Дисертації з теми "Carbon nano structures"
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Ghoman, Baljinder Singh. "Hydrogen storage in tubular carbon nano-structures." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611507.
Повний текст джерелаGajbhiye, Sachin Omraj. "Multiscale dynamic analysis of carbon nano-structures and nanocomposites." Thesis, IIT Delhi, 2016. http://eprint.iitd.ac.in:80//handle/2074/8197.
Повний текст джерелаPulikollu, Rajasekhar Venkata. "Nano-Coatings on Carbon Structures for Interfacial Modification." Wright State University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=wright1135882817.
Повний текст джерелаPozegic, Thomas R. "Nano-modified carbon-epoxy composite structures for aerospace applications." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809603/.
Повний текст джерелаHu, Wenchong. "FABRICATION OF VERTICALLY ALIGNED CARBON NANOTUBES AND HORIZONTAL NANO-STRUCTURES." UKnowledge, 2002. http://uknowledge.uky.edu/gradschool_theses/241.
Повний текст джерелаHu, Wenchong. "Fabrication of vertically aligned carbon nanotudes and horizontal nano-structures." Lexington, Ky. : [University of Kentucky Libraries], 2002. http://lib.uky.edu/ETD/ukyelen2002t00064/hwcthes.pdf.
Повний текст джерелаTitle from document title page. Document formatted into pages; contains x, 84 p. : ill. Includes abstract. Includes bibliographical references (p. 76-82).
Lee, Chia-Hua. "Carbon nanotube assisted formation of sub-50 nm polymeric nano-structures." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45388.
Повний текст джерелаIncludes bibliographical references (p. 39-43).
A novel processing method was developed for sub-50 nm structures by integrating quantum dots (QDs) on patterned polymer substrates. Poly(styrene-alt-maleic anhydride) (PSMa) was prepared by the initiated chemical vapor deposition (iCVD) method, an alternative to spin-on deposition. The sub-50 nm PSMa polymer patterns were prepared by low energy oxygen plasma etching by using CNTs as the masks. The water soluble, amine-functionalized QDs underwent the nucleophilic acyl substitution reaction with the PSMa containing anhydride functional groups. This integration method is use to incorporate high performance QDs on inexpensive, lightweight flexible substrate.
by Chia-Hua Lee.
S.M.
Dong, S., D. Wang, Ashraf F. Ashour, B. Han, and J. Ou. "Nickel plated carbon nanotubes reinforcing concrete composites: from nano/micro structures to macro mechanical properties." Elsevier, 2020. http://hdl.handle.net/10454/18205.
Повний текст джерелаOwing to their small size, good wettability, uniform dispersion ability and high thermal properties, the nickel-plated carbon nanotubes (Ni-CNTs) with different aspect ratios are used to reinforce reactive powder concrete (RPC) through modifying the nano/micro- structural units of concrete. Incorporating only 0.075 vol% of Ni-CNTs (0.03 vol% of CNTs) can significantly increase mechanical properties of RPC. The enhancement effect on compressive strength caused by the incorporation of Ni-CNTs with aspect ratio of 1000 reaches 26.8%/23.0 MPa, mainly benefiting from the high polymerization C-S-H gels, low porosity, and refined pore structure. The 33.5%/1.92 MPa increases of flexural strength can be attributed to the decrease of large pore, original cracks, molar ratio of CaO to SiO2, and gel water content when Ni-CNTs with aspect ratio of 125 are added. Ni-CNTs with aspect ratio of 1500 have the largest utilization rate of being pulled-out, resulting from the improvement of dispersibility and the pining effect of nickel coating and then leading to the increased toughness. Therefore, incorporating Ni-CNTs can fundamentally modify the nano/micro- scale structural nature of RPC, providing a bottom-up approach for controlling the properties of RPC.
Funding supported from the National Science Foundation of China (51908103 and 51978127) and the China Postdoctoral Science Foundation (2019M651116).
The full-text of this article will be released for public view at the end of the publisher embargo on 7th Dec 2021.
Cox, Barry James. "Mathematical modelling of nano-scaled structures, devices and materials." Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080129.102240/index.html.
Повний текст джерелаMahajan, Amit. "Ferroelectric : CNTs structures fabrication for advanced functional nano devices." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14148.
