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Thermal Transport In Carbon Based Nanomaterials

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Thermal Transport in Carbon Based Nanomaterials

Thermal Transport in Carbon Based Nanomaterials Book
Author : Gang Zhang
Publisher : Elsevier
Release : 2017-06-13
ISBN : 0323473466
Language : En, Es, Fr & De

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Book Description :

Thermal Transport in Carbon-Based Nanomaterials describes the thermal properties of various carbon nanomaterials and then examines their applications in thermal management and renewable energy. Carbon nanomaterials include: one-dimensional (1D) structures, like nanotubes; two-dimensional (2D) crystal lattice with only one-atom-thick planar sheets, like graphenes; composites based on carbon nanotube or graphene, and diamond nanowires and thin films. In the past two decades, rapid developments in the synthesis and processing of carbon-based nanomaterials have created a great desire among scientists to gain a greater understanding of thermal transport in these materials. Thermal properties in nanomaterials differ significantly from those in bulk materials because the characteristic length scales associated with the heat carriers, phonons, are comparable to the characteristic length. Carbon nanomaterials with high thermal conductivity can be applied in heat dissipation. This looks set to make a significant impact on human life and, with numerous commercial developments emerging, will become a major academic topic over the coming years. This authoritative and comprehensive book will be of great use to both the existing scientific community in this field, as well as for those who wish to enter it. Includes coverage of the most important and commonly adopted computational and experimental methods to analyze thermal properties in carbon nanomaterials Contains information about the growth of carbon nanomaterials, their thermal properties, and strategies to control thermal properties and applications, allowing readers to assess how to use each material most efficiently Offers a comprehensive overview of the theoretical background behind thermal transport in carbon nanomaterials

Thermal Behaviour and Applications of Carbon Based Nanomaterials

Thermal Behaviour and Applications of Carbon Based Nanomaterials Book
Author : Dimitrios V. Papavassiliou,Hai M. Duong,Feng Gong
Publisher : Elsevier
Release : 2020-04-15
ISBN : 0128176822
Language : En, Es, Fr & De

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Book Description :

Nanocomposites with Carbon-based nanofillers (e.g., carbon nanotubes, graphene sheets and nanoribbons etc.) form a class of extremely promising materials for thermal applications. In addition to exceptional material properties, the thermal conductivity of the carbon-based nanofillers can be higher than any other known material, suggesting the possibility to engineer nanocomposites that are both lightweight and durable, and have unique thermal properties. This potential is hindered by thermal boundary resistance (TBR) to heat transfer at the interface between nanoinclusions and the matrix, and by the difficulty to control the dispersion pattern and the orientation of the nanoinclusions. Thermal Behaviour and Applications of Carbon-Based Nanomaterials: Theory, Methods and Applications explores heat transfer in nanocomposites, discusses techniques predicting and modeling the thermal behavior of carbon nanocomposites at different scales, and methods for engineering applications of nanofluidics and heat transfer. The chapters combine theoretical explanation, experimental methods and computational analysis to show how carbon-based nanomaterials are being used to optimise heat transfer. The applications-focused emphasis of this book makes it a valuable resource for materials scientists and engineers who want to learn more about nanoscale heat transfer. Offers an informed overview of how carbon nanomaterials are currently used for nanoscale heat transfer Discusses the major applications of carbon nanomaterials for heat transfer in a variety of industry sectors Details the major computational methods for the analysis of the thermal properties of carbon nanomaterials

Thermal Transport in Low Dimensions

Thermal Transport in Low Dimensions Book
Author : Stefano Lepri
Publisher : Springer
Release : 2016-04-07
ISBN : 3319292617
Language : En, Es, Fr & De

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Book Description :

Understanding non-equilibrium properties of classical and quantum many-particle systems is one of the goals of contemporary statistical mechanics. Besides its own interest for the theoretical foundations of irreversible thermodynamics(e.g. of the Fourier's law of heat conduction), this topic is also relevant to develop innovative ideas for nanoscale thermal management with possible future applications to nanotechnologies and effective energetic resources. The first part of the volume (Chapters 1-6) describes the basic models, the phenomenology and the various theoretical approaches to understand heat transport in low-dimensional lattices (1D e 2D). The methods described will include equilibrium and nonequilibrium molecular dynamics simulations, hydrodynamic and kinetic approaches and the solution of stochastic models. The second part (Chapters 7-10) deals with applications to nano and microscale heat transfer, as for instance phononic transport in carbon-based nanomaterials, including the prominent case of nanotubes and graphene. Possible future developments on heat flow control and thermoelectric energy conversion will be outlined. This volume aims at being the first step for graduate students and researchers entering the field as well as a reference for the community of scientists that, from different backgrounds (theoretical physics, mathematics, material sciences and engineering), has grown in the recent years around those themes.

