Os autores agradecem M. Leboeuf para a assistência com o, AFM W. Lee para o mestre de alumínio texturizado e anodicamente o Escritório Federal Suíço de Energia eo Swiss National Science Foundation para financiamento. Uma parte deste trabalho foi realizado no âmbito do projecto FP7 &quot;Fast Track&quot;, financiado pela CE ao abrigo da convenção de subvenção não 283,501.

1. Fabricação de Moldes Usamos a nossa configuração nanoimpressão casa construída para a fabricação do molde negativo Ref seguinte. 6, mas qualquer configuração de nanoimpressão alternativa irá funcionar bem. Alternativamente um molde funcionalizada polidimetilsiloxano (PDMS) também pode funcionar. <ol><li> Fabricar ou comprar um mestre adequado transportando o padrão de nanoescala a ser transferido. Em princípio, qualquer mestre adequado para nanoimpressão irá fazer o trabalho. Nós usamos uma camada de ZnO texturado sobre uma folha de vidro (Schott, AF32 eco, 41 milímetros x 41 mm x 0,5 mm), depositado como indicado em 3.1 como uma estrutura mestre para ilustrar o método. </li><li> Aplicar uma camada de anti-adesão sobre a estrutura mestre, tal como descrito em 2. </li><li> Limpar um polietileno naftalato folha (PEN) (Goodfellow, 82 mm x 41 mm x 0,125 mm) num banho de acetona de ultra-sons durante 2 minutos, seguido por um banho de ultra-sons de isopropanol durante 2 min mais. Lavar mais uma vez com isopropanol e seque com nitrogênio. </li><li> Depósito de uma camada de adesão sputtered Cr (nm 5-10) na folha de PEN. </li><li> Spin-revestimento da resina curável por UV (Microresist, Ormocer, 1-2 ml) na folha PEN a 5000 rpm para obter uma cobertura uniforme. </li><li> Realizar um pré-cozimento durante 5 minutos numa placa de aquecimento a 80 ° C para evaporar o solvente, melhorar a uniformidade da película e aderência à folha de PEN. </li><li> Use sua configuração nanoimpressão para carimbar o modelo mestre em resina de cura UV. Embora não seja obrigatório, realizamos estampagem sob vácuo, para evitar inclusões de bolha por aplicação de uma pressão de 1 bar homogéneo para uma membrana de silicone flexível. Na nossa configuração, a membrana de silicone separa a câmara de vácuo em dois sub-compartimentos. A pressão é gerada por ventilação do compartimento superior, enquanto que o compartimento inferior permanece sob vácuo. Ventilação empurra a membrana flexível na direcção do fundo de iniciar a estampagem. </li><li> Expor a resina a luz UV de provocar a reacção de reticulação da resina. Nós aplicamos uma luz moderadaintensidade de 1,4 mW / cm 2 no comprimento de onda de 365 nm, fornecidos por vários LEDs. Tempo de exposição através da folha de PEN é tipicamente de 15-20 minutos. </li><li> Cuidadosamente desmoldagem manualmente descascar o molde fora da estrutura principal. </li><li> À medida que a resina pode ser submetido a retracção ligeira durante a deposição do material funcional, o que pode levar à descamação espontânea, realizamos uma ligeira coza pós térmico a 150 ° C durante 6-8 horas em um forno com atmosfera ambiente antes do processamento adicional. </li></ol> 2. Anti-adesão Camada Para a desmoldagem bem sucedido, a camada de anti-adesão deve ser adaptado para os materiais e a rugosidade padrão. Padrões geralmente ásperas requerem baixos coeficientes de atrito. Baixos coeficientes de furar em padrões lisos podem levar a descamação do material funcional a partir do molde. Elevados coeficientes de furar em padrões irregulares podem resultar na descamação da resina a partir da folha PEN durante a fabricação do molde como a aderênciasce da resina para o mestre é mais forte. <ol><li> Revestir o molde (ou principal) com uma camada de crómio sputtered (nm 5-10) para promover a adesão do agente de anti-aderência. Para padrões lisos nós cair este passo. Em alguns casos, a camada de crómio pode impedir que o agente de anti-adesão de estrutura etch mestre. </li><li> Aplicar uma pequena gota de agente anti-adesão (Sigma-Aldrich, (1H, 1H, 2H, 2H-Perfluoroctyl)-trichlorsilane) numa lâmina de vidro. Colocar a placa de vidro, juntamente com o molde numa câmara de vácuo e uma bomba para baixo. O agente de anti-adesão e evapora-se depositar como uma monocamada molecular sobre o molde. </li><li> Ancorar o agente de anti-adesão por meio de recozimento durante 1-2 horas a 80 ° C. </li></ol> 3. A deposição de material Nós demonstramos aqui três técnicas de deposição adequadas para deposição de material para ilustrar a versatilidade do nanomoulding. Outras técnicas de deposição pode também ser aplicada. O terceiro exemplo descreve a fabrication de um completo célula de silício de filme fino solar. <ol><li> A deposição química de vapor (CVD) de óxido de zinco: Coloque o molde para a placa de aquecimento do reactor CVD aquecido a 180 ° C. Utilizar uma estrutura de metal para evitar a curvatura do molde durante a deposição de ZnO PEN. Fechar o reator, bomba para baixo e permitir termalização. Admitir os gases precursores (H 2 O, e (C 2 H 5) 2 Zn). Além disso dose que pequenas quantidades de B 2 H 6 por doping. A espessura da camada de ZnO é proporcional ao tempo de deposição. Usamos ZnO espessuras de camada de geralmente 1-5 ^ m. Detalhes sobre parâmetros típicos deposições podem ser encontradas na referência 7. </li><li> Physical Vapor Deposition (PVD) / sputtering de prata: Coloque o molde para o sistema PVD. Feche o sistema e bombear para baixo. Admita gás argônio processo. Ligue o gerador de corrente contínua. A espessura da camada Ag é novamente proporcional ao tempo de deposição. Usamos Ag espessuras de camada, tipicamente de 1 um. P deposição típicaARÂMETROS são uma pressão de árgon de 5.5x10 -3 mbar e uma instalação de alimentação de CC específica de 250 W que produzam uma velocidade de deposição de cerca de 45 nm / seg. </li><li> Plasma melhorada deposição de vapor químico (CVD-PE): Depósito ZnO como em 3.1). Coloque o molde para o reactor de PE-CVD aquecido a 200 ° C. Fechar o reator, bomba para baixo e permitir termalização. Admitir os gases precursores (SiH 4 e H 2). Em adição, pequenas quantidades de dose de B (CH 3) 3 e PH 3 para conseguir a dopagem p e tipo-n, respectivamente. Para aumentar a tensão de circuito aberto de células solares, também usar pequenas quantidades de CH 4 e CO 2 para as camadas dopadas. Após a deposição da pilha de silício amorfo pino da célula solar, que deposita uma backcontact ZnO como descrito em 3.1. </li><li> Evitar a flexão excessiva do molde, tal como flexão poderia causar descamação da camada depositada. </li></ol> 4. Transferência de camada Usamos glaslâminas s (Schott AF32 eco, 41 milímetros x 41 mm x 0,5 mm) como substrato final. Mas outros substratos, incluindo folhas de metal ou folhas de polímeros, pode ser utilizado como alternativa. <ol><li> Lâminas de vidro limpas com acetona e isopropanol e golpe seco com nitrogênio. </li><li> Spin-revestimento de resina curável por UV (Microresist, Ormocer, 1-2 ml) na lâmina de vidro a 5000 rpm. </li><li> Use sua configuração nanoimpressão para ancorar o molde transporte as camadas depositadas sobre o substrato final. Como para carimbar, realizamos ancoragem sob vácuo, aplicando uma pressão homogênea de um bar. </li><li> Expor a resina a luz UV de provocar a reacção de reticulação. Aplicamos uma intensidade moderada de 1,4 mW / cm 2 no comprimento de onda de 365 nm, fornecidos por vários LEDs. Tempo de exposição através da lâmina de vidro é apenas 1-3 min, devido à elevada taxa de transmissão de UV de vidro em comparação com o PEN. </li><li> Desmoldagem manualmente descascar o molde fora da lâmina de vidro. </li></ol> 5. Caracterização da Amostra <ol&gt; <li> Use o seu favorito técnica, morfológica elétrica ou óptica para caracterizar as amostras nanomoulded. Aqui nós caracterizar nossas amostras nanomoulded usando microscopia eletrônica de varredura (MEV) e microscopia de força atômica (AFM). </li></ol>