Повний текст джерелаThis work is about the combination of functional ferroelectric oxides with Multiwall Carbon Nanotubes for microelectronic applications, as for example potential 3 Dimensional (3D) Non Volatile Ferroelectric Random Access Memories (NVFeRAM). Miniaturized electronics are ubiquitous now. The drive to downsize electronics has been spurred by needs of more performance into smaller packages at lower costs. But the trend of electronics miniaturization challenges board assembly materials, processes, and reliability. Semiconductor device and integrated circuit technology, coupled with its associated electronic packaging, forms the backbone of high-performance miniaturized electronic systems. However, as size decreases and functionalization increases in the modern electronics further size reduction is getting difficult; below a size limit the signal reliability and device performance deteriorate. Hence miniaturization of siliconbased electronics has limitations. On this background the Road Map for Semiconductor Industry (ITRS) suggests since 2011 alternative technologies, designated as More than Moore; being one of them based on carbon (carbon nanotubes (CNTs) and graphene) [1]. CNTs with their unique performance and three dimensionality at the nano-scale have been regarded as promising elements for miniaturized electronics [2]. CNTs are tubular in geometry and possess a unique set of properties, including ballistic electron transportation and a huge current caring capacity, which make them of great interest for future microelectronics [2]. Indeed CNTs might have a key role in the miniaturization of Non Volatile Ferroelectric Random Access Memories (NVFeRAM). Moving from a traditional two dimensional (2D) design (as is the case of thin films) to a 3D structure (based on a tridimensional arrangement of unidimensional structures) will result in the high reliability and sensing of the signals due to the large contribution from the bottom electrode. One way to achieve this 3D design is by using CNTs. Ferroelectrics (FE) are spontaneously polarized and can have high dielectric constants and interesting pyroelectric, piezoelectric, and electrooptic properties, being a key application of FE electronic memories. However, combining CNTs with FE functional oxides is challenging. It starts with materials compatibility, since crystallization temperature of FE and oxidation temperature of CNTs may overlap. In this case low temperature processing of FE is fundamental. Within this context in this work a systematic study on the fabrication of CNTs - FE structures using low cost low temperature methods was carried out. The FE under study are comprised of lead zirconate titanate (Pb1-xZrxTiO3, PZT), barium titanate (BaTiO3, BT) and bismuth ferrite (BiFeO3, BFO). The various aspects related to the fabrication, such as effect on thermal stability of MWCNTs, FE phase formation in presence of MWCNTs and interfaces between the CNTs/FE are addressed in this work. The ferroelectric response locally measured by Piezoresponse Force Microscopy (PFM) clearly evidenced that even at low processing temperatures FE on CNTs retain its ferroelectric nature. The work started by verifying the thermal decomposition behavior under different conditions of the multiwall CNTs (MWCNTs) used in this work. It was verified that purified MWCNTs are stable up to 420 ºC in air, as no weight loss occurs under non isothermal conditions, but morphology changes were observed for isothermal conditions at 400 ºC by Raman spectroscopy and Transmission Electron Microscopy (TEM). In oxygen-rich atmosphere MWCNTs started to oxidized at 200 ºC. However in argon-rich one and under a high heating rate MWCNTs remain stable up to 1300 ºC with a minimum sublimation. The activation energy for the decomposition of MWCNTs in air was calculated to lie between 80 and 108 kJ/mol. These results are relevant for the fabrication of MWCNTs – FE structures. Indeed we demonstrate that PZT can be deposited by sol gel at low temperatures on MWCNTs. And particularly interesting we prove that MWCNTs decrease the temperature and time for formation of PZT by ~100 ºC commensurate with a decrease in activation energy from 68±15 kJ/mol to 27±2 kJ/mol. As a consequence, monophasic PZT was obtained at 575 ºC for MWCNTs - PZT whereas for pure PZT traces of pyrochlore were still present at 650 ºC, where PZT phase formed due to homogeneous nucleation. The piezoelectric nature of MWCNTs - PZT synthesised at 500 ºC for 1 h was proved by PFM. In the continuation of this work we developed a low cost methodology of coating MWCNTs using a hybrid sol-gel / hydrothermal method. In this case the FE used as a proof of concept was BT. BT is a well-known lead free perovskite used in many microelectronic applications. However, synthesis by solid state reaction is typically performed around 1100 to 1300 ºC what jeopardizes the combination with MWCNTs. We also illustrate the ineffectiveness of conventional hydrothermal synthesis in this process due the formation of carbonates, namely BaCO3. The grown MWCNTs - BT structures are ferroelectric and exhibit an electromechanical response (15 pm/V). These results have broad implications since this strategy can also be extended to other compounds of materials with high crystallization temperatures. In addition the coverage of MWCNTs with FE can be optimized, in this case with non covalent functionalization of the tubes, namely with sodium dodecyl sulfate (SDS). MWCNTs were used as templates to grow, in this case single phase multiferroic BFO nanorods. This work shows that the use of nitric solvent results in severe damages of the MWCNTs layers that results in the early oxidation of the tubes during the annealing treatment. It was also observed that the use of nitric solvent results in the partial filling of MWCNTs with BFO due to the low surface tension (<119 mN/m) of the nitric solution. The opening of the caps and filling of the tubes occurs simultaneously during the refluxing step. Furthermore we verified that MWCNTs have a critical role in the fabrication of monophasic BFO; i.e. the oxidation of CNTs during the annealing process causes an oxygen deficient atmosphere that restrains the formation of Bi2O3 and monophasic BFO can be obtained. The morphology of the obtained BFO nano structures indicates that MWCNTs act as template to grow 1D structure of BFO. Magnetic measurements on these BFO nanostructures revealed a week ferromagnetic hysteresis loop with a coercive field of 956 Oe at 5 K. We also exploited the possible use of vertically-aligned multiwall carbon nanotubes (VA-MWCNTs) as bottom electrodes for microelectronics, for example for memory applications. As a proof of concept BiFeO3 (BFO) films were in-situ deposited on the surface of VA-MWCNTs by RF (Radio Frequency) magnetron sputtering. For in situ deposition temperature of 400 ºC and deposition time up to 2 h, BFO films cover the VA-MWCNTs and no damage occurs either in the film or MWCNTs. In spite of the macroscopic lossy polarization behaviour, the ferroelectric nature, domain structure and switching of these conformal BFO films was verified by PFM. A week ferromagnetic ordering loop was proved for BFO films on VA-MWCNTs having a coercive field of 700 Oe. Our systematic work is a significant step forward in the development of 3D memory cells; it clearly demonstrates that CNTs can be combined with FE oxides and can be used, for example, as the next 3D generation of FERAMs, not excluding however other different applications in microelectronics.