Phonon Thermal Transport in Silicon Based Nanomaterials

Phonon Thermal Transport in Silicon Based Nanomaterials Book
Author : Hai-Peng Li,Rui-Qin Zhang
Publisher : Springer
Release : 2018-11-01
ISBN : 9811326371
Language : En, Es, Fr & De

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Book Description :

In this Brief, authors introduce the advance in theoretical and experimental techniques for determining the thermal conductivity in nanomaterials, and focus on review of their recent theoretical studies on the thermal properties of silicon–based nanomaterials, such as zero–dimensional silicon nanoclusters, one–dimensional silicon nanowires, and graphenelike two–dimensional silicene. The specific subject matters covered include: size effect of thermal stability and phonon thermal transport in spherical silicon nanoclusters, surface effects of phonon thermal transport in silicon nanowires, and defects effects of phonon thermal transport in silicene. The results obtained are supplemented by numerical calculations, presented as tables and figures. The potential applications of these findings in nanoelectrics and thermoelectric energy conversion are also discussed. In this regard, this Brief represents an authoritative, systematic, and detailed description of the current status of phonon thermal transport in silicon–based nanomaterials. This Brief should be a highly valuable reference for young scientists and postgraduate students active in the fields of nanoscale thermal transport and silicon-based nanomaterials.

Experimental Investigations of Thermal Transport in Carbon Nanotubes Graphene and Nanoscale Point Contacts

Experimental Investigations of Thermal Transport in Carbon Nanotubes  Graphene and Nanoscale Point Contacts Book
Author : Michael Thompson Pettes
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

As silicon-based transistor technology continues to scale ever downward, anticipation of the fundamental limitations of ultimately-scaled devices has driven research into alternative device technologies as well as new materials for interconnects and packaging. Additionally, as power dissipation becomes an increasingly important challenge in highly miniaturized devices, both the implementation and verification of high mobility, high thermal conductivity materials, such as low dimensional carbon nanomaterials, and the experimental investigation of heat transfer in the nanoscale regime are requisite to continued progress. This work furthers the current understanding of structure-property relationships in low dimensional carbon nanomaterials, specifically carbon nanotubes (CNTs) and graphene, through use of combined thermal conductance and transmission electron microscopy (TEM) measurements on the same individual nanomaterials suspended between two micro-resistance thermometers. Through the development of a method to measure thermal contact resistance, the intrinsic thermal conductivity, [kappa], of multi-walled (MW) CNTs is found to correlate with TEM observed defect density, linking phonon-defect scattering to the low [kappa] in these chemical vapor deposition (CVD) synthesized nanomaterials. For single- (S) and double- (D) walled (W) CNTs, the [kappa] is found to be limited by thermal contact resistance for the as-grown samples but still four times higher than that for bulk Si. Additionally, through the use of a combined thermal transport-TEM study, the [kappa] of bi-layer graphene is correlated with both crystal structure and surface conditions. Theoretical modeling of the [kappa] temperature dependence allows for the determination that phonon scattering mechanisms in suspended bi-layer graphene with a thin polymeric coating are similar to those for the case of graphene supported on SiO2. Furthermore, a method is developed to investigate heat transfer through a nanoscale point contact formed between a sharp silicon tip and a silicon substrate in an ultra high vacuum (UHV) atomic force microscope (AFM). A contact mechanics model of the interface, combined with a heat transport model considering solid-solid conduction and near-field thermal radiation leads to the conclusion that the thermal resistance of the nanoscale point contact is dominated by solid-solid conduction.