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	<li>Geissler, M., Xia, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patterning:+Principles+and+Some+New+Developments.">Patterning: Principles and Some New Developments.</a> Advanced Materials. 16 (15), 1249-1269 (2004).</li><li>Guo, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoimprint+Lithography:+Methods+and+Material+Requirements.">Nanoimprint Lithography: Methods and Material Requirements.</a> Advanced Materials. 19, 495-513 (2007).</li><li>Ahn, S. H., Guo, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-Area+Roll-to-Roll+and+Roll-to-Plate+Nanoimprint+Lithography:+A+Step+toward+High-Throughput.">Large-Area Roll-to-Roll and Roll-to-Plate Nanoimprint Lithography: A Step toward High-Throughput.</a> Application of Continuous Nanoimprinting. ACS Nano. 3 (8), 2304-2310 (2009).</li><li>Battaglia, C., Escarr&#233;, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoimprint+Lithography+for+High-Efficiency+Thin-Film+Silicon+Solar+Cells.">Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells.</a> Nano Letters. 11, 661-665 (2011).</li><li>Battaglia, C., Escarr&#233;, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanomoulding+of+Transparent+Zinc+Oxide+Electrodes+for+Efficient+Light+Trapping+in+Solar+Cells.">Nanomoulding of Transparent Zinc Oxide Electrodes for Efficient Light Trapping in Solar Cells.</a> Nature Photonics. 5, 535-538 (2012).</li><li>Escarr&#233;, J., S&#246;derstr&#246;m, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Fidelity+Transfer+of+Nanometric+Random+Textures+by+UV+Embossing+for+Thin+Film+Solar+Cells+Applications.">High Fidelity Transfer of Nanometric Random Textures by UV Embossing for Thin Film Solar Cells Applications.</a> Solar Energy Materials &amp; Solar Cells. 95, 881-886 (2011).</li><li>Fa&#255;, S., Feitknecht, L., Schl&#252;chter, R., Kroll, U., Vallat-Sauvain, E., Shah, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rough+ZnO+layers+by+LP-CVD+process+and+their+effect+in+improving+performances+of+amorphous+and+microcrystalline+silicon+solar+cells.">Rough ZnO layers by LP-CVD process and their effect in improving performances of amorphous and microcrystalline silicon solar cells.</a> Solar Energy Materials and Solar Cells. 90, 2960-2967 (2006).</li><li>Zhao, X. -. M., Xia, Y., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+Three-Dimensional+Micro-Structures:+Microtransfer+Molding.">Fabrication of Three-Dimensional Micro-Structures: Microtransfer Molding.</a> Advanced Materials. 8, 837-840 (1996).</li><li>Hampton, M. J., Williams, S. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Patterning+of+Sub-500+nm+Inorganic+Oxide+Structures.">The Patterning of Sub-500 nm Inorganic Oxide Structures.</a> Advanced Materials. 20, 2667-2673 (2008).</li><li>Bass, J. D., Schaper, C. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfer+Molding+of+Nanoscale+Oxides+Using+Water-Soluble+Templates.">Transfer Molding of Nanoscale Oxides Using Water-Soluble Templates.</a> ACS Nano. 5 (5), 4065-4072 (2011).</li><li>Escarr&#233;, J., Nicolay, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanomoulded+front+ZnO+contacts+for+thin+film+silicon+solar+cell+applications.">Nanomoulded front ZnO contacts for thin film silicon solar cell applications.</a> , (2012).</li><li>Sontheimer, T., Rudigier-Voigt, E., Bockmeyer, M., Klimm, C., Schubert-Bischoff, P., Becker, C., Rech, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-area+fabrication+of+equidistant+free-standing+Si+crystals+on+nanoimprinted+glass.">Large-area fabrication of equidistant free-standing Si crystals on nanoimprinted glass.</a> Phys. Status Solidi. RRL. 5, 376-379 (2011).</li></ol>

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Nanomoulding permite a transferência de nanopatterns sobre arbitrárias materiais funcionais. Comparação das etapas de processamento individuais da Figura 1 e 2 revela a estreita relação entre nanomoulding e nanoimpressão. A principal diferença entre nanomoulding e nanoimpressão é a etapa de deposição de material adicional na Figura 2e. O fluxo do processo restante é idêntico. Nanomoulding pode, portanto, ser realizada em qualquer configuração nanoimpress...