Este trabalho é sobre a combinação de óxidos ferroelétricos funcionais com nanotubos de carbono (CNTs) para aplicações na microeletrónica, como por exemplo em potenciais memórias ferroelétricas não voláteis (Non Volatile Ferroelectric Random Access Memories (NV-FeRAM)) de estrutura tridimensional (3D). A eletrónica miniaturizada é nos dias de hoje omnipresente. A necessidade de reduzir o tamanho dos componentes eletrónicos tem sido estimulada por necessidades de maior desempenho em dispositivos de menores dimensões e a custos cada vez mais baixos. Mas esta tendência de miniaturização da eletrónica desafia consideravelmente os processos de fabrico, os materiais a serem utilizados nas montagens das placas e a fiabilidade, entre outros aspetos. Dispositivos semicondutores e tecnologia de circuitos integrados, juntamente com a embalagem eletrónica associada, constituem a espinha dorsal dos sistemas eletrónicos miniaturizados de alto desempenho. No entanto, à medida que o tamanho diminui e a funcionalização aumenta, a redução das dimensões destes dipositivos é cada vez mais difícil; é bem conhecido que abaixo de um tamanho limite o desempenho do dispositivo deteriora-se. Assim, a miniaturização da eletrónica à base de silício tem limitações. É precisamente neste contexto que desde 2011 o Road Map for Semiconductor Industry (ITRS) sugere tecnologias alternativas às atualmente em uso, designadas por Mais de Moore (More than Moore); sendo uma delas com base em carbono (CNTs e grafeno) [1]. Os CNTs com o seu desempenho único e tridimensionalidade à escala nanométrica, foram considerados como elementos muito promissores para a eletrónica miniaturizada [2]. Nanotubos de carbono possuem uma geometria tubular e um conjunto único de propriedades, incluindo o transporte balístico de eletrões e uma capacidade enorme de transportar a corrente elétrica, o que os tornou de grande interesse para o futuro da microeletrónica [2]. Na verdade, os CNTs podem ter um papel fundamental na miniaturização das memórias ferroelétricas não voláteis (NV-FeRAM). A mudança de uma construção tradicional bidimensional (2D) (ou seja, a duas dimensões, como são os filmes finos) para uma construção tridimensional 3D, com base num arranjo tridimensional de estruturas unidimensionais (1D), como são as estruturas nanotubulares, resultará num desempenho melhorado com deteção de sinal elétrico optimizada, devido à grande contribuição do elétrodo inferior. Uma maneira de conseguir esta configuração 3D é usando nanotubos de carbono. Os materiais ferroelétricos (FE) são polarizados espontaneamente e possuem constantes dielétricas altas e as suas propriedades piroelétricas, piezoelétricas e eletroópticas tornam-nos materiais funcionais importantes na eletrónica, sendo uma das suas aplicações chave em memórias eletrónicas. No entanto, combinar os nanotubos de carbono com óxidos FE funcionais é um desafio. Começa logo com a compatibilidade entre os materiais e o seu processamento, já que as temperaturas de cristalização do FE e as temperaturas de oxidação dos CNTs se sobrepõem. Neste caso, o processamento a baixa temperatura dos óxidos FE é absolutamente fundamental. Dentro deste contexto, neste trabalho foi realizado um estudo sistemático sobre a fabricação e caracterização estruturas combinadas de CNTs – FE, usando métodos de baixa temperatura e de baixo custo. Os FE em estudo foram compostos de titanato zirconato de chumbo (Pb1-xZrxTiO3, PZT), titanato de bário (BaTiO3, BT) e ferrite de bismuto (BiFeO3, BFO). Os diversos aspetos relacionados com a síntese e fabricação, como efeito sobre a estabilidade térmica dos nanotubos de carbono multiparede (multiwall CNTs, MWCNTs), formação da fase FE na presença de MWCNTs e interfaces entre CNTs / FE foram abordados neste trabalho. A resposta ferroelétrica medida localmente através de microscopia de ponta de prova piezoelétrica (Piezoresponse Force Microscopy (PFM)), evidenciou claramente que, mesmo para baixas temperaturas de processamento óxidos FE sobre CNTs mantém a sua natureza ferroelétrica. O trabalho começou pela identificação do comportamento de decomposição térmica em diferentes condições dos nanotubos utilizados neste trabalho. Verificou-se que os MWCNTs purificados são estáveis até 420 ºC no ar, já que não ocorre perda de peso sob condições não isotérmicas, mas foram observadas, por espectroscopia Raman e microscopia eletrónica de transmissão (TEM), alterações na morfologia dos tubos para condições isotérmicas a 400 ºC. Em atmosfera rica em oxigénio os MWCNTs começam a oxidar-se a 200 ºC. No entanto, em atmosfera rica em árgon e sob uma taxa de aquecimento elevada os MWCNTs permanecem estáveis até 1300 ºC com uma sublimação mínima. A energia de ativação para a decomposição destes MWCNTs em ar foi calculada situar-se entre 80 e 108 kJ / mol. Estes resultados são relevantes para a fabricação de estruturas MWCNTs - FE. De facto, demonstramos que o PZT pode ser depositado por sol-gel a baixas temperaturas sobre MWCNTs. E, particularmente interessante foi provar que a presença de MWCNTs diminui a temperatura e tempo para a formação de PZT, em cerca de ~ 100 ºC comensuráveis com uma diminuição na energia de ativação de 68 ± 15 kJ / mol a 27 ± 2 kJ / mol. Como consequência, foi obtido PZT monofásico a 575 ºC para as estruturas MWCNTs – PZT, enquanto que para PZT (na ausência de MWCNTs) a presença da fase de pirocloro era ainda notória a 650 ºC e onde a fase de PZT foi formada por nucleação homogénea. A natureza piezoelétrica das estruturas de MWCNTs - PZT sintetizadas a 500 ºC por 1 h foi provada por PFM. Na continuação deste trabalho foi desenvolvida uma metodologia de baixo custo para revestimento de MWCNTs usando uma combinação entre o processamento sol – gel e o processamento hidrotermal. Neste caso o FE usado como prova de conceito foi o BT. BT é uma perovesquita sem chumbo bem conhecida e utilizada em muitas aplicações microeletrónicas. No entanto, a síntese por reação no estado sólido é normalmente realizada entre 1100 - 1300 ºC o que coloca seriamente em risco a combinação com MWCNTs. Neste âmbito, também se ilustrou claramente a ineficácia da síntese hidrotérmica convencional, devido à formação de carbonatos, nomeadamente BaCO3. As estruturas MWCNTs - BT aqui preparadas são ferroelétricas e exibem resposta electromecânica (15 pm / V). Considera-se que estes resultados têm impacto elevado, uma vez que esta estratégia também pode ser estendida a outros compostos de materiais com elevadas temperaturas de cristalização. Além disso, foi também verificado no decurso deste trabalho que a cobertura de MWCNTs com FE pode ser optimizada, neste caso com funcionalização não covalente dos tubos, ou seja, por exemplo com sodium dodecyl sulfate (SDS).
