) represents the fascinating class of mesoporous metals that have been intensively investigated in recent years. The current interest and the increasing number of scientific publications show that np-Au by itself is an outstanding nano-material that justifies a book devoted to all aspects of its properties and applications. The resulting publication is a discussion of this unique nano-material and is an accessible and comprehensive introduction to the field. The book provides a broad, multi-disciplinary platform to learn more about the properties of nanoporous gold from an inter-disciplinary perspective. It starts with an introduction and overview of state-of-the-art applications and techniques characterizing this material and its applications. It then covers the progress in research within the last years. The chapters are in-depth overviews written by the world's leading scientists in the particular field. Each chapter covers one technique or application so that the reader can easily target their favoured topic and will get the latest and state-of-the-art information in the field.
Download or read book Deformation Behavior of Nanoporous Metals written by and published by . This book was released on 2007 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous open-cell foams are a rapidly growing class of high-porosity materials (porosity ≥ 70%). The research in this field is driven by the desire to create functional materials with unique physical, chemical and mechanical properties where the material properties emerge from both morphology and the material itself. An example is the development of nanoporous metallic materials for photonic and plasmonic applications which has recently attracted much interest. The general strategy is to take advantage of various size effects to introduce novel properties. These size effects arise from confinement of the material by pores and ligaments, and can range from electromagnetic resonances to length scale effects in plasticity. In this chapter we will focus on the mechanical properties of low density nanoporous metals and how these properties are affected by length scale effects and bonding characteristics. A thorough understanding of the mechanical behavior will open the door to further improve and fine-tune the mechanical properties of these sometimes very delicate materials, and thus will be crucial for integrating nanoporous metals into products. Cellular solids with pore sizes above 1 micron have been the subject of intense research for many years, and various scaling relations describing the mechanical properties have been developed.[4] In general, it has been found that the most important parameter in controlling their mechanical properties is the relative density, that is, the density of the foam divided by that of solid from which the foam is made. Other factors include the mechanical properties of the solid material and the foam morphology such as ligament shape and connectivity. The characteristic internal length scale of the structure as determined by pores and ligaments, on the other hand, usually has only little effect on the mechanical properties. This changes at the submicron length scale where the surface-to-volume ratio becomes large and the effect of free surfaces can no longer be neglected. As the material becomes more and more constraint by the presence of free surfaces, length scale effects on plasticity become more and more important and bulk properties can no longer be used to describe the material properties. Even the elastic properties may be affected as the reduced coordination of surface atoms and the concomitant redistribution of electrons may soften or stiffen the material. If, and to what extend, such length scale effects control the mechanical behavior of nanoporous materials depends strongly on the material and the characteristic length scale associated with its plastic deformation. For example, ductile materials such as metals which deform via dislocation-mediated processes can be expected to exhibit pronounced length scale effects in the sub-micron regime where free surfaces start to constrain efficient dislocation multiplication. In this chapter we will limit our discussion to our own area of expertise which is the mechanical behavior of nanoporous open-cell gold foams as a typical example of nanoporous metal foams. Throughout this chapter we will review our current understanding of the mechanical properties of nanoporous open-cell foams including both experimental and theoretical studies.
Download or read book Nanoporous Gold written by Arne Wittstock and published by Royal Society of Chemistry. This book was released on 2012 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a broad, multidisciplinary platform to learn more about the properties of nanoporous gold from an interdisciplinary perspective from an overview of state-of-the-art applications and techniques to the latest research progress.
Download or read book Micro and Nano Mechanical Testing of Materials and Devices written by Fuqian Yang and published by Springer Science & Business Media. This book was released on 2009-02-28 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale and nanostructured materials have exhibited different physical properties from the corresponding macroscopic coarse-grained materials due to the size confinement. As a result, there is a need for new techniques to probe the mechanical behavior of advanced materials on the small scales. Micro and Nano Mechanical Testing of Materials and Devices presents the latest advances in the techniques of mechanical testing on the micro- and nanoscales, which are necessary for characterizing the mechanical properties of low-dimensional materials and structures. Written by a group of internationally recognized authors, this book covers topics such as: Techniques for micro- and nano- mechanical characterization; Size effects in the indentation plasticity; Characterization of low-dimensional structure including nanobelts and nanotubes; Characterization of smart materials, including piezoelectric materials and shape memory alloys; Analysis and modeling of the deformation of carbon-nanotubes. Micro and Nano Mechanical Testing of Materials and Devices is a valuable resource for engineers and researchers working in the area of mechanical characterization of advanced materials.
