Thermal and Thermoelectric Transport in Organic and Inorganic Nanostructures PDF Download

Author: Annie C. Weathers
Publisher:
ISBN:
Category :
Languages : en
Pages : 148

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Book Description
Thermal transport in nanowires and nanotubes has attached much attention due to their use in various functional devices and their use as a model system for low dimensional transport phenomena. The precise control of the crystal structure, defects, characteristic size, and electronic properties of nanowires has allowed for fundamental studies of phonon and electron transport in a variety of nanoscale systems. The thermal conductivity in nanostructured materials can vary greatly compared to bulk values owing to classical and quantum size effects. In this work, two model systems for investigating fundamental phonon transport were investigated for potential use in thermoelectric and thermal management applications. The thermoelectric properties of twin defect indium arsenide nanowires and the thermal conductivity of polythiophene nanofibers with improved polymer chain crystallinity were measured with a microfabricated measurement device. The effects of twin planes on reducing the mean free path of phonons in indium arsenide and the effects of improved chain alignment in increasing the thermal conductivity in polymer fibers is discussed.

Author: Howard E. Katz
Publisher: World Scientific
ISBN: 1783266066
Category : Technology & Engineering
Languages : en
Pages : 293

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Book Description
"Power generation from environmentally friendly sources has led to surging interest in thermoelectrics. There has been a move toward alternative thermoelectric materials with enhanced performance through materials and structures that utilize common and safer elements and alternative mechanistic approaches while increasing processing latitude and decreasing cost. This wide-ranging volume examines this progress and future prospects with the new technologies, ease of processing and cost as major considerations, and will benefit active researchers, students and others interested in cutting-edge work in thermoelectric materials. Innovative Thermoelectric Materials incorporates the contributions of a group of recognized experts in thermoelectric materials, many of whom were the first to introduce various materials systems into thermoelectric systems. The perspectives brought to this evolving subject will provide important insights on which those developing the field can build, and will inspire new research directions for the future."--Provided by publisher.

Author: Zhiqun Lin
Publisher: Royal Society of Chemistry
ISBN: 1788014707
Category : Science
Languages : en
Pages : 330

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Book Description
This book summarises the significant progress made in organic thermoelectric materials, focusing on effective routes to minimize thermal conductivity and maximize power factor.

Author: Arden Lot Moore
Publisher:
ISBN:
Category :
Languages : en
Pages : 420

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Book Description
This work presents the development and application of analytical, numerical, and experimental methods for the study of thermal and electrical transport in nanoscale systems, with special emphasis on those materials and phenomena which can be important in thermoelectric and semiconductor device applications. Analytical solutions to the Boltzmann transport equation (BTE) using the relaxation time approximation (RTA) are presented and used to study the thermal and electrical transport properties of indium antimonide (InSb), indium arsenide (InAs), bismuth telluride (Bi2Te3), and chromium disilicide (CrSi2) nanowires. Experimental results for the thermal conductivity of single layer graphene supported by SiO2 were analyzed using an RTA-based model and compared to a full quantum mechanical numerical BTE solution which does not rely on the RTA. The ability of these models to explain the measurement results as well as differences between the two approaches are discussed. Alternatively, numerical solutions to the BTE may be obtained statistically through Monte Carlo simulation for complex geometries which may prove intractable for analytical methods. Following this approach, phonon transport in silicon (Si) sawtooth nanowires was studied, revealing that thermal conductivity suppression below the diffuse surface limit is possible. The experimental investigation of energy transport in nanostructures typically involved the use of microfabricated devices or non-contact optical methods. In this work, two such approaches were analyzed to ascertain their thermal behavior and overall accuracy as well as areas for possible improvement. A Raman spectroscopy-based measurement design for investigating the thermal properties of suspended and supported graphene was examined analytically. The resulting analysis provided a means of determining from measurement results the thermal interface conductance, thermal contact resistance, and thermal conductivity of the suspended and supported graphene regions. Previously, microfabricated devices of several different designs have been used to experimentally measure the thermal transport characteristics of nanostructures such as carbon nanotubes, nanowires, and thin films. To ascertain the accuracy and limitations of various microdevice designs and their associated conduction analyses, finite element models were constructed using ANSYS and measurements of samples of known thermal conductance were simulated. It was found that designs with the sample suspended were generally more accurate than those for which the sample is supported on a bridge whose conductance is measured separately. The effects of radiation loss to the environment of certain device designs were also studied, demonstrating the need for radiation shielding to be at temperatures close to that of the device substrate in order to accurately calibrate the resistance thermometers. Using a suspended microdevice like those analyzed using finite element analysis, the thermal conductivities of individual bismuth (Bi) nanowires were measured. The results were correlated with the crystal structure and growth direction obtained by transmission electron microscopy on the same nanowires. Compared to bulk Bi in the same crystal direction, the thermal conductivity of a single-crystal Bi nanowires of 232 nm diameter was found to be 3 - 6 times smaller than bulk between 100 K and 300 K. For polycrystalline Bi nanowires of 74 nm to 255 nm diameter the thermal conductivity was reduced by a factor of 18 - 78 over the same temperature range. Comparable thermal conductivity values were measured for polycrystalline nanowires of varying diameters, suggesting a grain boundary scattering mean free path for all heat carriers in the range of 15 - 40 nm which is smaller than the nanowire diameters. An RTA-based transport model for both charge carriers and phonons was developed which explains the thermal conductivity suppression in the single-crystal nanowire by considering diffuse phonon-surface scattering, partially diffuse surface scattering of electrons and holes, and scattering of phonons and charge carriers by ionized impurities such as oxygen and carbon of a concentration on the order of 1019 cm−3. Using a similar experimental setup, the thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal conductivity) of higher manganese silicide (HMS) nanostructures were investigated. Bulk HMS is a passable high temperature thermoelectric material which possesses a complex crystal structure that could lead to very interesting and useful nanoscale transport properties. The thermal conductivities of HMS nanowires and nanoribbons were found to be reduced by 50 - 60 % compared to bulk values in the same crystal direction for both nanoribbons and nanowires. The measured Seebeck coefficient data was comparable or below that of bulk, suggesting unintentional doping of the samples either during growth or sample preparation. Difficulty in determining the amorphous oxide layer thickness for nanoribbons samples necessitated using the total, oxide-included cross section in the thermal and electrical conductivity calculation. This in turn led to the determined electrical conductivity values representing the lower bound on the actual electrical conductivity of the HMS core. From this approach, the measured electrical conductivity values were comparable or slightly below the lower end of bulk electrical conductivity values. This oxide thickness issue affects the determination of the HMS nanostructure thermoelectric figure of merit ZT as well, though the lower bound values obtained here were found to still be comparable to or slightly smaller than the expected bulk values in the same crystal direction. Analytical modeling also indicates higher doping than in bulk. Overall, HMS nanostructures appear to have the potential to demonstrate measurable size-induced ZT enhancement, especially if optimal doping and control over the crystallographic growth direction can be achieved. However, experimental methods to achieve reliable electrical contact to quality four-probe samples needs to be improved in order to fully investigate the thermoelectric potential of HMS nanostructures.

