Дисертації з теми "Nano structure materials"
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Duplock, 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 джерелаBai, Feiming. "Structure-Property Relationships of Multifeorric Materials: A Nano Perspective." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28055.
Повний текст джерелаPh. D.
Alswieleh, Abdullah. "Micro- and nano-structure of polymers and molecular materials." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7164/.
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 джерелаHua, Weijie. "Structure and spectroscopy of bio- and nano-materials from first-principles simulations." Doctoral thesis, KTH, Teoretisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31944.
Повний текст джерелаQC 20110404
Hansson, 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 джерелаBigatti, Marco. "Quantitative studies of the structure and chemistry of materials at the nano- and atomic-scale." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6393/.
Повний текст джерелаMiller, Derek. "Advancing electronic structure characterization of semiconducting oxide nano-heterostructures for gas sensing." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492639729205609.
Повний текст джерелаKocsis, Balázs [Verfasser], and Wolfgang [Akademischer Betreuer] Schmahl. "Structure of nano-crystalline apatite in bone and bone-analogous materials / Balázs Kocsis ; Betreuer: Wolfgang Schmahl." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1236502183/34.
Повний текст джерелаVinogradov, Nikolay. "Controlling Electronic and Geometrical Structure of Honeycomb-Lattice Materials Supported on Metal Substrates : Graphene and Hexagonal Boron Nitride." Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-194089.
Повний текст джерелаZhong, Yuan. "Sub-grain structure in additive manufactured stainless steel 316L." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-144519.
Повний текст джерелаAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.
Sahni, Vasav. "From Nano to Micro to Macro: Importance of Structure and Architecture in Spider Silk Adhesives." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342412634.
Повний текст джерелаShehata, Asmaa. "Engineering Properties, Micro- and Nano-Structure of Bentonite-Sand Barrier Materials in Aggressive Environments of Deep Geological Repository for Nuclear Wastes." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32499.
Повний текст джерелаVillar, Gabriel. "Aqueous droplet networks for functional tissue-like materials." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:602f9161-368c-48c0-9619-7974f743f2f2.
Повний текст джерелаMa, Yanhang. "Structural study of nano-structured materials: electron crystallography approaches." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129233.
Повний текст джерелаEder, Katja Daniela. "Surfaces and interfaces in nano-scale and nano-structured materials." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17217.
Повний текст джерелаMohamed, Rozita. "Preparation of nano-structured macro-porous materials." Thesis, University of Newcastle upon Tyne, 2011. http://hdl.handle.net/10443/1317.
Повний текст джерелаTan, Yue. "Fabrication of nano-structured palladium membranes." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40791.
Повний текст джерелаLe palladium, étant imperméable à tous les gaz à l’exception de l'hydrogène, a été largement étudié pour l'extraction d'hydrogène dans les dernières années. La surface spécifique de la membrane est un facteur important qui affecte le taux de perméabilité d'hydrogène. Un grand défi pour la communauté scientifique est d’obtenir une membrane en palladium avec une surface spécifique élevée. Dans cette étude, une nouvelle technique utilisant une matrice ordonnée a été employée pour préparer des membranes de palladium nano-structurées avec une surface de contact avec l’hydrogène considérablement accrue.Tout d’abord, l'oxyde d'aluminium anodique (OAA) a été fabriqué en anodisant une couche d’aluminium électro-déposée et un papier d'aluminium commercial. Puis, la matrice d'OAA a été remplie de palladium utilisant la technique électrochimique et la technique par pulvérisation. De divers facteurs affectant la préparation de la membrane de palladium ont été analysés et optimisés. Les expériences préliminaires de la perméabilité d’hydrogène ont clairement prouvé que de telles membranes de palladium sont un candidat prometteur pour l'application de la séparation d'hydrogène.
Betancur, Lopera Rafael. "Photon control in nano-structured organic photovoltaic materials." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/128967.