Download or read book Noble and Precious Metals written by Mohindar Seehra and published by BoD – Books on Demand. This book was released on 2018-07-04 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of copper, silver, gold and platinum in jewelry as a measure of wealth is well known. This book contains 19 chapters written by international authors on other uses and applications of noble and precious metals (copper, silver, gold, platinum, palladium, iridium, osmium, rhodium, ruthenium, and rhenium). The topics covered include surface-enhanced Raman scattering, quantum dots, synthesis and properties of nanostructures, and its applications in the diverse fields such as high-tech engineering, nanotechnology, catalysis, and biomedical applications. The basis for these applications is their high-free electron concentrations combined with high-temperature stability and corrosion resistance and methods developed for synthesizing nanostructures. Recent developments in all these areas with up-to-date references are emphasized.
Download or read book Nanoscience written by Hans-Eckhardt Schaefer and published by Springer Science & Business Media. This book was released on 2010-08-26 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscience stands out for its interdisciplinarity. Barriers between disciplines disappear and the fields tend to converge at the very smallest scale, where basic principles and tools are universal. Novel properties are inherent to nanosized systems due to quantum effects and a reduction in dimensionality: nanoscience is likely to continue to revolutionize many areas of human activity, such as materials science, nanoelectronics, information processing, biotechnology and medicine. This textbook spans all fields of nanoscience, covering its basics and broad applications. After an introduction to the physical and chemical principles of nanoscience, coverage moves on to the adjacent fields of microscopy, nanoanalysis, synthesis, nanocrystals, nanowires, nanolayers, carbon nanostructures, bulk nanomaterials, nanomechanics, nanophotonics, nanofluidics, nanomagnetism, nanotechnology for computers, nanochemistry, nanobiology, and nanomedicine. Consequently, this broad yet unified coverage addresses research in academia and industry across the natural scientists. Didactically structured and replete with hundreds of illustrations, the textbook is aimed primarily at graduate and advanced-undergraduate students of natural sciences and medicine, and their lecturers.
Download or read book A Course on Damage Mechanics written by Jean Lemaitre and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new branch of science usually develops thus. Somebody publishes the basic ideas. Hesitatingly at first, then little by little, other original contributions appear, until a certain threshold is reached. Then, overview articles are printed, conferences are held, and a first mention is made in textbooks, until specialized monographs are written. Continuum darnage mechanics has reached that status now. To analyze or, if possible, to predict the failure of machine parts or other structures is one of the main goals of engineering science. Consequently fracture mechanics became one of its leading branches. It was based on the analysis of existing cracks. However, especially under conditions of cyclic loading, this might be too late to prevent a disaster. Therefore, the question regarding the precursory state, that is, the evolution of intemal darnage before macrocracks become visible, was then posed. One of the successful approaches to the problern was Weibull's theory which examined, in a statistical manner, the "weakest link" in the material volume under consideration. Unfortunately it proved too difficult mathematically to be applied to complicated parts or structures. Therefore it was highly appreciated by the scientific of material community when L. M. Kachanov published in 1958 a simple model darnage which subsequently could be extended to brittle elastic, plastic or viscous materials under all conditions of uniaxial or multiaxial, simple or cyclic loadings, so that it may be considered nearly universal.
Download or read book Nanoporous Gold As a Fuel Cell Material written by SHRUTI BAHARANI and published by LAP Lambert Academic Publishing. This book was released on 2011-03 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical dealloying has proven to be an efficient way of fabricating nanoporous gold, the morphology of which can be tailored by controlling factors such as the etching time, temperature of electrolyte, composition of the alloy, pre and /or post heat treatment and voltage to suit applications such as fuel cell electrodes and sensors. This work aims at studying the effect of such factors as the electrolyte concentration on the morphology of the emerging material. A model relating the processing parameters and pore size is established by statistical approaches using the Design Expert 7.1 software. An equation that captures the individual as well as interaction effects on nanoporous gold is proposed. The validity of the equation is verified by existing research results. Simulation of this material under applied external load was done to achieve static properties in comparison with bulk gold. The applications where this might be helpful have been mentioned.
