Author: Johannes Sellmann
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Claes Granqvist
Publisher: Springer Science & Business Media
ISBN: 1402024444
Category : Science
Languages : en
Pages : 194

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Author: Yves Huttel
Publisher: John Wiley & Sons
ISBN: 3527698426
Category : Technology & Engineering
Languages : en
Pages : 416

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The first overview of this topic begins with some historical aspects and a survey of the principles of the gas aggregation method. The second part covers modifications of this method resulting in different specialized techniques, while the third discusses the post-growth treatment that can be applied to the nanoparticles. The whole is rounded off by a review of future perspectives and the challenges facing the scientific and industrial communities. An excellent resource for anyone working with the synthesis of nanoparticles, both in academia and industry.

Author: Axel Lorke
Publisher: Springer Science & Business Media
ISBN: 3642285465
Category : Science
Languages : en
Pages : 425

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Book Description
Gasphase synthesis of nanoparticles and nanostructured materials offers high chemical purity and crystalline quality as well as scalability up to industrial quantities. It is therefore highly attractive for both basic and applied science. This book gives a broad and coherent overview of the complete production and value chain from nanoparticle formation to integration into products and devices. Written by experts in the field – with backgrounds in electrical engineering, experimental and theoretical physics, materials science, and chemical engineering – the book offers a deep insight into the fabrication, characterization and application of nanoparticles from the gasphase. The first part of the book, “Formation”, covers chemical and growth kinetics, in-situ diagnostics, numerical simulation, process development and material deposition. In the second section, the reader is introduced to the structure and dynamics that lead to functional nanoscale systems and materials. The third section, “Properties and Applications”, provides a detailed discussion of the optical, electronic, magnetic and chemical characteristics of nanostructures and demonstrates how these can be used in tailored materials and devices.

Author: Jingkun Jiang
Publisher:
ISBN:
Category :
Languages : en
Pages : 404

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Author: Panagiotis Grammatikopoulos
Publisher: Elsevier
ISBN: 0128214988
Category : Technology & Engineering
Languages : en
Pages : 244

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Due to their small size and their dependence on very fast phenomena, nanomaterials are ideal systems for computational modelling. This book provides an overview of various nanosystems classified by their dimensions: 0D (nanoparticles, QDs, etc.), 1D (nanowires, nanotubes), 2D (thin films, graphene, etc.), 3D (nanostructured bulk materials, devices). Fractal dimensions, such as nanoparticle agglomerates, percolating films and combinations of materials of different dimensionalities are also covered (e.g. epitaxial decoration of nanowires by nanoparticles, i.e. 0D+1D nanomaterials). For each class, the focus will be on growth, structure, and physical/chemical properties. The book presents a broad range of techniques, including density functional theory, molecular dynamics, non-equilibrium molecular dynamics, finite element modelling (FEM), numerical modelling and meso-scale modelling. The focus is on each method’s relevance and suitability for the study of materials and phenomena in the nanoscale. This book is an important resource for understanding the mechanisms behind basic properties of nanomaterials, and the major techniques for computational modelling of nanomaterials. Explores the major modelling techniques used for different classes of nanomaterial Assesses the best modelling technique to use for each different type of nanomaterials Discusses the challenges of using certain modelling techniques with specific nanomaterials

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 63

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Author: Malini Dasgupta
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Markus Sander
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Rickard Gunnarsson
Publisher: Linköping University Electronic Press
ISBN: 9176854663
Category :
Languages : en
Pages : 69

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Book Description
Nanotechnology can profoundly benefit our health, environment and everyday life. In order to make this a reality, both technological and theoretical advancements of the nanomaterial synthesis methods are needed. A nanoparticle is one of the fundamental building blocks in nanotechnology and this thesis describes the control of the nucleation, growth and oxidation of titanium particles produced in a pulsed plasma. It will be shown that by controlling the process conditions both the composition (oxidationstate) and size of the particles can be varied. The experimental results are supported by theoretical modeling. If processing conditions are chosen which give a high temperature in the nanoparticle growth environment, oxygen was found to be necessary in order to nucleate the nanoparticles. The two reasons for this are 1: the lower vapor pressure of a titanium oxide cluster compared to a titanium cluster, meaning a lower probability of evaporation, and 2: the ability of a cluster to cool down by ejecting an oxygen atom when an oxygen molecule condenses on its surface. When the oxygen gas flow was slightly increased, the nanoparticle yield and oxidation state increased. A further increase caused a decrease in particle yield which is attributed to a slight oxidation ofthe cathode. By varying the oxygen flow, it was possible to control the oxidation state of the nanoparticles without fully oxidizing the cathode. Pure titanium nanoparticles could not be produced in a high vacuum system because oxygen containing gases such as residual water vapour have a profound influence on nanoparticle yield and composition. In an ultrahigh vacuum system titanium nanoparticles without significantoxygen contamination were produced by reducing the temperature of the growth environment and increasing the pressure of an argon-helium gas mixture within whichthe nanoparticles grew. The dimer formation rate necessary for this is only achievable at higher pressures. After a dimer has formed, it needs to grow by colliding with a titanium atom followed by cooling by collisions with multiple buffer gas atoms. The condensation event heats up the cluster to a temperature much higher than the gas temperature, where it is during a short time susceptible to evaporation. When the clusters’ internal energy has decreased by collisions with the gas to less than the energy required to evaporate a titanium atom, it is temporarily stable until the next condensation event occurs. The temperature difference by which the cluster has to cool down before it is temporarily stable is exactly as many kelvins as the gas temperature.The addition of helium was found to decrease the temperature of the gas, making it possible for nanoparticles of pure titanium to grow. The process window where this is possible was determined and the results presented opens up new possibilities to synthesize particles with a controlled contamination level and deposition rate.The size of the nanoparticles has been controlled by three means. The first is to change the electrical potential around the growth zone, which allows for size (diameter) control in the order of 25 to 75 nm without influencing the oxygen content of the particles. The second means is by increasing the pressure which decreases the ambipolar diffusion rate of the ions resulting in a higher growth material density. By doing this, the particle size can be increased from 50 to 250 nm, however the oxygen content also increases with increasing pressure when this is done in a high vacuum system. The last means of size control was by adding a helium flow to the process where higher flows resulted in smaller nanoparticle sizes. When changing the pressure in high vacuum, the morphology of the nanoparticles could be controlled. At low pressures, highly faceted near spherical particles were produced. Increasing the pressure caused the formation of cubic particles which appear to ‘fracture’ at higher pressures. At the highest pressure investigated, the particles became poly-crystalline with a cauliflower shape and this morphology was attributed to a lowad atom mobility. The ability to control the size, morphology and composition of the nanoparticles determines the success of applying the process to manufacture devices. In related work presented in this thesis it is shown that 150-200 nm molybdenum particles with cauliflower morphology were found to scatter light in which made them useful in photovoltaic applications, and the size of titanium dioxide nanoparticles were found to influence the selectivity of graphene based gas sensors.