Повний текст джерелаLa tecnología fotovoltaica orgánica (OPV) ha surgido como una solución potencial rentable para producir energía eléctrica. Los bajos costos de manufactura previstos combinados con propiedades como semi-transparencia o flexibilidad mecánica le dan a los dispositivos OPV un gran potencial de ser aplicados industrialmente. Sin embargo, la implementación comercial de esta tecnología se enfrenta al reto de incrementar la relativamente baja eficiencia de los dispositivos OPV del estado del arte. Esta tesis presenta una aproximación óptica para aumentar la eficiencia de los dispositivos OPV mediante un control efectivo de los fotones de la radiación solar. Tal control es posible debido a la interacción coherente entre la luz y la estructura de multi-capas que constituye el dispositivo OPV. Consecuentemente, en esta tesis se estudia la dependencia de la distribución del campo óptico dentro de la celda solar con las propiedades ópticas de las diferentes capas. Entre esas propiedades se incluyen el índice de refracción , el coeficiente de extinción y espesor de cada una de las capas. Este estudio óptico ha permitido predecir estructuras óptimas para los dispositivos OPV. La primera implementación del control de fotones fue hecha al cambiar los espesores relativos de las diferentes capas en el dispositivo. Una combinación óptima fue encontrada y confirmada experimentalmente. Una reducción significativa de la energía perdida por reflexión especular fue demostrada y como consecuencia, la recolección de fotones fue mejorada lo cual condujo a la concordancia entre las eficiencias cuánticas externa e internas en un amplio rango de longitudes de onda. Una segunda estrategia de control de fotones para mejorar el desempeño de los dispositivos OPV fue implementada tras modificar las propiedades ópticas de las capas en el dispositivo distintas a la capa activa. Tanto como fueron cambiados en capas específicas tras considerar nuevos materiales. Tres casos diferentes fueron considerados: en el primer caso, una capa de BCP fue usada para reemplazar el calcio como capa transportadora de electrones. La absorción parásita inducida por el elvevado coeficiente de extinción de la capa de calcio fue reducida casi hasta cero tras reemplazar esta capa con una de BCP, un material cuyo coeficiente de absorción es prácticamente cero para un amplio rango de longitudes de onda. Se demostró un aumento en el desempeño de los dispositivos de hasta el 19%. En el segundo ejemplo, una capa ultra-delgada de óxido de níquel fue usada para reemplazar la comúnmente empelada capa de PEDOT como capa transportadora de huecos. Estas capas de óxido de níquel permitieron una mejor distribución y recolección de fotones en la capa foto-activa. En el último caso, un electrodo semi-transparente hecho de cobre/níquel fue usado para reemplazar un electrodo de ITO. Este nuevo electrodo metálico en combinación con el electrodo de aluminio posterior del dispositivo permitió la formación de una cavidad óptica la cual resultó en una mayor localización del campo en la capa activa. Finalmente, varios de los conceptos considerados anteriormente para localizar efectivamente el campo en la capa activa fueron usados en combinación con una estructura fotónica integrada en la estructura para obtener un dispositivo OPV semitransparente ópticamente optimizado. Concretamente, un cristal fotónico unodimensional no-periódico fue diseñado y añadido al dispositivo OPV semi-trasparente con la intención de recolectar fotones UV e IR y al tiempo manteniendo una alta transmisión de los fotones visibles. Una mejora en el desempeño de los dispositivos superior al 56% fue obtenida preservando la luminosidad del dispositivo alrededor del 30%. Una propiedad adicional aportada por la integración de tales cristales fotónicos fue la posibilidad de modular el color transmitido por el dispositivo lo cual fue también demostrado. En síntesis, en esta tesis se demostró experimental y teóricamente que la óptica juega un papel relevante para aumentar la eficiencia de los dispositivos OPV. Los métodos presentados son perfectamente compatibles con la aproximación que se realiza desde la perspectiva de la ciencia de los materiales al objetivo final de obtener una tecnología OPV competitiva.
Petkova, Petya Stoyanova. "Surface nano-structured materials to control bacterial contamination." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/398122.