Sosina, Sobambo. "Analysis, Modeling, and Optimal Experimental Design under Uncertainty: From Carbon Nano-Structures to 3D Printing." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493439.
Повний текст джерелаStatistics
Malcioglu, Osman Baris. "Tailoring One Dimensional Novel Nano Structures For Specific Applications Using Tools Of Molecular Modeling." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609422/index.pdf.
Повний текст джерелаEl-Abed, Haidar. "First-Principles investigations of carbon-based structures for moletronics, twistronics, superconductivity, and gas-sensing nano-electronic devices." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28855.
Повний текст джерелаKiaei, Kimia. "Hierarchical carbon structures with vertically- aligned nanotube carpets for oil-water separation under different conditions." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1567700408926846.
Повний текст джерелаFechete, Alexandru Constantin, and e54372@ems rmit edu au. "Layered Surface Acoustic Wave Based Gas Sensors Utilising Nanostructured Indium Oxide Thin Layer." RMIT University. Electrical and Computer Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091105.141111.
Повний текст джерелаKube, Pierre [Verfasser], Robert [Akademischer Betreuer] Schlögl, Robert [Gutachter] Schlögl, Reinhard [Gutachter] Schomäcker, and Klaus [Gutachter] Rademann. "Comparison of alkane activation over supported and bulk transition metal oxide catalysts and transition metal free carbon nano structures / Pierre Kube ; Gutachter: Robert Schlögl, Reinhard Schomäcker, Klaus Rademann ; Betreuer: Robert Schlögl." Berlin : Technische Universität Berlin, 2018. http://d-nb.info/1166752380/34.
Повний текст джерелаDuplock, Elizabeth. "First principles study of structure-property relationships in nano-structured carbon materials." Thesis, University of Kent, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429796.
Повний текст джерелаMartin, Jeffrey Brendan. "Electrochemical applications of nano-structured carbons." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/electrochemical-applications-of-nanostructured-carbons(e4c514d1-29e4-460e-9d53-34f75dca0ffa).html.
Повний текст джерелаPham, Kien Cuong. "Nano-structured carbon materials for energy generation and storage." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/33734.
Повний текст джерелаHuang, Peihua. "On-chip micro-supercapacitors based on nano-structured carbon materials." Toulouse 3, 2013. http://www.theses.fr/2013TOU30342.
Повний текст джерелаThe increasing number of functions in portable electronic devices requires more and more energy and power within a limited space. Li-ion thin film or so-called micro-batteries are the current solution for power supply. Drawbacks of these storage elements are poor power performance with limited life-span and temperature range. Carbon-based micro- supercapacitors, on the other hand, are able to deliver energy in short time, thus offering high power capability, to work at low temperature and they present an unlimited life-span. This thesis proposes several carbon-based micro-supercapacitors, to be integrated on a silicon substrate together with other electronics components or sensors. They are foreseen as a potential replacement or complement of Li-ion micro-batteries to enhance the total performance of the whole power source system. The thesis work is mainly focused on adapted materials and technologies for enabling micro-supercapacitors realization. Two types of on-chip micro-supercapacitors with planar interdigitated electrodes configuration were developed: one prepared from Electrophoretic deposition (EPD) and its combination of different carbon materials and different types of electrolytes, the other from patterned titanium or silicon carbide derived carbon film (TiC-CDC or SiC-CDC) on Si chip with different microfabrication techniques. Onion like carbon-based micro-supercapacitor by EPD shows high power delivery (scan rate up to 100V/s) in organic electrolyte, and high temperature range (-50 °C - 80 °C) in a eutectic mixture of ionic liquids. Different techniques for patterning carbide films have been developed to fabricate a CDC based micro- supercapacitor: reactive ion etching (RIE) or focused ion beam (FIB). TiC-CDC film based micro-supercapacitors show promising preliminary results. The developed technologies pave the way to a full and effective integration of micro-size energy storage devices on-chip
Xiao, Xiaoling, and S3060677@student rmit edu au. "Characterization of nano-structured coatings containing aluminium, aluminium-nitride and carbon." RMIT University. Applied Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081217.100453.
Повний текст джерелаMarzorati, S. "PT-FREE NANO- AND MICRO-STRUCTURED CARBONS FOR ELECTROCHEMICAL OXYGEN REDUCTION REACTION." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/332529.
Повний текст джерелаEvanoff, Kara. "Highly structured nano-composite anodes for secondary lithium ion batteries." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53388.
Повний текст джерелаAlshammari, Basheer. "Processing, structure and properties of poly(ethyleneterephthalate)/carbon micro- and nano-composites." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/processing-structure-and-properties-of-poly-ethyleneterephthalatecarbon-micro-and-nanocomposites(0397f989-3be6-4012-a18b-8b91660bd330).html.
Повний текст джерелаHansson, Anders. "Electronic Structure and Transport Properties of Carbon Based Materials." Doctoral thesis, Linköpings universitet, Beräkningsfysik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7544.
Повний текст джерелаBajpai, Vardhan. "SYNTHESES, CHARACTERIZATION AND APPLICATIONS OF MICRO-/NANO-STRUCTURED CONDUCTING POLYMERS AND CARBON NANOTUBES." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1131983430.
Повний текст джерелаLiu, Jing. "Carbon nanotube/polymer composites and novel micro- and nano-structured electrospun polymer materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22673.
Повний текст джерелаCommittee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.
Liu, Yuefeng. "Silicon carbide and nano-carbons containing cobalt catalysts for the Fisher-Tropsch synthesis." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAF024/document.