First Principles based Molecular Modeling of Thermal Transport in Silicon based Nanomaterials

First Principles based Molecular Modeling of Thermal Transport in Silicon based Nanomaterials Book
Author : Yongjin Lee
Publisher : Unknown
Release : 2014
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

In today's nanotechnology, a critical issue is to gain the ability to control the structure and function of matter with a deeper understanding of the quantitative and qualitative relationship among their synthesis conditions, structures, and properties. Experiments may provide information regarding the behavior of nanomaterials, but their interpretations are often controversial due largely to the difficulty of direct measurement. Hereupon, with the amazing advance in computer technology since the late 20th century, computational modeling in science and engineering is increasingly important particularly in the fields of nanoscience and nanotechnology while it can provide researchers with significant insights into atomic-level interactions in various materials systems and underlying fundamental theories. The ability of engineering thermal conductivity of materials on the nanoscale has become extremely important in various applications including electronics and energy storage/conversion technologies. Due to technical difficulties in experimentally measuring the thermal conductivity of disordered and complex nanostructures, there has been much interest in use of theoretical and computational methods to investigate thermal transport properties nanostructured materials. One computational method that can perform an accurate analysis for the thermal conductivity of new or complex systems is molecular dynamics (MD), due to its capability of predicting the behaviors of atoms in large systems. In this work, we have developed a comprehensive MD-based computational platform capable of predicting and explaining thermal transport in disordered and complex nanostructured materials. The unique features include construction of realistic nanostructures, determination of reliable force fields, and direct simulation of large systems, which are allowed by coupling various state-of-the-art computational methods including quantum mechanics, molecular mechanics, statistical theories, and massively parallel computing. The computational scheme was applied to describe thermal transport in various silicon and carbon-based disordered and nanostructures. First, the effects of defects including vacancy clusters, substitutional dopants, and dopant-defect complexes on the thermal conductivity of bulk crystalline silicon were investigated. Next, we analyzed the factors affecting heat transport in silicon-germanium and ternary silicon-germanium-tin alloys. Lastly, we performed the analysis of heat transport in silicon-based nanostructures such as nanowires and polycrystalline structures.

Molecular Level Assessment of Thermal Transport and Thermoelectricity in Materials From Bulk Alloys to Nanostructures

Molecular Level Assessment of Thermal Transport and Thermoelectricity in Materials  From Bulk Alloys to Nanostructures Book
Author : Alper Kinaci
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

The ability to manipulate material response to dynamical processes depends on the extent of understanding of transport properties and their variation with chemical and structural features in materials. In this perspective, current work focuses on the thermal and electronic transport behavior of technologically important bulk and nanomaterials. Strontium titanate is a potential thermoelectric material due to its large Seebeck coefficient. Here, first principles electronic band structure and Boltzmann transport calculations are employed in studying the thermoelectric properties of this material in doped and deformed states. The calculations verified that excessive carrier concentrations are needed for this material to be used in thermoelectric applications. Carbon- and boron nitride-based nanomaterials also offer new opportunities in many applications from thermoelectrics to fast heat removers. For these materials, molecular dynamics calculations are used to evaluate lattice thermal transport. To do this, first, an energy moment term is reformulated for periodic boundary conditions and tested to calculate thermal conductivity from Einstein relation in various systems. The influences of the structural details (size, dimensionality) and defects (vacancies, Stone-Wales defects, edge roughness, isotopic disorder) on the thermal conductivity of C and BN nanostructures are explored. It is observed that single vacancies scatter phonons stronger than other type of defects due to unsatisfied bonds in their structure. In pristine states, BN nanostructures have 4-6 times lower thermal conductivity compared to C counterparts. The reason of this observation is investigated on the basis of phonon group velocities, life times and heat capacities. The calculations show that both phonon group velocities and life times are smaller in BN systems. Quantum corrections are also discussed for these classical simulations. The chemical and structural diversity that could be attained by mixing hexagonal boron nitride and graphene provide further avenues for tuning thermal and electronic properties. In this work, the thermal conductivity of hybrid graphene/hexagonal-BN structures: stripe superlattices and BN (graphene) dots embedded in graphene (BN) are studied. The largest reduction in thermal conductivity is observed at 50% chemical mixture in dot superlattices. The dot radius appears to have little effect on the magnitude of reduction around large concentrations while smaller dots are more influential at dilute systems. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149458

