Download or read book Synthesis and Thermoelectric Properties of Higher Manganese Silicides for Waste Heat Recovery written by Chen, Xi and published by . This book was released on 2015 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric (TE) materials, which can convert temperature gradients directly into electricity and vice versa, have received renewed interest for waste heat recovery and refrigeration applications. Higher manganese silicides (HMS) are promising p-type TE materials due to the abundance of the constituent elements, environmental friendliness, and good chemical stability. The objective of this dissertation is to establish a better understanding of the structure-TE properties relationship of HMS with a complex Nowotny chimney ladder structure. The focus of this work is on the investigations of the phonon dispersion of HMS crystals and the effects of chemical doping and nanostructuring on the TE properties of polycrystalline HMS. HMS crystals have been synthesized by the Bridgeman method for inelastic neutron scattering measurements of the phonon dispersion. In conjunction with density functional theory calculations, the results clearly show the presence of numerous low-lying optical phonon branches, especially an unusually low-energy optical phonon polarization associated with the twisting motions of the Si helical ladders in the Mn chimneys. The obtained phonon dispersion can be used to explain the low and anisotropic thermal conductivity of HMS crystals. (Al,Ge) double doping was found to be effective in modifying the electrical properties of HMS polycrystals. The peak thermoelectric power factor occurs at an optimized hole concentration of 1.8~2.2×1021 cm−3 at room temperature. On the other hand, Re substitution can suppress the lattice thermal conductivity to approach the calculated minimum value corresponding to the amorphous limit. Meanwhile, the thermoelectric power factor does not markedly change at low Re content of x ≤ 0.04 although it drops considerably with increasing Re content. Hence, the peak ZT has been improved to ~0.6 in both systems. The effects of nanostructuring on the TE properties have been studied in the cold-pressed samples and ball-milled samples. The thermal conductivity was reduced remarkably by decreasing the grain size. It is found that the grain size effects are more significant at low temperature. However, it is difficult to reduce the grain size to less than 50 nm without the formation of impurity phases by ball milling. These facts limit the ZT enhancement of the nanostructured HMS at high temperatures in this study.

Download or read book Synthesis and Thermoelectric Properties of Mg2Si Mg2Sn Solid Solutions for Waste Heat Recovery written by Libin Zhang (Ph. D.) and published by . This book was released on 2015 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mg2Si-Mg2Sn solid solutions are promising thermoelectric materials for vehicle waste-heat recovery owing to their high figure-of-merit (ZT), light weight, low cost, and non-toxicity. The optimized ZT of Mg2Si0.4Sn0.6 peaks at ~750 K because its relatively narrow band gap results in the pronounced bipolar thermoelectric transport at higher temperatures. This bipolar transport can be eliminated by widening the band gap via Ge substitution. Sb-doped Mg2Si0.4Sn0.6-yGey (y=0, 0.1, 0.2) compositions have been synthesized and their thermoelectric properties have been measured. The measurement results suggest that the bipolar conduction was effectively suppressed in the Ge-substituted compositions. In addition, a triple-parabolic-band model has been established to extract of the lattice contribution from the total thermal conductivity. The calculation results indicate that Ge substitutions slightly reduce the lattice thermal conductivity of Mg2Si0.4Sn0.6. Mg vacancies can be introduced in Mg2SixSn1-x due to Mg evaporation and oxidation. To understand the role of Mg vacancies on the electronic structure and transport properties, Mg2Si0.4Sn0.6 with various Mg deficiency and Sb doping levels have been synthesized and their transport properties have been investigated. The results suggest that Mg vacancies create localized hole states inside the band gap instead of moving the Fermi level into the valence band as would be predicted by a rigid band model. This hypothesis is confirmed by density-functional theory calculations, which show that the hole states are trapped at Mg vacancies above the valence band. This localized-states model also provides a good interpretation of the electron-hopping transport behavior in Mg2-[greek small letter sigma]SixSn1-x. The thermal stability issue of Mg2SixSn1-x needs to be addressed be fore the material can be applied in practical thermoelectric devices. It was found that the Mg2Si0.4Sn0.6 pellet could be oxidized at 823 K in inert gas atmosphere. The sample's carrier concentration decreases significantly due to the Mg vacancies caused by sample oxidation. It has been demonstrated that the atomic-layer deposited Al2O3 coating can effectively protect Mg2Si0.4Sn0.6 from oxidation in inert gas and even in air. This Al2O3 thin-film coating also provides in situ protection to Mg2SixSn1-x during the laser flash measurement and therefore eliminates the measurement errors that occur to the unprotected samples as a result of sample oxidation and graphite exfoliation.