Author: Xiaodong Wang
Publisher: Springer Science & Business Media
ISBN: 3319020129
Category : Technology & Engineering
Languages : en
Pages : 520

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Book Description
For the efficient utilization of energy resources and the minimization of environmental damage, thermoelectric materials can play an important role by converting waste heat into electricity directly. Nanostructured thermoelectric materials have received much attention recently due to the potential for enhanced properties associated with size effects and quantum confinement. Nanoscale Thermoelectrics describes the theory underlying these phenomena, as well as various thermoelectric materials and nanostructures such as carbon nanotubes, SiGe nanowires, and graphene nanoribbons. Chapters written by leading scientists throughout the world are intended to create a fundamental bridge between thermoelectrics and nanotechnology, and to stimulate readers' interest in developing new types of thermoelectric materials and devices for power generation and other applications. Nanoscale Thermoelectrics is both a comprehensive introduction to the field and a guide to further research, and can be recommended for Physics, Electrical Engineering, and Materials Science departments.

Author: D. Narducci
Publisher: IOS Press
ISBN: 1643681737
Category : Science
Languages : en
Pages : 241

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Book Description
The field of thermoelectricity has continued to develop rapidly in recent years and remains one of the most exciting areas of research for a materials physicist. The need for sustainable energy has added a technological momentum to the challenge of devising materials with exceptional properties such as low thermal conductivity, high electrical conductivity and a large Seebeck coefficient, and has triggered a global, interdisciplinary effort. More recently, research on thermoelectric materials has promoted and motivated a major research endeavor to clarify the factors affecting thermal conductivity in nanostructures as part of a more general effort to apply nanotechnology to enhance the performance of thermoelectric materials for use in thermoelectric generators and coolers. This book contains the lectures presented as Course 207 of the International School of Physics Enrico Fermi, Advances in Thermoelectricity: Foundational Issues, Materials, and Nanotechnology, held in Varenna, Italy from 15 – 20 July 2019. This comprehensive course aimed to provide students with a modern vision of the physics of thermoelectric phenomena, starting from the thermodynamics of thermoelectricity and from the physics of transport processes and demonstrating how material structure and nanostructure, together with defects, have been used to tailor the physical properties of advanced thermoelectrics. Special attention was also given to areas of current research – from spin-caloritronics to charge transport in polymers – and to a selected number of applications for heat recovery. Encompassing the full complexity of modern thermoelectricity and covering the most cogent themes relevant to current research, the book will be of interest to all those working in the field.

Author: Hai-Peng Li
Publisher: Springer
ISBN: 9811326371
Category : Science
Languages : en
Pages : 94

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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.

Author: Jihong Al-Ghalith
Publisher: Springer
ISBN: 3319738828
Category : Science
Languages : en
Pages : 88

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Book Description
The book introduces modern atomistic techniques for predicting heat transfer in nanostructures, and discusses the applications of these techniques on three modern topics. The study of heat transport in screw-dislocated nanowires with low thermal conductivity in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials, and suggests a new route to lower thermal conductivity that could promote thermoelectricity. The study of high-temperature coating composite materials facilitates the understanding of the role played by composition and structural characterization, which is difficult to approach via experiments. And the understanding of the impact of deformations, such as bending and collapsing on thermal transport along carbon nanotubes, is important as carbon nanotubes, due to their exceptional thermal and mechanical properties, are excellent material candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 1

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Author: Veljko Zlatic
Publisher: Springer
ISBN: 9400749848
Category : Science
Languages : en
Pages : 283

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Book Description
Thermoelectric devices could play an important role in making efficient use of our energy resources but their efficiency would need to be increased for their wide scale application. There is a multidisciplinary search for materials with an enhanced thermoelectric responses for use in such devices. This volume covers the latest ideas and developments in this research field, covering topics ranging from the fabrication and characterization of new materials, particularly those with strong electron correlation, use of nanostructured, layered materials and composites, through to theoretical work to gain a deeper understanding of thermoelectric behavior. It should be a useful guide and stimulus to all working in this very topical field.