Повний текст джерелаLa propagación de bacterias e infecciones, inicialmente limitada a infecciones adquiridas en el hospital, se ha extendido al resto de la sociedad causando enfermedades muy graves y más difíciles de tratar. Además, muchas de estas enfermedades son provocadas por bacterias que se han hecho resistentes a los antibióticos convencionales. Por lo tanto, limitar la capacidad de estas bacterias para desarrollar resistencia puede potencialmente reducir la alta incidencia de estas infecciones y evitar miles de muertes cada año. Las partículas de escala nanométrica son unas candidatas prometedoras para combatir las bacterias, ya que su mecanismo de acción las hace disminuir las probabilidades en el desarrollo de resistencia. Las nanopartículas (NPs) se pueden incorporar en matrices poliméricas para diseñar una amplia variedad de materiales nanocompuestos. Estas nanoestructuras consisten en NPs orgánicas/inorgánicas e inorgánicas representando una nueva clase de materiales con una amplia gama de aplicaciones. Esta tesis trata sobre el desarrollo de materiales antibacterianos con estructura nanométrica dirigidos a prevenir la propagación de bacterias. Para lograr esto, dos herramientas fisicoquímicas y biotecnológicas versátiles tales como sonoquímica y biocatálisis, se combinaron de manera innovadora. La irradiación por ultrasonido se ha utilizado para la generación de nanoestructuras diversas y su combinación con biocatalizadores (enzimas) abre nuevas perspectivas en el tratamiento de materiales, aquí ilustrados por la producción de textiles médicos recubiertos con NPs, membranas de tratamiento de agua y apósitos para heridas crónicas. La primera parte de la tesis tiene como objetivo el desarrollo de textiles médicos antibacterianos para prevenir la transmisión y proliferación de bacterias utilizando dos estrategias "de un solo paso" para el recubrimiento antibacteriano de estos textiles con NPs. En el primer enfoque NPs antibacterianas de óxido de zinc (ZnO NPs) y quitosano (CS) fueron depositadas simultáneamente sobre tejido de algodón por irradiación de ultrasonido. Los recubrimientos híbridos de NPs obtenidos demostraron propiedades antibacterianas duraderas después de varios lavados exhaustivos. Por otra parte, la presencia de biopolímeros en las NPs híbridas mejoraba la biocompatibilidad del material en comparación con el recubrimiento de solamente de ZnO NPs. En la segunda parte de la tesis, híbridos antibacterianos hechos de biopolímeros y NPs de plata y matrices de corcho, fueron ensamblados enzimáticamente en un material antimicrobiano para su utilización en la remediación de aguas. Biopolímeros antibacterianos aminofuncionalizados (CS y aminocelulosa) se utilizaron como agentes dopantes para estabilizar las dispersiones coloidales de plata (Ag NPs). Además, estas partículas presentan todas las funciones necesarias para su inmovilización covalente en el corcho proporcionando un efecto antibacteriano duradero. Estos biopolímeros aumentaron la eficacia antibacteriana de estos nanocompuestos en condiciones que simulan una situación real en humedales construidos. En la tercera parte de la tesis, se desarrolló un hidrogel nanocompuesto bioactivo para el tratamiento de heridas crónicas. Nanoesferas de galato de epigalocatequina (EGCG NSs) fueron sintetizadas a través de sonoquimica y se incorporaron y simultáneamente reticularon enzimáticamente en un hidrogel de quitosano tiolado. El potencial del material generado para el tratamiento de heridas crónicas fue evaluado por sus propiedades antibacterianas y su efecto inhibidor sobre biomarcadores producidos en heridas crónicas infectadas (mieloperoxidasa y colagenasa). También se consiguió la liberación sostenida de EGCG NSs por parte de la matriz generada, que junto con su buena biocompatibilidad, demostraba su potencial para el tratamiento de heridas crónicas.
Chen, Guodong. "Thermal and Mechanical Behavior of Nano-structured Materials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1326398846.
Повний текст джерелаDe, Leonardis Piero. "Preparation and characterization techniques for nano-structured materials." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/preparation-and-characterization-techniques-for-nanostructured-materials(5b5468e8-1fe7-4baa-b073-9ce51f2b280a).html.
Повний текст джерелаThomas, Gareth James. "Advanced materials for plasma facing components in fusion devices." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:f8ba1ae1-f303-4c32-877e-dca421a3cb5c.
Повний текст джерелаZhang, Li 1973. "Shockwave consolidation of nano silver powder into bulk nano structured silver." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100238.
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 джерелаSafdar, Amna. "Nano-structures and materials for wafer-scale solar cells." Thesis, University of York, 2018. http://etheses.whiterose.ac.uk/20561/.