Download or read book Materials Aspect of Thermoelectricity written by Ctirad Uher and published by CRC Press. This book was released on 2016-11-25 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, novel families of materials have been discovered and significant improvements in classical thermoelectric materials have been made. Thermoelectric generators are now being used to harvest industrial heat waste and convert it into electricity. This is being utilized in communal incinerators, large smelters, and cement plants. Leading car and truck companies are developing thermoelectric power generators to collect heat from the exhaust systems of gasoline and diesel engines. Additionally, thermoelectric coolers are being used in a variety of picnic boxes, vessels used to transport transplant organs, and in air-conditioned seats of mid-size cars. Consisting of twenty-one chapters written by top researchers in the field, this book explores the major advancements being made in the material aspects of thermoelectricity and provides a critical assessment in regards to the broadening of application opportunities for thermoelectric energy conversion.

Download or read book Stability of Manganese Silicides of the HMS Type Alloying Effect on Their Electronic Properties written by Ali Allam and published by . This book was released on 2013 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric materials as electric power generators can be used in many fields, such as the conversion of automobile exhausting heat and industrial waste heat, solar photovoltaic-thermoelectric hybrid power generation, or RTG (Radioisotope thermoelectric generator) for deep space exploration. To date, most of the constituent elements of thermoelectric materials are scarce resource and are toxic, resulting in environmental pollution. Silicide materials have shown to exhibit good thermoelectric performances at high temperature without suffering from the aforementioned drawbacks. Among the silicide compounds, silicon-rich silicides MnSix, with x comprised between 1.71 and 1.75, are particularly interesting for their thermoelectric properties. These so-called higher manganese silicides (HMS) exhibit several tetragonal structures that correspond to Mn4Si7, Mn11Si19, Mn15Si26 and Mn27Si47. In this thesis, we examine from an experimental point of view the stability of these compounds. The investigations have been performed on both bulk and thin film materials. Mn4Si7 seems to be the most interesting HMS for thermoelectric applications; hence various synthesis routes have been explored for this compound. Finally, theoretical calculations, based on density-functional theory and Boltzmann's transport theory, have allowed us to predict the thermoelectric properties of substituted Mn4Si7. The objectives were to find substitutional atoms leading to an improvement of the thermoelectric efficiency of Mn4Si7.

Download or read book Enhanced Power Factor of Higher Manganese Silicide Via Melt Spin Synthesis Method written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on the thermoelectric properties of the Higher Manganese Silicide MnSi1.--5 (HMS) synthesized by means of a one-step non-equilibrium method. The ultrahigh cooling rate generated from the melt-spin technique is found to be effective in reducing second phases, which are inevitable during the traditional solid state diffusion processes. Aside from being detrimental to thermoelectric properties, second phases skew the revealing of the intrinsic properties of this class of materials, for example the optimal level of carrier concentration. With this melt-spin sample, we are able to formulate a simple model based on a single parabolic band that can well describe the carrier concentration dependence of the Seebeck coefficient and power factor of the data reported in the literature. An optimal carrier concentration around 5x1020 cm−3 at 300 K is predicted according to this model. The phase-pure melt-spin sample shows the largest power factor at high temperature, resulting in the highest zT value among the three samples in this paper; the maximum value is superior to those reported in the literatures.

Download or read book Multicomponent Silicides for Thermoelectric Materials written by Jean-Claude Tedenac and published by Springer. This book was released on 2017-06-02 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive review of the current state of the art in silicon compounds for thermoelectric applications. Silicides are materials with good initial thermoelectric properties, which can be enhanced through tuning of their micro- and macrostructure. These compounds present various conduction mechanisms and complex band structures. Moreover, some are isotropic, and others anisotropic, which is highly beneficial for device tailoring. Silicides are a particularly attractive material for sensors, thermoelectric generators, and other applications because they are environmentally friendly, abundant, and low cost. This concise volume covers fundamentals and applications for an audience of materials scientists, chemists, solid-state physicists, and engineers.

Download or read book Applications of Process Engineering Principles in Materials Processing Energy and Environmental Technologies written by Shijie Wang and published by Springer. This book was released on 2017-02-07 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection offers new research findings, innovations, and industrial technological developments in extractive metallurgy, energy and environment, and materials processing. Technical topics included in the book are thermodynamics and kinetics of metallurgical reactions, electrochemical processing of materials, plasma processing of materials, composite materials, ionic liquids, thermal energy storage, energy efficient and environmental cleaner technologies and process modeling. These topics are of interest not only to traditional base ferrous and non-ferrous metal industrial processes but also to new and upcoming technologies, and they play important roles in industrial growth and economy worldwide.