Повний текст джерелаThe Fischer-Tropsch synthesis (FTS) is a key technology to transform the synthesis gas (2H2 + CO) into liquid hydrocarbons as the basic chemical feedstock. It can be found that the cobalt active sites supported on the materials with high thermal conductivity, opened structure is necessary to accelerate FTS synthesis process in the development of industry catalysts.In this work, a new hierarchical support consisting of α-Al2O3, which is homogeneously covered by a layer of carbon nanotubes, is successfully prepared to support cobalt catalyst. The supported cobalt catalysts show extremely high selectivity towards liquid hydrocarbons along with the better catalytic activity. The FTS performance obtained on this support can be further improved by coating a thin layer of TiO2 on the CNTs surface which significantly improve the cobalt dispersion and in turn,the FTS activity.The TiO2 is also successfully introduced into the matrix of β-SiC during the synthesis process which strongly interacts with cobalt active sites, leading to high dispersion of cobalt, accounting for the better activity and stability in FTS reaction. In the mean time, a highly activity Fischer-Tropsch catalyst based on single crystalline titanium dioxide coated high porosity β-SiC was also developed. The FT specific rate of 1.2 gC5+·gcat -1·h-1 and a C5+ selectivity of 86 % are obtained,which are among the highest FT performance reported up to now on cobalt noble-free catalyst
Bousige, Colin. "Structure et dynamique de systèmes unidimensionnels modèles : les nano-peapods de carbone." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00771820.
Повний текст джерелаYost, Alan. "Effects of Nano-structure Enhanced Cathodes on Power Production in Microbial Fuel Cells." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1325193135.
Повний текст джерелаZhai, Yun. "Studies on Structure and Property of Polymer-based Nano-composite Materials." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1680.
Повний текст джерелаAllouche, Hatem. "Dépôt chimique en phase vapeur de carbone sur substrats nano-filamentaires (nanotubes de carbone)." Toulouse 3, 2002. http://www.theses.fr/2002TOU30229.
Повний текст джерелаMohammed, Khaled. "Preparation and characterisation of some nano-structured catalytic materials for low-temperature oxidation of carbon monoxide." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/367130/.
Повний текст джерелаFigarol, Agathe. "Toxicité in vitro et propriétés physico-chimiques de nanotubes de carbone." Thesis, Saint-Etienne, EMSE, 2014. http://www.theses.fr/2014EMSE0764/document.
Повний текст джерелаDue to their exceptional properties, carbon nanotubes (CNT) have aroused a huge interest among in industrial fields such as microelectronics, material science and nanomedicine. Nevertheless, the health impacts of this nanomaterial still remain not well understood. The first toxicological studies pointed out that there is no unique response regarding the healthimpact of the CNT, but different toxicological profiles according to their various physicochemical properties. A safer by design approach is thus proposed to identify the parameters decreasing from their production the CNT biological impacts. In this context, this work aimed at studying the impact on the in vitro response from a macrophage cell line (RAW 264.7) of two post-Production treatments: acid functionalization and high temperature annealing.Surface acid groups from functionalized CNT enhanced the pro-Inflammatory response although the cytotoxicity remained stable. On the other hand, acid functionalization, through the elimination of metallic impurities, significantly decreased the oxidative stress. Annealed CNT increased the pro-Inflammatory response compared to the pristine CNT. It thus confirmed the sensitivity of this response for the changes in surface chemistry. However, the high temperature annealing did not influence the oxidative stress, despite of the CNT purification. It suggested that structural defects are also of importance for this response. Besides, the acid functionalization of nano-Graphite and carbon black displayed trends in the macrophage response similar to the acid functionalization of CNT. The comparison of these three carbon-Based nanomaterials seemed to conform to the fibre and platelets paradigm. Eventually, exploratory studies have also been conducted on the interferences between CNT and the toxicity assays, and on the oxidative stress
Liu, Chang. "Development of Nanocomposites Based Sensors Using Molecular/Polymer/Nano-Additive Routes." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1557241614006627.
Повний текст джерелаFan, Benhui. "Propriétés diélectriques des composites à matrice PVDF comportant des renforts hybrides nano/micro-échelles (nanotubes de carbone et BaTiO₃)." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLC005/document.
Повний текст джерелаThe dispersibility of carbon nanotube (CNT) in polyvinylidene fluoride (PVDF) is always a big challenge for the high dielectric property. Barium titanate (BT)-CNT hybrids with the special structure are proved to be effective for improving the dispersion of CNT in the polymer matrix and reduce the percolation threshold of the composite. This thesis aims to achieve high dielectric performance of composites via designing fillers with the favorable structure as well as comprehensively study the interaction between CNT and semi-crystalline polymer matrix.In chapter 1, we provide a general introduction about dielectric material's background knowledge. Meanwhile the development including recent breakthroughs and their applications for the dielectric field are also provided in this chapter.In chapter 2, we prepare two hybrids with different structures. The first hybrids are prepared by chemical vapor deposition (CVD) method. It is with the structure of BT as a core and CNTs growing outsides (H-CNT-BT). The second hybrids are prepared by hydrothermal reaction where BT particles coats outside CNT (H-BT-CNT). Meanwhile, we fabricate hybrids reinforced PVDF matrix composites by solution casting plus extrusion-injection way. Additionally, methods for characterization involving morphology, thermal and dielectric properties as well as crystallization are also introduced in this chapter.In chapter 3, the dielectric behaviors of H-CNT-BT/PVDF are studied concretely. A dramatic increment on dielectric permittivity is observed after the thermal treatment. This change may result from the reformation of CNT's conductive network and the behavior of PVDF's re-crystallization. By modeling work and experimental characterization, the shrinkage of the neighboring CNT's distance in PVDF's amorphous layers and the induced β polymorph at the CNT-PVDF interface may cause the significant increment in dielectric permittivity after the thermal treatment.In chapter 4, the CNT's dispersibility in PVDF matrix composites is studied by designing different structures. Firstly, a comparison between calculated and experimental percolation threshold of H-CNT-BT/PVDF is conducted for studying the morphology parameters of H-CNT-BT. Afterwards, two comparisons are conducted: one is between H-CNT-BT/PVDF and CNT/PVDF. The processing factors for the CNT's dispersibility are discussed via measuring the different layer's AC conductivity. The other is among three hybrids reinforced PVDF composites. The hybrids structure's effect the CNT's dispersibility is discussed via comparing the dielectric property of the composites with the same volume fraction of CNT and BT but different structures.In chapter 5, a general conclusion is formed according to the works and the perspective is provided for the improvement of the future work
Zhang, Yan. "SURFACE AND STRUCTURAL MODIFICATION OF CARBON ELECTRODES FOR ELECTROANALYSIS AND ELECTROCHEMICAL CONVERSION." UKnowledge, 2018. https://uknowledge.uky.edu/chemistry_etds/96.