Повний текст джерелаCox, 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 джерелаTuling, Russell J. "Optical field response from structured nano- and mesocomposites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ44305.pdf.
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).
PIRANI, FEDERICA. "Bio-oriented Micro- and Nano- Structures Based on Stimuli-responsive Polymers." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2706874.
Повний текст джерелаSchaarschmidt, Martin. "Theory of light propagation in nano-structured materials and semiconductors." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980074541.
Повний текст джерелаChen, Zhihui. "Light manipulation in micro and nano photonic materials and structures." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94081.
Повний текст джерелаQC 20120507
Ye, Fei. "Chemically Synthesized Nano-Structured Materials for Biomedical and Photonic Applications." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96261.
Повний текст джерелаQC 20120605
Purwaningsih, Lindarti [Verfasser]. "Fabrication of nano-structured materials and their applications / Lindarti Purwaningsih." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018222820/34.
Повний текст джерелаKnowles, John Philip. "The preparation, characterisation and application of nano-structured mesoporous materials." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437124.
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
Beets, Nathan James. "Computational Studies of the Mechanical Response of Nano-Structured Materials." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/98468.
Повний текст джерелаDoctor of Philosophy
Crystalline metals can be synthesized to have a sponge-like structure of interconnected ligaments and pores which can drastically change the way that the material chemically interacts with its environment, such as how readily it can absorb oxygen and hydrogen ions. This makes it attractive as a catalyst material for speeding up or altering chemical reactions. The change in structure can also drastically change how the material responds when deformed by pressing, pulling, tearing or shearing, which are important phenomena to understand when engineering new technology. High surface or interface area to volume ratios can cause a massive surface-governed capillary force (the same force that causes droplets of water to bead up on rain coat) and lead to a higher pressure within the material. The effect that both structure and capillary forces have on the way these materials react when deformed has not been established in the context of capillary force theory or crystalline material plasticity theory. For this reason, we investigate these materials using simulation methods at the atomic level, which can give accurate and detailed data on the stress and forces felt atom-by-atom in a material, as well as defects in the material, such as dislocations and vacancies, which are the primary mechanisms that cause the crystal lattice to permanently deform and ultimately break. A series of parameters are varied for multiple model systems to understand the effects of various scenarios, and the understanding provided by these tests is presented.
El-Zahab, Bilal Mohamad Issam. "Multi-Enzyme Biocatalysis Using Nano-Structured Materials for Bioprocessing Applications." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1239641945.
Повний текст джерелаTrinh, Duc Thien. "Linear electrooptic microscopy : applications to micro and nano-structured materials." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0012/document.
Повний текст джерелаComplementing Second-Harmonic Generation (SHG) microscopy, a new home-made nonlinear microscope named Pockels Linear Electro-Optical Microscopy (PLEOM) based on the linear electrooptic (Pockels) effect, has been developed and used to map the second-order susceptibility Chi(2) of non-centrosymmetric materials with high sensitivity due to a stabilized interferometric homodyne detection scheme [1, 2]. This enables PLEOM to detect the electrooptic phase retardation of light resulting from the variation of the refractive index of nonlinear materials down to 10-6 radian and to investigate nonlinear materials at the nano-scale [3] towards applications in imaging of biological samples and tracking of labels therein. With PLEOM, a new imaging method allows to access, besides the aplitude, the no less crucial phase response, which is not readily amenable to classical SHG microscopy. In the frame of this dissertation, we have further extended the range of applications of PLEOM to investigate nonlinear materials and structures from nano- to millimeter-scale.Firstly, we have proposed and demonstrated a new approach towards the full vector determination of the spontaneous polarization of single ferroelectric nano-crystals used as SHG nano-probes. This method allows to remove the ambiguity inherent to earlier polarization-resolved SHG microscopy experiments, and has permitted full determination of the orientation of single domain ferroelectric nano-crystals. The electrooptic phase response obtained in the form of phase images and polarization diagrams yields the full orientation in the laboratory frame of randomly dispersed single nano-crystals, together with their electric polarization dipole. The complete vector determination of the dipole orientation is a prerequisite to important applications including ferroelectric nano-domain orientation, membrane potential imaging and rotation dynamics of single biomolecules, especially by using a new low-cost non-invasive imaging method with a low intensity illumination beam.The ferroelectric domain pattern of periodically poled KTiOPO4 and of a two-dimensional decagonal quasi-periodic LiNbO3 nonlinear crystal was determined by local measurement of their electro-optically induced phase retardation. Owing to the sign reversal of the electrooptic coefficients upon domain inversion, a 180 degree (pi) phase shift is observed across domain barriers between domains with opposed orientations. PLEOM allows to reveal the nonlinear and electrooptic spatially modulated patterns in ferroelectric crystals in a non-destructive manner and to determine their poling period, duty cycle and short-range order as well as to detect local defects in the domain structure, such due to incomplete poling.In addition, we have also proposed and demonstrated a new method, based on the voltage dependence of the electrooptic dephasing, to mimic the membrane potential in cells, working at this stage on nonlinear dye containing phospholipidic membranes, grown in a microfluidic set-up
Qiu, Yongfu. "Controlled growth and characterization of one-dimensional nano-structured materials /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?NSNT%202008%20QIU.