Download or read book Thermoelectric properties of higher manganese silicides written by Dao Y Nhi Truong and published by . This book was released on 2015 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: CE TRAVAIL VISE À COUVRIR UNE VARIÉTÉ D'ASPECTS RELATIFS AU SILICIURE DE MANGANESE (HMS), PAR EXEMPLE, LES COMPOSITES, LES SUBSTITUTIONS, LES MÉTHODES DE SYNTHÈSE, ET LES ÉVOLUTIONS STRUCTURALES. LES COMPOSITES FAITS DE COMPOSÉS À BASE DE HMS ET DE NANO-INCLUSIONS ONT ÉTÉ PRÉPARÉS PAR DEUX PROCÉDURES DIFFÉRENTES, I.E. (I) LA RÉACTION À L'ÉTAT SOLIDE, LE MÉLANGE MANUEL, ET LE PRESSAGE À CHAUD, OU (II) LE BROYAGE À BILLES DANS DES CONDITIONS DOUCES ET LE FRITTAGE RÉACTIF. LA DERNIÈRE APPROCHE A PROUVÉ SON EFFICACITÉ DANS LA PRÉPARATION DES COMPOSITES NANOTUBE DE CARBONE MULTIFEUILLET (MWCNT)/MATÉRIAU À BASE DE HMS, QUI CONTIENNENT PRINCIPALEMENT DES PHASES HMS AVEC UNE RÉPARTITION HOMOGÈNE DE MWCNTS. IL A ÉTÉ DÉMONTRÉ QU' UNE RÉPARTITION FINE DES NANO-INCLUSIONS A JOUÉ UN RÔLE CRUCIAL DANS LA RÉDUCTION DE LA CONDUCTIVITÉ THERMIQUE À TRAVERS L'AMÉLIORATION DE LA DISSIPATION DES PHONONS DANS LES MATÉRIAUX À BASE DE HMS, RÉSULTANT EN UNE AUGMENTATION D'ENVIRON 20% DE L'EFFICACITÉ MAXIMALE POUR LA COMPOSITE MWCNT/MATÉRIAU À BASE DE HMS AVEC 1,0% EN MASSE DE MWCNT. LA SUBSTITUTION DU MOLYBDÈNE, DU TUNGSTÈNE, OU D'ARGENT SUR LES SITES DE Mn, ET DE GERMANIUM OU D'ALUMINIUM SUR LES SITES DE Si, A ÉTÉ ÉTUDIÉE POUR LES MATÉRIAUX À BASE DE HMS. LA MEILLEURE EFFICACITÉ THERMOÉLECTRIQUE ENTRE DIFFÉRENTS TENEURS DE Ge A ÉTÉ OBTENUE DANS LE MÉLANGE DE PHASE DE LA COMPOSITION NON STOECHIOMÉTRIQUE MnSi1.75Ge0.02, QUI A ENSUITE ÉTÉ CHOISI COMME LE MATÉRIAU DE BASE POUR LES AUTRES SUBSTITUTIONS. AUCUNE MODIFICATION ESSENTIELLE DES PROPRIÉTÉS ÉLECTRIQUES N'A ÉTÉ OBSERVÉE, MAIS UNE DIMINUTION IMPORTANTE DE LA CONDUCTIVITÉ THERMIQUE DE RÉSEAU A ÉTÉ OBTENUE EN RAISON D'UNE MEILLEUR DISSIPATION DES PHONONS, AVEC LA PLUS GRANDE RÉDUCTION JUSQU' À 25% POUR LA SUBSTITUTION DU MOLYBDÈNE. LE FACTEUR DE MÉRITE MAXIMALE, ZT, ÉTAIT D'ENVIRON 0,40 POUR LE MATÉRIAU AVEC 2% DE MOLYBDÈNE SUR LES SITES DE Mn. LES VALEURS ZT MAXIMALES VARIANT DE 0,31 À 0,42 ONT ÉTÉ ATTEINTES POUR DIVERSES COMPOSITIONS PRÉPARÉES PAR L'ALLIAGE MÉCANIQUE, LE BROYAGE MÉCANIQUE, ET LE TRAITEMENT THERMIQUE DANS UN FOUR CONVENTIONNEL, AINSI QUE PAR LA RÉACTION À L'ÉTAT SOLIDE, QUI POURRAIENT ÊTRE AMÉLIORÉES PAR ÉLIMINER COMPLÈTEMENT LES PRODUITS SECONDAIRES. PAR LA SUITE, UN PROCESSUS SIMPLE ET EFFICACE A ÉTÉ UTILISÉ POUR LA SYNTHÈSE DE HMS NON DOPÉ, IMPLIQUANT LE BROYAGE À BILLES AVEC N-HEXANE DANS DES CONDITIONS DOUCES POUR OBTENIR DES MÉLANGE HOMOGÈNES D'ÉLÉMENTS CONSTITUTIFS, ET LE FRITTAGE FLASH SUBSÉQUENTE POUR LA RÉACTION DIRECTE À L'ÉTAT SOLIDE. LES PARTICULES FINES OBTENUES APRÈS LE BROYAGE AVEC N-HEXANE ONT PERMIS D'AMÉLIORER LE TAUX DE RÉACTION PLUS TARD, RÉSULTANT DES MATÉRIAUX PURS DE HMS. EN CONSÉQUENCE, LE FACTEUR DE MÉRITE MAXIMAL ÉTAIT DE 0,55 À 850 K, UNE VALEUR ÉLEVÉE POUR UN HMS NON DOPÉ. DE PLUS, LES MONOCRISTAUX DE HMS ONT ÉTÉ PRÉPARÉS EN UTILISANT LE TRANSPORT CHIMIQUE EN PHASE VAPEUR À TRÈS FAIBLE RENDEMENT, MAIS LEURS MAUVAISES QUALITÉS ENTRAÎNÉ EN BASSE RÉSOLUTION DE DIFFRACTION DES RAYONS X SUR MONOCRISTAUX. LES MATÉRIAUX À BASE DE HMS, Y COMPRIS CEUX AVEC DES RATIOS ATOMIQUES Si/Mn DIFFÉRENTS ET DIVERS DOPANTS, PAR EXEMPLE, Ge, Al, Cr ET Mo, ONT ÉTÉ PRÉPARÉS POUR ETUDIER L'ÉVOLUTION STRUCTURALE ENGENDREE PAR UNE AUGMENTATION DE LA TEMPÉRATURE. LA FORMULE STRUCTURALE MOYENNE À LA TEMPÉRATURE AMBIANTE ET SA DÉPENDANCE DE LA TEMPÉRATURE ONT ÉTÉ FORTEMENT INFLUENCÉE PAR LA COMPOSITION DES MATÉRIAUX DE DÉPART AINSI QUE PAR LA NATURE DES DOPANTS. LES MESURES DES PROPRIÉTÉS PHYSIQUES SUR LE COMPOSÉ MnSi1.75 ONT RÉVÉLÉ QU'UNE CORRÉLATION ENTRE LES PROPRIÉTÉS THERMOÉLECTRIQUES ET LA FORMULE STRUCTURALE MOYENNE DES MATÉRIAUX À BASE DE HMS POURRAIT ÊTRE ATTENDU.