Повний текст джерелаAhn, Hee Seok. "Heat transfer enhancement in single-phase forced convection with blockages and in two-phase pool boiling with nano-structured surfaces." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5869.
Повний текст джерелаEberhardt, Oliver, and Thomas Wallmersperger. "Analysis of the mechanical behavior of single wall carbon nanotubes by a modified molecular structural mechanics model incorporating an advanced chemical force field." SPIE, 2018. https://tud.qucosa.de/id/qucosa%3A35173.
Повний текст джерелаZhang, Jie. "Contribution aux développements des technologies de compression polymères chargés pour la réalisation d'inserts métalliques micro-structurés." Thesis, Besançon, 2013. http://www.theses.fr/2013BESA2044/document.
Повний текст джерелаThe Ph.D subject concerns the study of two micro-replication processes by hotembossing and roll to roll processes for thermoplastic polymers and loaded polymers withpowders or carbon nanotubes. The micro-replication processes, realized in sequential orcontinuous ways, use some different elaborated loaded feedstocks in order to obtainstructural components or micro-component with high aspect ratio and mechanical orthermo-physical properties.A chain combining hot embossing and roll embossing and powder metallurgy have beendeveloped in our lab and investigated. The different micro mould die cavities have beenrealized with different micro-manufacturing process, elastomeric mould has been obtainedby casting process. Finally, a metallic structured die cavity has been obtained by combininghot embossing and debinding and sintering stages. The second topic is the comparison ofmetallic die cavity mould obtained by roll embossing or rolls embossing. Two demonstratorshave been developed during the preparation of this Ph.D period: first a metallic micro-fluidicsystem with micro-structuration with diameter of 1 mm for the reservoir and 200 microns by200 microns for the channel have been realized and characterized by different methods.Secondly, some functional micro-component has been obtained with carbon nanotube andsome specific properties in terms of mechanic and thermo-physical properties have beencharacterized
Soliveres, Sébastien. "Caractérisation de la conduction et du bruit basse fréquence dans des macro et nano structures à base de nanotubes de carbone." Montpellier 2, 2006. http://www.theses.fr/2006MON20093.
Повний текст джерелаQi, Ling. "Design of hybrid organic-inorganic nanostructures via electroastic assembly in solutions and at interfaces : structure, organization and functionalities." Paris 6, 2009. http://www.theses.fr/2009PA066213.
Повний текст джерелаMaruzhenko, Oleksii. "Structure, thermal and electrical properties of nanocomposites with hybrid fillers." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI131.
Повний текст джерелаThe thesis determines the principles of the conductive phase structure formation in polymer composites containing conductive fillers, which will be different types of carbon fillers. The processes of segregated structure formation in which the particles of the filler are localized on the surfaces of polymer grains is studied. It is shown that the value of the percolation threshold φc for the segregated system is one order lower than in the composite with a random distribution of the filler 2.95 vol.% and 24.8 vol.%, respectively. The hybrid filler shows percolation threshold, much lower than the value calculated using the mixing rule. Experimental results of thermal conductivity for systems filled with anthracite, graphene and hybrid filler Gr/A do not reveal percolation behaviour and can be well described by the Lichtenecker model. It is shown that λf for segregated systems is 4.4 times higher than for a composite with a random distribution of filler particles. It is shown that in segregated systems the shielding parameters are significantly increased due to the absorption caused by the internal reflection on the conductive walls of the filler framework. Carbon fillers create the most effective basis that ensures a high absorption rate of EMI at low concentrations. It was found that the greatest shielding effect in the interaction of a composite with electromagnetic radiation was observed for the hybrid filler GNP/CNT (graphite nanoplatelets/carbon nanotubes). The synergistic effect is explained not by their higher electrical conductivity, but by the better interaction of the EMI with the developed hybrid framework of the filler, which causes increased absorption of the EMI. Systems with a segregated structure based on elastomer (ground rubber) with a polymer-adhesive and hybrid electroconductive nano-fillers exhibit a significant piezoresistive effect. The cyclic studies of electric response, depending on the applied external load, showed a linear relationship between composite deformation and current changes through the sample and demonstrate stable long-term stability. The study of the piezoresistive effect in a wide temperature range (-40 ÷ +50°C) showed the stability of the main characteristics and the possibility of exploiting the composite in a wide temperature range
Lin, Jing-Pei, and 林璟培. "Synthesis of Carbon Nano-Structures in Alcohol Flames." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/59134296275718302178.