Download or read book Nanoporous Materials Chemistry and Applications written by Mark Donald Allendorf and published by The Electrochemical Society. This book was released on 2007-09 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The papers included in this issue of ECS Transactions were originally presented in the symposium ¿Nanoporous Materials: Chemistry and Applications¿, held during the 211th meeting of The Electrochemical Society, in Chicago, Illinois, from May 6 to 11, 2007.
Download or read book Springer Handbook of Nanomaterials written by Robert Vajtai and published by Springer Science & Business Media. This book was released on 2013-08-20 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Springer Handbook of Nanomaterials covers the description of materials which have dimension on the "nanoscale". The description of the nanomaterials in this Handbook follows the thorough but concise explanation of the synergy of structure, properties, processing and applications of the given material. The Handbook mainly describes materials in their solid phase; exceptions might be e.g. small sized liquid aerosols or gas bubbles in liquids. The materials are organized by their dimensionality. Zero dimensional structures collect clusters, nanoparticles and quantum dots, one dimensional are nanowires and nanotubes, while two dimensional are represented by thin films and surfaces. The chapters in these larger topics are written on a specific materials and dimensionality combination, e.g. ceramic nanowires. Chapters are authored by well-established and well-known scientists of the particular field. They have measurable part of publications and an important role in establishing new knowledge of the particular field.
Download or read book Statistical Analysis of Factors Affecting Nanoporous Gold and Its Sensitivity in Comparison with Bulk Gold written by Shruti M. Baharani and published by . This book was released on 2010 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical dealloying has proven to be an efficient way of fabricating nanoporous gold, the morphology of which can be tailored by controlling factors such as the etching time, temperature of electrolyte, composition of the alloy, pre and /or post heat treatment and voltage to suit applications such as fuel cell electrodes and sensors. This work aims at studying the effect of such factors as the electrolyte concentration on the morphology of the emerging material. A model relating the processing parameters and pore size is established by statistical approaches using the Design Expert 7.1 software. An equation that captures the individual as well as interaction effects on nanoporous gold is proposed. The validity of the equation is verified by existing research results. Simulation of this material under applied external load was done to achieve static properties in comparison with bulk gold. The applications where this might be helpful have been mentioned.
Download or read book Nano Architectured and Nanostructured Materials written by Yannick Champion and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book identifies new nanometric architectures that would be of particular interest for applications and the technological route to reach them. Nano-architectures of interest are for optical, electrical, magnetic, mechanical properties and reactivity as well as for specific applications such as catalysis and medical diagnostic and drug delivery. Nano-architectures would be metals, alloys, ceramics, semi-conductors, polymers or hybrids inorganic-polymers materials. The book places special emphasis on crucial technical aspects of the fabrication, the control and the characterisation of complex nano-architectures.
Download or read book Nanoporous Alumina written by Dusan Losic and published by Springer. This book was released on 2015-07-17 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives detailed information about the fabrication, properties and applications of nanoporous alumina. Nanoporous anodic alumina prepared by low-cost, simple and scalable electrochemical anodization process due to its unique structure and properties have attracted several thousand publications across many disciplines including nanotechnology, materials science, engineering, optics, electronics and medicine. The book incorporates several themes starting from the understanding fundamental principles of the formation nanopores and theoretical models of the pore growth. The book then focuses on describing soft and hard modification techniques for surface and structural modification of pore structures to tailor specific sensing, transport and optical properties of nano porous alumina required for diverse applications. These broad applications including optical biosensing, electrochemical DNA biosensing, molecular separation, optofluidics and drug delivery are reviewed in separated book chapters. The book appeals to researchers, industry professionals and high-level students.
Download or read book Mechanical Properties and Fracture Behavior of Nanoporous Au written by J. R. Hayes and published by . This book was released on 2005 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. From a material science point of view, one of the key issues in this context is the synthesis of nanoporous metals with both high tensile and compressive strength. Nanoporous gold (np-Au) has been suggested as a candidate material for this application due to its monolithic character. The material can be synthesized by electrochemically-driven dealloying of Ag-Au alloys, and exhibits an open sponge-like structure of interconnecting ligaments with a typical pore size distribution on the nanometer length scale. However, besides the observation of a ductile-brittle transition very little is known about the mechanical behavior of this material. Here, we present our results regarding the mechanical properties and the fracture behavior of np-Au. Depth-sensing nanoindentation reveals that the yield strength of np-Au is almost one order of magnitude higher than the value predicted by scaling laws developed for macroscopic open-cell foams. The unexpectedly high value of the yield strength indicates the presence of a distinct size effect of the mechanical properties due to the sub-micron dimensions of the ligaments, thus potentially opening a door to a new class of high yield strength--low density materials. The failure mechanism of np-Au under tensile stress was evaluated by microscopic examination of fracture surfaces using scanning electron microscopy. On a macroscopic level, np-Au is a very brittle material. However, microscopically np-Au is very ductile as ligaments strained by as much as 200% can be observed in the vicinity of crack tips. Cell-size effects on the microscopic failure mechanism were studied by annealing experiments whereby increasing the typical pore size/ligament diameter from {approx}100 nm to {approx}1{micro}m.