Download or read book Higher Manganese Silicide as a Thermoelectric Material written by Yatir Sadia and published by . This book was released on 2013 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Materials Aspect of Thermoelectricity written by Ctirad Uher and published by CRC Press. This book was released on 2016-11-25 with total page 625 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, novel families of materials have been discovered and significant improvements in classical thermoelectric materials have been made. Thermoelectric generators are now being used to harvest industrial heat waste and convert it into electricity. This is being utilized in communal incinerators, large smelters, and cement plants. Leading car and truck companies are developing thermoelectric power generators to collect heat from the exhaust systems of gasoline and diesel engines. Additionally, thermoelectric coolers are being used in a variety of picnic boxes, vessels used to transport transplant organs, and in air-conditioned seats of mid-size cars. Consisting of twenty-one chapters written by top researchers in the field, this book explores the major advancements being made in the material aspects of thermoelectricity and provides a critical assessment in regards to the broadening of application opportunities for thermoelectric energy conversion.

Download or read book Thermoelectric Materials and Devices written by Lidong Chen and published by Elsevier. This book was released on 2020-09-25 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric Materials and Devices summarizes the latest research achievements over the past 20 years of thermoelectric material and devices, most notably including new theory and strategies of thermoelectric materials design and the new technology of device integration. The book's author has provided a bridge between the knowledge of basic physical/chemical principles and the fabrication technology of thermoelectric materials and devices, providing readers with research and development strategies for high performance thermoelectric materials and devices. It will be a vital resource for graduate students, researchers and technologists working in the field of energy conversion and the development of thermoelectric devices. - Discusses the new theory and methods of thermoelectric materials design - Combines scientific principles, along with synthesis and fabrication technologies in thermoelectric materials - Presents the design optimization and interface technology for thermoelectric devices - Introduces thermoelectric polymers and organic-inorganic thermoelectric composites