Microusinagem ganhou importância enorme em muitas áreas de nanotecnologia e ciências aplicadas. Geração de padrões é o primeiro passo e pode ser realizada por abordagens de cima para baixo, como a litografia por feixe de elétrons ou de baixo para cima abordagens baseadas em auto-montagem de métodos tais como a litografia de nanoesferas ou copolímero em bloco de litografia 1. Tão importante quanto a geração de padrões é a replicação padrão. Além fotolitografia, nanoimpressão (Figura 1) tem emergido como uma alternativa promissora, em particular adequado para a modelação de alto rendimento de grande área a baixo custo em nanoescala 2-4. Enquanto fotolitografia requer uma máscara padronizada, nanoimpressão se baseia em uma estrutura pré-fabricada mestre. Transferência de padrão do mestre é normalmente realizada em um termoplástico ou um polímero ou UV-curável termicamente. No entanto, existem muitos casos em que é desejável para transferir o padrão directamente sobre um material funcional. &lt;classe p = &quot;jove_content&quot;&gt; Aqui descrevemos um método baseado em replicação e transferência nanomoulding camada (Figura 2) que, recentemente introduzida em Ref. 5 para transferir os padrões em nanoescala para eléctrodos de óxido de zinco funcionais. O nosso método de nanomoulding pode ser facilmente implementado, se uma instalação de nanoimpressão está disponível. Nanomoulding oferece o potencial de ser generalizada para muitos outros materiais funcionais, pilhas de materiais e dispositivos, mesmo completa, desde que o material do molde é escolhido de tal forma que é compatível com o processo de deposição de material (es). Como exemplo, aqui presentes nanomoulding de condutor transparente de óxido de zinco (ZnO) eletrodos depositados por deposição química a vapor (CVD), que encontram a sua aplicação para melhorar a captura de luz em células solares 5.

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de Catálogo </td><td> Comentários (opcional) </td></tr><tr><td> Resina nanoimpressão </td><td> Microresist </td><td> Ormostamp </td><td></td></tr><tr><td> (1H, 1H, 2H, 2H-Perfluoroctyl)-trichlorsilane, agente anti-aderência </td><td> Sigma Aldrich </td><td> 448931-10G </td><td></td></tr><tr><td> Lâminas de vidro </td><td> Schott </td><td> AF32 eco </td><td> 0,5 milímetros </td></tr><tr><td> Naftalato polietileno (PEN) folhas </td><td> Goodfellow </td><td> ES361090 </td><td> 0,125 milímetro </td></tr><tr><td> (C 2 H 5) 2 Zn </td><td> Akzo Nobel </td><td></td><td></td></tr><tr><td> Ag sputter 4N alvo </td><td> Heraeus </td><td> 81062165 </td><td></td></tr><tr><td> B 2 H 6, SiH 4, H 2, B (CH 3) 3, PH 3, CH 4, CO 2 </td><td> Messer </td><td></td><td></td></tr><tr><td></td><td></td><td></td><td> EQUIPAMENTOS </td></tr><tr><td> Nanoimpressão sistema </td><td> Home-construído </td><td></td><td></td></tr><tr><td> LP-CVD sistema </td><td> Home-construído </td><td></td><td></td></tr><tr><td> PVD sistema </td><td> Leybold </td><td> Univex 450 B </td><td></td></tr><tr><td> PE-CVD reactor </td><td> Indeotec </td><td> Polvo I </td><td></td></tr><tr><td> SEM </td><td> JEOL </td><td> JSM-7500 TFE </td><td></td></tr><tr><td> AFM </td><td> Instrumentos Digitais </td><td> Nanoscope 3100 </td><td></td></tr></tbody></table>

nanomoulding of functional materials, a versatile complementary pattern replication method to nanoimprinting

Descrevemos uma técnica que permite que nanomoulding baixo custo nanoescala padronização de materiais funcionais, pilhas de materiais e dispositivos completos. Nanomoulding combinada com a transferência da camada permite a replicação de padrões de superfície a partir de uma estrutura arbitrárias mestre para o material funcional. Nanomoulding pode ser realizada em qualquer configuração de nanoimpressão e pode ser aplicado a uma grande variedade de materiais e processos de deposição. Em particular, demonstrar a fabricação de eletrodos de óxido de zinco estampados transparentes para aplicações leves de aprisionamento em células solares.