Quantitative Mapping of Nanothermal Transport via Scanning Thermal Microscopy

Quantitative Mapping of Nanothermal Transport via Scanning Thermal Microscopy Book
Author : Jean Spièce
Publisher : Springer Nature
Release : 2019-10-18
ISBN : 3030308138
Language : En, Es, Fr & De

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Book Description :

The thesis tackles one of the most difficult problems of modern nanoscale science and technology - exploring what governs thermal phenomena at the nanoscale, how to measure the temperatures in devices just a few atoms across, and how to manage heat transport on these length scales. Nanoscale heat generated in microprocessor components of only a few tens of nanometres across cannot be effectively fed away, thus stalling the famous Moore's law of increasing computer speed, valid now for more than a decade. In this thesis, Jean Spièce develops a novel comprehensive experimental and analytical framework for high precision measurement of heat flows at the nanoscale using advanced scanning thermal microscopy (SThM) operating in ambient and vacuum environment, and reports the world’s first operation of cryogenic SThM. He applies the methodology described in the thesis to novel carbon-nanotube-based effective heat conductors, uncovers new phenomena of thermal transport in two- dimensional (2D) materials such as graphene and boron nitride, thereby discovering an entirely new paradigm of thermoelectric cooling and energy production using geometrical modification of 2D materials.

Carbon Nanomaterials Modeling Design and Applications

Carbon Nanomaterials  Modeling  Design  and Applications Book
Author : Kun Zhou
Publisher : CRC Press
Release : 2019-07-17
ISBN : 1351123564
Language : En, Es, Fr & De

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Book Description :

Carbon Nanomaterials: Modeling, Design, and Applications provides an in-depth review and analysis of the most popular carbon nanomaterials, including fullerenes, carbon nanotubes, graphene and novel carbon nanomaterial-based membranes and thin films, with emphasis on their modeling, design and applications. This book provides basic knowledge of the structures, properties and applications of carbon-based nanomaterials. It illustrates the fundamental structure-property relationships of the materials in both experimental and modeling aspects, offers technical guidance in computational simulation of nanomaterials, and delivers an extensive view on current achievements in research and practice, while presenting new possibilities in the design and usage of carbon nanomaterials. This book is aimed at both undergraduate and graduate students, researchers, designers, professors, and professionals within the fields of materials science and engineering, mechanical engineering, applied physics, and chemical engineering.

Thermal Transport in Individual Nanowires and Nanotubes

Thermal Transport in Individual Nanowires and Nanotubes Book
Author : Deyu Li
Publisher : Unknown
Release : 2002
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Thermal Transport in Individual Nanowires and Nanotubes book written by Deyu Li, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Carbon Nanotubes for Thermal Interface Materials in Microelectronic Packaging

Carbon Nanotubes for Thermal Interface Materials in Microelectronic Packaging Book
Author : Wei Lin
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials.\r : The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials.\r : The major achievements are summarized.\r : 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment, an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon.\r : 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ~35% and ~65%, respectively, in tensile strength (~0.8 GPa) and modulus (~90 GPa) during tensile testing; an ~20% improvement in electrical conductivity (~80000 S m−1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such an microwave annealing process has been extended to the preparation of reduced graphene oxide.\r : 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding.\r : 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ~30 mm2 s−1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ~27 and ~540 W m−1 K−1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing density was beneficial in increasing the collective thermal conductivity of the VACNT film; however, the increased tube-tube interaction in dense VACNT films decreased the thermal conductivity of the individual CNTs. The tip-to-tip contact resistance was shown to be ~1×10−7 m2 K W−1. The study will shed light on the potential application of VACNTs as thermal interface materials in microelectronic packaging.\r : 5. A combined process of in situ functionalization and microwave curing has been developed to effective enhance the interface between carbon nanotubes and the epoxy matrix. Effective medium theory has been used to analyze the interfacial thermal resistance between carbon nanotubes and polymer matrix, and that between graphite nanoplatlets and polymer matrix.