Download or read book Modules Systems and Applications in Thermoelectrics written by David Michael Rowe and published by CRC Press. This book was released on 2012-04-25 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprising two volumes, Thermoelectrics and Its Energy Harvesting reviews the dramatic improvements in technology and application of thermoelectric energy with a specific intention to reduce and reuse waste heat and improve novel techniques for the efficient acquisition and use of energy. This volume, Modules, Systems and Applications in Thermoelectrics, discusses the practical, novel, and truly groundbreaking applications of thermoelectrics in a range of markets. The book details the U.S. interest in alternative energy and energy harvesting, specifically, the current efforts to use thermoelectric generators (TGs) to reduce emissions. Internationally, it expounds on the strong interest in Japan, Korea and Europe to incorporate TGs in cars to reduce fuel consumption and meet EU carbon dioxide emission targets; the European plans to build an isotopic powered thermoelectric generator; and India’s use of TG s in converting hot water from steel mills into electricity.

Download or read book Thermoelectric Nanomaterials written by Kunihito Koumoto and published by Springer Science & Business Media. This book was released on 2013-07-20 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presently, there is an intense race throughout the world to develop good enough thermoelectric materials which can be used in wide scale applications. This book focuses comprehensively on very recent up-to-date breakthroughs in thermoelectrics utilizing nanomaterials and methods based in nanoscience. Importantly, it provides the readers with methodology and concepts utilizing atomic scale and nanoscale materials design (such as superlattice structuring, atomic network structuring and properties control, electron correlation design, low dimensionality, nanostructuring, etc.). Furthermore, also indicates the applications of thermoelectrics expected for the large emerging energy market. This book has a wide appeal and application value for anyone being interested in state-of-the-art thermoelectrics and/or actual viable applications in nanotechnology.

Download or read book Thermoelectric Skutterudites written by Ctirad Uher and published by CRC Press. This book was released on 2021-05-18 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: • Gives a comprehensive account of all fundamental physical properties of skutterudites. • Each major topic is accompanied by introductory sections and further detailed theoretical treatment is provided in Appendices. • Supported by many figures and a vast number of relevant references.

Download or read book Properties of Metal Silicides written by Karen Maex and published by Institution of Electrical Engineers. This book was released on 1995 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: The properties of silicon alloyed with metals are presented here for silicides of both transition and rare earth metals.

Download or read book Mechanochemistry in Nanoscience and Minerals Engineering written by Peter Balaz and published by Springer Science & Business Media. This book was released on 2008-10-20 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanochemistry as a branch of solid state chemistry enquires into processes which proceed in solids due to the application of mechanical energy. This provides a thorough, up to date overview of mechanochemistry of solids and minerals. Applications of mechanochemistry in nanoscience with special impact on nanogeoscience are described. Selected advanced identification methods, most frequently applied in nanoscience, are described as well as the advantage of mechanochemical approach in minerals engineering. Examples of industrial applications are given. Mechanochemical technology is being applied in many industrial fields: powder metallurgy (synthesis of nanometals, alloys and nanocompounds), building industry (activation of cements), chemical industry (solid waste treatment, catalyst synthesis, coal ashes utilization), minerals engineering (ore enrichment, enhancement of processes of extractive metallurgy), agriculture industry (solubility increase of fertilizers), and pharmaceutical industry (improvement of solubility and bioavailability of drugs). This reference serves as an introduction to newcomers to mechanochemistry, and encourages more experienced researchers to broaden their knowledge and discover novel applications in the field.

Download or read book Thermoelectricity and Advanced Thermoelectric Materials written by Ranjan Kumar and published by Woodhead Publishing. This book was released on 2021-06-03 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectricity and Advanced Thermoelectric Materials reviews emerging thermoelectric materials, including skutterudites, clathrates, and half-Heusler alloys. In addition, the book discusses a number of oxides and silicides that have promising thermoelectric properties. Because 2D materials with high figures of merit have emerged as promising candidates for thermoelectric applications, this book presents an updated introduction to the field of thermoelectric materials, including recent advances in materials synthesis, device modeling, and design. Finally, the book addresses the theoretical difficulties and methodologies of computing the thermoelectric properties of materials that can be used to understand and predict highly efficient thermoelectric materials. This book is a key reference for materials scientists, physicists, and engineers in energy. - Reviews the most relevant, emerging thermoelectric materials, including 2D materials, skutterudites, clathrates and half-Heusler alloys - Focuses on how electronic structure engineering can lead to improved materials performance for thermoelectric energy conversion applications - Includes the latest advances in the synthesis, modeling and design of advanced thermoelectric materials