<html> A Figura 3 resume alguns exemplos ilustrativos de estruturas nanomoulded. Uma estrutura mestre ZnO crescidos por CVD no vidro é mostrada em (a). O correspondente nanomoulded ZnO réplica é mostrado em (d). Comparação da altura do local (g) e (j) do ângulo histogramas extraídos de imagens de AFM revela a alta fidelidade do processo de nanomoulding. Resultados análogos são mostrados por uma grade unidimensional fabricados por litografia interferência (b, e, h, k) e alumínio anodicamente te...

Watch this Scientific Journal Video about Nanomoulding of Functional Materials, a Versatile Complementary Pattern Replication Method to Nanoimprinting at JoVE.com

Nanomoulding of Functional Materials, a Versatile Complementary Pattern Replication Method to Nanoimprinting

Descrevemos uma técnica que permite que nanomoulding baixo custo nanoescala padronização de materiais funcionais, pilhas de materiais e dispositivos completos. Nanomoulding pode ser realizada em qualquer configuração de nanoimpressão e pode ser aplicado a uma grande variedade de materiais e processos de deposição.

Nanomoulding de Materiais Funcionais, um método de replicação Versátil Complementar Padrão para nanoimpressão

We describe a nanomoulding technique which  allows low-cost nanoscale patterning of functional materials, materials stacks  and full devices. Nanomoulding ...

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11.6K visualizações.  Ecole Polytechnique Fédérale de Lausanne (EPFL). Descrevemos uma técnica que permite que nanomoulding baixo custo nanoescala padronização de materiais funcionais, pilhas de materiais e dispositivos completos. Nanomoulding pode ser realizada em qualquer configuração de nanoimpressão e pode ser aplicado a uma grande variedade de materiais e processos de deposição.

Vídeo: Nanomoulding of Functional Materials, a Versatile Complementary Pattern Replication Method to Nanoimprinting

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

Usando neutron spin echo resolvi a dispersão da incidência de pastagem para investigar materiais orgânicos de células solares

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

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Casting Protocols for the Production of Open Cell Aluminum Foams by the Replication Technique and the Effect on Porosity

Metal foams are interesting materials from both a fundamental understanding and practical applications point of view. Uses have been proposed, and in many cases validated experimentally, for light weight or impact energy absorbing structures, as high surface area heat exchangers or electrodes, as implants to the body, and many more. Although great progress has been made in understanding their structure-properties relationships, the large number of different processing techniques, each producing material with different characteristics and structure, means that understanding of the individual effects of all aspects of structure is not complete. The replication process, where molten metal is infiltrated between grains of a removable preform material, allows a markedly high degree of control and has been used to good effect to elucidate some of these relationships. Nevertheless, the process has many steps that are dependent on individual &#8220;know-how&#8221;, and this paper aims to provide a detailed description of all stages of one embodiment of this processing method, using materials and equipment that would be relatively easy to set up in a research environment. The goal of this protocol and its variants is to produce metal foams in an effective and simple way, giving the possibility to tailor the outcome of the samples by modifying certain steps within the process. By following this, open cell aluminum foams with pore sizes of 1&#8211;2.36 mm diameter and 61% to 77% porosity can be obtained.

Replication is one of the processing techniques used for the production of porous metal sponges. In this paper one implementation of the method for the production of open celled porous aluminum is shown in detail.

Fundição protocolos para a Produção de Abra a pilha de alumínio Espumas pela técnica de replicação e o Efeito da porosidade

Metal foams are interesting materials from both a fundamental understanding and practical applications point of view. Uses have been proposed, and in many ...