Prediction and Measurement of Thermal Transport Across Interfaces Between Isotropic Solids and Graphitic Materials

Prediction and Measurement of Thermal Transport Across Interfaces Between Isotropic Solids and Graphitic Materials Book
Author : Anonim
Publisher : Unknown
Release : 2010
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Due to the high intrinsic thermal conductivity of carbon allotropes, there have been many attempts to incorporate such structures into existing thermal abatement technologies. In particular, carbon nanotubes (CNTs) and graphitic materials (i.e., graphite and graphene flakes or stacks) have garnered much interest due to the combination of both their thermal and mechanical properties. However, the introduction of these carbon-based nanostructures into thermal abatement technologies greatly increases the number of interfaces per unit length within the resulting composite systems. Consequently, thermal transport in these systems is governed as much by the interfaces between the constituent materials as it is by the materials themselves. This paper reports the behavior of phononic thermal transport across interfaces between isotropic thin films and graphite substrates. Elastic and inelastic diffusive transport models are formulated to aid in the prediction of conductance at a metal-graphite interface. The temperature dependence of the thermal conductance at Au-graphite interfaces is measured via transient thermoreflectance from 78 to 400 K. It is found that different substrate surface preparations prior to thin film deposition have a significant effect on the conductance of the interface between film and substrate.

Novel Carbon nanotube based Interface Materials and Two phase Microchannel Cold Plates for High density Electronics Cooling

Novel Carbon nanotube based Interface Materials and Two phase Microchannel Cold Plates for High density Electronics Cooling Book
Author : Tao Tong
Publisher : Unknown
Release : 2007
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Novel Carbon nanotube based Interface Materials and Two phase Microchannel Cold Plates for High density Electronics Cooling book written by Tao Tong, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Thermal Transport Through Individual Nanostructures and Their Contacts

Thermal Transport Through Individual Nanostructures and Their Contacts Book
Author : Yang Yang
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Thermal Transport Through Individual Nanostructures and Their Contacts book written by Yang Yang, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Static and Dynamic Thermal Behavior of Carbon Based Nanofluids

Static and Dynamic Thermal Behavior of Carbon Based Nanofluids Book
Author : Omar Hashim Al Samarrai,OhioLINK Electronic Theses and Dissertations Center
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Nanofluids are a new class of heat transfer fluids which are engineered by dispersing nanometer-sized solid particles or tubes in conventional heat transfer fluids such as water, ethylene glycol, and engine oil. The first part of this study includes carbon nanotube (CNT)-ethylene glycol (EG) suspension as thermal management fluids. Three types of CNTs with various degrees of crystallinity and surface energy were prepared using heat-treatment temperature. The thermal conductivity of nanofluids tested at varying concentration from 0% to 1.2% using static and dynamic thermal tests. The CNT type and volume concentration were investigated at various shear rates. The thermal resistance of the test suspensions decreased with increasing shear rate. These tests showed that CNT with higher crystallinity and concentration exhibit better thermal performance. However, these CNT tend to break down under high shear. Conversely, CNT with medium crystallinity exhibits the best compromise. The second part of the study includes the formulation of a theoretical model for the effective thermal conductivity of nanofluids. The model is based on a novel point of view regarding the arrangement of nanoparticles in the base fluid. The predictions from the model show a reasonably good agreement with the experimental results.

Annual Review of Materials Research

Annual Review of Materials Research Book
Author : Anonim
Publisher : Unknown
Release : 2009
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Advanced Computational Nanomechanics

Advanced Computational Nanomechanics Book
Author : Nuno Silvestre
Publisher : John Wiley & Sons
Release : 2016-02-08
ISBN : 1119068932
Language : En, Es, Fr & De

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Book Description :

Contains the latest research advances in computational nanomechanics in one comprehensive volume Covers computational tools used to simulate and analyse nanostructures Includes contributions from leading researchers Covers of new methodologies/tools applied to computational nanomechanics whilst also giving readers the new findings on carbon-based aggregates (graphene, carbon-nanotubes, nanocomposites) Evaluates the impact of nanoscale phenomena in materials

Computational Design and Characterization of Silicene Nanostructures for Electrical and Thermal Transport Applications