Повний текст джерелаLi, Lan. "Molecular dynamics simulations of the deformation of nano-structured materials." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1324388961&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Повний текст джерелаKhan, Abdullah. "Synthesis and characterization of nano-structured CoSb3 thermoelectric material." Thesis, KTH, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10810.
Повний текст джерелаQC 20100708
Lee, Eun Seong. "Light-exciton coupling in semiconductor micro- and nano-structures." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279986.
Повний текст джерелаYan, Kun. "Size effects on the thermo-mechanical behavior on nano-structures/ materials." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290513.
Повний текст джерелаMehrez, Hatem. "Theoretical study of nano structures and molecular electronic systems." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38237.
Повний текст джерелаIn this thesis we theoretically investigate quantum coherent transport properties of nano structures in the form of molecular electronic systems. Our approach is based on Landauer-Buttiker transport theory. However, the details of the method depend on the interaction complexity.
We have carried out detailed analysis on finite length carbon nanotubes based magnetic tunnel junction using tight binding atomic model and Green's function approach. This device shows clear spin valve effect even when contacted with the same ferro-magnetic material with a long spin scattering length. In addition to this, transport at the atomic level is highly affected by the molecular states resulting in conductance oscillation of finite size arm-chair carbon nanotube as a function of its length.
When short carbon nanotubes are weakly contacted to external leads, they act as quantum dots with strong interaction at the molecular scale. To analyse these systems, we have developed a many-body wave function formalism which include spin degeneracy. This approach clearly shows the strong dependence of the device electronic response on the number of electrons already inside the tube.
Finally, we have carried out ab initio analysis based on Density Functional Theory within Local Density Approximations to investigate the current-voltage (I-V) characteristics of various gold nanowires. Our results demonstrate that transport properties of these systems crucially depend on the electronic properties of the scattering region, the leads, and most importantly the interaction of the scattering region with the leads. For ideal, clean Au contacts, the theoretical results indicate a linear I-V behavior. However, when sulfur impurities exist at the contact junction, nonlinear I-V curves emerge due to a tunnelling barrier established in the presence of the S atom. The most striking observation is that even a single S atom can cause a qualitative change of the I-V curve from linear to nonlinear.
Our theoretical results were compared to experimental data, qualitative and sometimes quantitative understanding of the experiments are obtained.
Yan, Kun, and 閆琨. "Size effects on the thermo-mechanical behavior on nano-structures/ materials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290513.
Повний текст джерелаLI, BO. "UV-LIGA COMPATIBLE ELECTROFORMED NANO-STRUCTURED MATERIALS FOR MICRO MECHANICAL SYSTEMS." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2269.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
Bayati, Marzieh. "Electrokinetic manipulation of micro- and nano-structured materials in microfabricated devices." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706139.
Повний текст джерелаSkrypnychuk, Vasyl. "Vertical charge transport in conjugated polymers." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-133180.
Повний текст джерелаAggarwal, Ankur. "Chip-Package Nano-Structured Copper and Nickel Interconnections with Metallic and Polymeric Bonding Interfaces." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14096.
Повний текст джерела