Download or read book On the Factors Impacting the Mechanical Response of Nanoporous Gold polymer Composites written by Murilo P. Hablitzel and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous gold (NPG) is a bicontinuous network of nanoscale gold ligaments and pores, the dimensions of which can be adjusted to exploit strengthening at small ligament sizes. Nevertheless, its mechanics are limited by the lack of ductility under tensile loading. Recently, the impregnation of the open porous structure with an epoxy phase created a metal-polymer composite that combined strengthening at small structural length-scales with enhanced tensile ductility. The present work aims to clarify the effect of factors influencing the mechanical behaviour of composite materials, particularly the properties of the epoxy phase and interface - properties that are still unexplored in NPG-epoxy composites. To this end, a series of novel approaches were developed to investigate the independent contribution of each factor, focusing on the development of representative model samples, micromechanical testing, and finite element simulation. A novel method to understand the effect of the composite microstructure in the epoxy was made possible by isolating the matrix phase. Taking inspiration from mining techniques, an approach based on gold etching in iodine-iodide solutions successfully leached out the Au from NPG-polymer composites. The remaining bi-continuous open porous polymer (NPP) was investigated using nanoindentation to explore possible size effects as those found in nanoporous gold. The interface was investigated using a model system where a single planar boundary between gold and epoxy was achieved. Using both nanoindentation approaches and novel microshear experiments, the interphase regime and interfacial strength were measured. Moreover, the experimental results inspired a modelling approach of the interfaces for finite element simulations, which was employed to study the interfacial behaviour as a function of the balance between the properties of constituent phases and interfaces. The interfacial model was also employed to simulate the effect of the interfacial strength on the mechanical response and delamination evolution of NPG-epoxy composites. The findings from the investigations on the isolated factors improved the interpretation of the composite mechanical response. No evidence of a structural length-scale effect in the polymer was found, and the response of the isolated polymer phase could be well predicted by an isostrain law applied to the properties measured on the bulk polymer. Furthermore, no evidence supporting the presence of an interlayer was found between the gold and epoxy phases. The measurement of the interfacial strength showed that the interface in NPG-epoxy composite is the weakest link in the composite's deformation, which was also observed in the simulations. The isolated effect of the interfacial properties was attenuated in the composite by the interconnected structure, which in compression allows the load transfer even after interface failure.
Download or read book Nanoporous Gold Characterization Structural Modification and Use as a Solid Support for Biomolecule Immobilization written by Abeera Sharma and published by . This book was released on 2014 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous gold (NPG) has immense technological applications owing to a plethora of properties like large surface area to volume ratio, plasmonic properties, stable gold-thiolate bond formation and a wide range of pore sizes. The surface morphology of nanoporous gold has been altered previously by dealloying and thermal annealing to increase/decrease the pore size and change the surface area. We provide a novel electrochemical annealing technique for post dealloying modification wherein electrochemical sweep cycles in different electrolytes at positive potentials leads to a subsequent increase in pore sizes of nanoporous gold as studied using scanning electron microscopy. Tailoring the surface of nanoporous gold allows us to characterize and study self-assembled monolayers of alkanethiols, including those terminated by carbohydrate moieties. The orientation of these thiols on nanoporous gold is not uniform due to the interconnected framework of pores and ligaments and we try to offer a fair comparison between flat gold and nanoporous gold to determine the surface coverage of these self-assembled monolayers. Carbohydrate-lectin interactions have been studied with the help of dendrimers as linkers. Dendrimers (polyamidoamine generation 4 and 5) have been used as linkers due to their multivalent interactions with carbohydrate moieties and impedance spectroscopy as well as atomic force microscopy techniques have been utilized to study dendrimers attached on nanoporous gold surface using covalent immobilization. This study aims at providing a comprehensive surface property analysis of nanoporous gold.