Повний текст джерела崑山科技大學
機械工程研究所
102
This study aimed at investigating the synthesis of carbon nanostructures in butanol/aqueous ammonia and ethanol/aqueous ammonia flames using an alcohol lamp burner. Pure n-butanol (purity 99.8%), pure ethanol (purity 95%), n-butanol/aqueous ammonia (25% NH3) blends, and ethanol/aqueous ammonia blends were used in this study. Aqueous ammonia was mixed with various proportions (10, 20, and 30%) in butanol or ethanol for use as liquid fuels. A nascent nickel mesh was employed as the catalytic metal substrate to collect deposit materials. The deposition time was two minutes. Additionally, scanning electron microscope (FE-SEM) and high resolution field emission scanning transmission electron microscopy (HR-TEM) were used to observe and analyze the microstructure and morphology of generated carbon nonostructures under different experimental conditions. First, flame appearances were observed. With increasing the content of aqueous ammonia, it was found that the blue part generated at the yellow flame base became more apparent for the n-butanol/aqueous ammonia flames, and that the flame color changed gradually from yellow to brown for the ethanol/aqueous ammonia blends. From the results of SEM analysis, it was observed that, for pure n-butanol, carbon nanotubes (CNTs) were synthesized at the axial positions z = 6, 8, 10 and 12 mm above the wick where the temperature was in the range of about 700 – 950℃. As n-butanol concentration was 90% in the n-butanol/aqueous ammonia blends, carbon nano-onions (CNOs) were produced at the heights z = 10, 12, 14, 16, 18, 20 and 22 mm where the temperature was between 750 and 950℃. For the n-butanol concentration of 80%, CNTs were fabricateded at a lower axial position z = 4 mm, where the temperature was identified to lie between 700 and 740℃; however, at higher heights z = 12, 14, 16, 18, 20 and 22 mm, CNOs were synthesized, where the temperature was located in the range of 825 – 1030℃. As the n-butanol concentration was 70%, CNTs were found at lower hights z = 4 and 6 mm where the temperature range was within 620 – 750℃; however, at higher heights z = 12, 14, 16, 18 and 20 mm with a temperature range of about 800 – 1040℃, CNOs were observed. For pure ethanol (100% ethanol), at the height z = 4 and 6 mm (where the temperature range was about 520 – 620 ℃), CNTs were generated. For the ethanol concentration of 90%, at the heights z = 4, 6 and 8 mm (where the temperature was ranged approximately from 750 to 850 ℃), CNTs were synthesized. Under the operating conditions of ethanol concentration being 80%, at the heights z = 4, 6 and 8 mm (where a temperature range of about 690 – 780 ℃ was generated), CNTs were produced. As ethanol concentration was 70%, at the heights z = 4 and 6 mm (where the temperature range was about 655 – 770 ℃, few CNTs were fabricated; whereas, at the heights z = 8, 10, 12, 14 and 16 mm (where the temperature range of about 840 – 1030 ℃ was produced), more CNTs were synthesized. With increasing axial position from z = 8 mm progressively, a larger amount of CNTs were synthesized at z = 8 mm, achieved the maximum yield at z = 10 mm afterwards, and then the formation of CNTs decreased gradually. Based on the results of HR-TEM analysis, it is noteworthy that few layer graphenes were also observed (which were not found easily in SEM analysis) when the concentration of n-butanol was 100% and the sampling positions were located at z = 10 and 12 mm or when the concentration of n-butanol was 90% and the sampling positions were placed at z = 14 and 18 mm. Moreover, graphenes were not observed in pure ethanol and ethanol/aqueous ammonia flames.
Huang, Fang-Chi, and 黃芳琪. "Synthesis of Carbon Nano-Structures in Partially-Premixed Jet Flames." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/63879205382691051986.
Повний текст джерела崑山科技大學
機械工程研究所
98
Combustion synthesis of carbon nano-structures using ethylene-air partially-premixed jet flames and a catalytic Ni substrate was investigated. In the experiments, the injection velocity of fuel-air mixture was kept constant. The influences of sampling position, gas temperature and concentration distributions on the synthesis of carbon nanostructures were examined. The results showed that the increase of fuel concentration leads to an increase of flame height and a wider range of yellow flame (sooty zone). Additionally, a quantity of carbon nano-onions was synthesized at Z = 40 ~ 60 mm for ethylene concentrations of 15.1%, 15.7% and 16.3%; however, only little carbon nanostructure was synthesized at Z = 70 mm because the temperature was too high. It has been verified that the key parameters influencing the formation and yield of CNOs were carbon sources (mainly both the CO and C2H2 concentrations), and heat source (suitable temperature range around 970 ~ 1300 ℃). High-resolution transmission electron microscopy (HR-TEM) and scanning electron microscopy (SEM) images confirmed the presence of spherical carbon nano-onions with diameters ranging from 20 to 40 nm.
Feng-RennJuang and 莊豐任. "Studies of Various Novel Nano Structures High Performance Carbon Monoxide Gas Sensors." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/23015199322754984741.
Повний текст джерелаChen, Kuan-Ming, and 陳冠名. "Flame Synthesis of Carbon Nano-Structures in Acoustically Modulated Methane Diffusion Flames." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16450254767356439120.
Повний текст джерела崑山科技大學
機械工程研究所
100
Methane jet diffusion flames modulated by acoustically excitation in an atmospheric environment were used to synthesize carbon nano- structures. A catalytic nickel substrate was employed to collect the deposit materials at sampling positions z = 10 mm above the burner exit. The influence of acoustic amplitude and frequency on flame synthesis of carbon nanotubes (CNTs) and nano-onions (CNOs) was investigated. The formation of CNOs was significantly enhanced by acoustic excitation at the frequencies near either the natural flickering frequency (ƒN = 20 Hz) or the acoustically resonant frequency (ƒR = 90 Hz). At these characteristic (resonant) frequencies, flow mixing was markedly enhanced by acoustic excitation, and the flame structure with a bright slender core flame was generated, which provided a favorable flame environment, i.e. a high radical concentration (carbon source) and a temperature range (heat source), for the formation of CNOs. The power of the acoustic exciter, P, (related to the amplitude of the excitation) was adjustable. At P = 5W, the production rate of CNOs was high at 20 Hz (near the natural flickering frequency) for a sampling position z = 10 mm above the burner exit where the gas temperature was about 660℃. Additionally, a quantity of CNTs could be obtained at 70 ~ 95 Hz, near the acoustically resonant frequency, where the gas temperature was between 660~870℃. However, almost no CNOs and CNTs were synthesized for the other frequencies due to low temperature or lack of carbon sources. At higher power of the acoustic exciter, P = 10 and 15W, a mass of CNTs could be fabricated at 70 ~ 85 Hz, close to the acoustically resonant frequency, where the gas temperature was in the range of 660~810℃. On the contrary, nearly no carbon nano-material was observed for the other frequencies due to low temperature or lack of carbon source. Finally, Raman spectra showed that the intensity ratios of the D- and G-bands for all the carbon nano-structures synthesized herein were lower than one (i.e. ID/IG < 1). This reveals that the CNTs and CNOs had a high degree of graphitization. The enhanced synthesis of CNOs was caused by strong mixing of the fuel and oxidizer due to the acoustic excitation at the resonant frequencies.