Computational Design and Characterization of Silicene Nanostructures for Electrical and Thermal Transport Applications Book
Author : Tim H. Osborn
Publisher : Unknown
Release : 2014
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Novel silicene-based nanomaterials are designed and characterized by first principle computer simulations to assess the effects of adsorptions and defects on stability, electronic, and thermal properties. To explore quantum thermal transport in nanostructures a general purpose code based on Green's function formalism is developed. Specifically, we explore the energetics, temperature dependent dynamics, phonon frequencies, and electronic structure associated with lithium chemisorption on silicene. Our results predict the stability of completely lithiated silicene sheets (silicel) in which lithium atoms adsorb on the atom-down sites on both sides of the silicene sheet. Upon complete lithiation, the band structure of silicene is transformed from a zero-gap semiconductor to a 0.368 eV bandgap semiconductor. This new, uniquely stable, two-atom-thick, semiconductor material could be of interest for nanoscale electronic devices. We further explore the electronic tunability of silicene through molecular adsorption of CO, CO2, O2, N2, and H2O on nanoribbons for potential gas sensor applications. We find that quantum conduction is detectibly modified by weak chemisorption of a single CO molecule on a pristine silicene nanoribbon. Moderate binding energies provide an optimal mix of high detectability and recoverability. With Ag contacts attached to a ~ 1 nm silicene nanoribbon, the interface states mask the conductance modulations caused by CO adsorption, emphasizing length effects for sensor applications. The effects of atmospheric gases: nitrogen, oxygen, carbon dioxide, and water, as well as CO adsorption density and edge-dangling bond defects, on sensor functionality are also investigated. Our results reveal pristine silicene nanoribbons as a promising new sensing material with single molecule resolution. Next, the thermal conductance of silicene nanoribbons with and without defects is explored by Non-Equilibrium Green's function method as implemented in our ThermTran program that was developed as part of this Ph.D. research. We reveal that the thermal transmission and conductance of pristine silicene ribbons is systematically reduced upon the introduction of hydrogen and silicon vacancy defects. This suggests that defect engineering and/or doping may provide a viable method for tuning the thermal transport of narrow silicene nanoribbons. Our generalized ThermTran program for calculating thermal transport across pristine, defected, contacted, or interfaced, junctions is demonstrated.

Thermal Transport in Semiconductor Nanowires

Thermal Transport in Semiconductor Nanowires Book
Author : J. Anaya,J. Jiménez,T. Rodríguez
Publisher : Unknown
Release : 2012
ISBN : 9789535108986
Language : En, Es, Fr & De

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Download Thermal Transport in Semiconductor Nanowires book written by J. Anaya,J. Jiménez,T. Rodríguez, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Thermal Phenomena in Nanostructured Materials and Devices

Thermal Phenomena in Nanostructured Materials and Devices Book
Author : Amy Marie Marconnet
Publisher : Unknown
Release : 2012
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Nanostructuring leads to unique material properties and combinations of properties not naturally available in bulk materials. The study of these properties is critical to improving the device performance and reliability for a range of applications including electronics, thermoelectrics, and nanophotonics. This work focuses on efforts to push the thermal conductivity of nanostructured materials to the extremes: the thermal conductivity of carbon nanotubes (CNT) and nanotube-based materials can exceed that of metals, while the introduction of nanoscale boundaries (e.g. nanoscale pores in silicon nanowires) yields extremely low thermal conductivity materials. Furthermore, this nanostructuring also leads to unique combinations of properties. Porous silicon nanowires are a step towards the desired electron-crystal, phonon-glass combination ideal for thermoelectric applications, while thermally-conductive, mechanically-compliant carbon nanotube films for promising for electronics packaging. This work first explores how the high axial thermal conductivity of carbon nanotubes can be leveraged effectively in thin film and composites through detailed understanding of the phonon transport and measurements of CNT-based films. This work then investigates how nanostructuring silicon significantly reduces the thermal conductivity through enhanced boundary scattering and the possibility of phononic crystal effects. Specifically, measurements of individual, porous silicon nanowires and arrays of silicon nanowires show significant reduction in the thermal conductivity compared to bulk silicon. A detailed model for reduced thermal conductivity due to phonon boundary scattering is developed in conjunction with measurements. Finally, this work also examines how the composition and annealing conditions impact both thermal transport and photoluminescence in silicon-rich silicon nitride films.