Nanda, Abhishek. "Finite Element Modelling and Analysis of Carbon Nanotobe Based Nano Composite Structures." Thesis, 2015. http://ethesis.nitrkl.ac.in/7735/1/2015_FINITE_ELEMENT_Nanda.pdf.
Повний текст джерелаYang, Zong-Yun, and 楊宗運. "Synthesis of Carbon Nano-Structures Enhanced by Acoustic Modulation in Jet Diffusion Flames." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48102564124562432176.
Повний текст джерела崑山科技大學
機械工程研究所
102
Methane jet diffusion flames modulated by acoustically excitation in an atmospheric environment were used to synthesize carbon nano- structures. A catalytic nickel substrate was employed to collect the deposit materials at sampling positions z = 10 and 15 mm above the burner exit. The influence of acoustic amplitude and frequency on flame synthesis of carbon nanotubes (CNTs) and nano-onions (CNOs) was investigated. The formation of CNOs was significantly enhanced by acoustic excitation at the frequency near the natural flickering frequency (ƒN = 20 Hz), and the fabrication of CNTs was greatly enhanced by acoustic excitation at the acoustically resonant frequency (ƒR = 90 Hz). At these characteristic (resonant) frequencies, flow mixing was markedly enhanced by acoustic excitation, and the flame structure with a bright slender core flame was generated, which provided a favorable flame environment, i.e. a high radical concentration (carbon source) and a temperature range (heat source), for the formation of CNOs or CNTs. The power of the acoustic exciter, P, related to the amplitude of the excitation, was adjustable. At P = 5, 10, and 15 W, the production rate of CNOs was high at 20 Hz (near the natural flickering frequency) for a sampling position z = 10 mm above the burner exit where the gas temperature was about 450~550℃. Additionally, a quantity of CNTs could be obtained at 80 ~ 95 Hz, near the acoustically resonant frequency, where the gas temperature was between 700 and 740℃. However, almost no CNOs and CNTs were synthesized for the other frequencies due to low temperature or lack of carbon sources. The enhanced synthesis of CNOs was caused by strong mixing of the fuel and oxidizer due to the acoustic excitation at the resonant frequencies. For fixed acoustic amplitude 10W and fuel velocity V = 20 cm/s,the results of concentration field analysis showed that at low frequencies and low C2H2 concentrations, a lot of carbon nano-onions were synthesized; but at high frequencies and high C2H2 concentrations, carbon nanotubes were fabricated.
KuoWen-Chih and 郭文智. "A Study on Carbon Nano-Structures in Inverse Diffusion Flames of Mixed Fuels." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/96729726020184841160.
Повний текст джерела崑山科技大學
機械工程研究所
95
The formation and growth of carbon nano-structures including carbon nanotubes (CNTs) and carbon nanocapsules in inverse co-flowing diffusion flames of mixed fuel were experimentally studied. The influences of volumetric methane concentrations in ethylene/nitrogen mixture from the outer jet, sampling position and substrate (uncoated or coated with Ni(NO3)2-36.4% by weight) upon the yield of carbon nano-structures were particularly emphasized. The flame appearance, flame structure, and flame stability under the influences of inner/outer velocity ratios, volumetric oxygen concentrations in nitrogen of the inner jet and methane concentrations in ethylene/nitrogen mixture of the outer jet were firstly studied using image processing techniques. The results showed that increasing the injection velocity of oxygen/nitrogen mixture, the sooty zone becomes narrower, leading to an increase in the critical methane concentration require for the occurrence of yellow flame (sooty zone). However, raising oxygen concentration of inner jet or fuel (methane or ethylene) concentration of outer jet resulted in an increase in flame height and a wider range of sooty zone, and in turn a decrease in the critical fuel concentration required for the occurrence of yellow flame. Thereafter, we employed a sampling Ni grid as the catalytic metal substrate for the carbon nano-structures growth. The sampler was mounted on a two-dimensional micro-positioner with the plane normal to the burner axis. The sampling time of the substrate inside the flame was kept at 120 sec. The SEM and TEM images showed that carbon nano-structures depositted on the substrates were mainly CNTs and carbon nanocapsule. Curved and entangled tubular multi-walled CNTs (MWCNTs) were harvested, which had both typical straight tubular and bamboo-like structures. Besides curved CNTs, carbon nanocapsules were also synthesized, inside which metal particles were encapsulated. It is of interest to note that only MWCNTs were generated when the mixture of 5% methane/5% ethylene/90% nitrogen and the mixture of 10% methane/5% ethylene/85% nitrogen were separately used as the fuel. Both the growth range and yield of CNTs of the former are smaller than those of the latter. However, carbon nanocapsules synthesized on Ni(NO3)2-coated substrates were found when the methane concentration of outer fuel jet was equal to 30% (i.e. 30% methane/5% ethylene/65% nitrogen). Furthermore, for the same sampling approach, the sampling positions on or near the flame front had a greater carbon nano-structures harvest than those far from the flame front. Using Ni(NO3)2-coated substrates had advantages over uncoated Ni(NO3)2 substrates, which can increase the range, quantity and length of carbon nano-structures.