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the balls. Among other applications, it is a versatile technique that allows for effective preparation of gasless reactive nanostructured materials with high energy density per volume (Ni+Al, Ta+C, Ti+C). The structural transformations of reactive media, which take place during HEBM, define the reaction mechanism in the produced energetic&#160;composites. Varying the processing conditions permits fine tuning of the milling-induced microstructures of the fabricated composite particles. In turn, the reactivity, i.e., self-ignition temperature, ignition delay time, as well as reaction kinetics, of high energy density materials depends on its microstructure. Analysis of the milling-induced microstructures suggests that the formation of fresh oxygen-free intimate high surface area contacts between the reagents is responsible for the enhancement of their reactivity. This manifests itself in a reduction of ignition temperature and delay time, an increased rate of chemical reaction, and an overall decrease of the effective activation energy of the reaction. The protocol provides a detailed description for the preparation of reactive nanocomposites with tailored microstructure using short-term HEBM method. It also describes a high-speed thermal imaging technique to determine the ignition/combustion characteristics of the energetic materials. The protocol can be adapted to preparation and characterization of a variety of nanostructured energetic composites.

This protocol describes the preparation of gasless nanostructured energetic materials (Ni+Al, Ta+C, Ti+C) using the short-term high-energy ball milling (HEBM) technique. It also describes a high-speed thermal imaging method to study the reactivity of mechanically fabricated nanocomposites. These protocols can be extended to other reactive nanostructured energetic materials.

Preparação e reactividade de Gasless Nanostructured materiais energéticos

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

Síntese e funcionalização de 3D Materiais Nano-grafeno Grafeno: Aerogels e grafeno Assembléias Macro

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Métodos experimentais avançados para baixa temperatura Magnetotransporte Medição de novos materiais

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency are needed to evaluate and optimize sampling protocols. The approach described here is designed to provide this measurement infrastructure, and controls most of the factors known to be relevant to wipe-sampling. Three critical factors (the applied force, travel distance, and travel speed) are controlled using an automated device. Test surfaces are chosen based on similarity to the screening environment, and the wipes can be made from any material considered for use in wipe-sampling. Particle samples of the explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) are applied in a fixed location on the surface using a dry-transfer technique. The particle samples, recently developed to simulate residues made after handling explosives, are produced by inkjet printing of RDX solutions onto polytetrafluoroethylene (PTFE) substrates. Collection efficiency is measured by extracting collected explosive from the wipe, and then related to critical sampling factors and the selection of wipe material and test surface. These measurements are meant to guide the development of sampling protocols at screening venues, where speed and throughput are primary considerations.

Optimized sampling protocols and the development of new wipe materials can be facilitated by standardized measurements of collection efficiency from wipe-sampling. Our approach for sampling trace explosives uses an automated device to control speed, force, and distance during wipe-sampling followed by extraction of collected explosives.

Método Padrão para medir a eficiência Coleção de Wipe-amostragem de Explosivos Traço

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

Um novo método para<em&gt; In Situ</em&gt; Caracterização eletromecânica de amostras de nanoescala

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

A Fabrication and Measurement Method for a Flexible Ferroelectric Element Based on Van Der Waals Heteroepitaxy

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on high-density data storage and low-power consumption capabilities. However, the high-quality oxide based nonvolatile memory on flexible substrates is often constrained by the material characteristics and the inevitable high-temperature fabrication process. In this paper, a protocol is proposed to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica. The versatile deposition technique and measurement method enable the fabrication of flexible yet single-crystalline non-volatile memory elements necessary for the next generation of smart devices.

In this paper, we present a protocol to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica.

Um método de medição para um elemento ferroelétrica flexível baseado em Heteroepitaxy de Van Der Waals e fabricação

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on ...

Multiscale Structures Aggregated by Imprinted Nanofibers for Functional Surfaces

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing challenge in the field is the fabrication of hybrid micro-nano structures using a facile, cost-effective, and high-throughput method. To overcome these challenges, this paper proposes a protocol to fabricate multiscale structures using only an imprint process with an anodic aluminum oxide (AAO) filter and an evaporative self-aggregation process of nanofibers. Unlike previous attempts that have aimed to straighten nanofibers, we demonstrate a unique fabrication method for multiscale aggregated nanofibers with high aspect ratios. Furthermore, the surface morphology and wettability of these structures on various liquids were investigated to facilitate their use in multifunctional surfaces.

Presented is an easy method to fabricate nano-micro multiscale structures, for functional surfaces, by aggregating nanofibers fabricated using an anodic aluminum oxide filter.

Estruturas de múltipla escala agregadas por nanofibras impressos para superfícies funcionais

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing ...

Studying Large Amplitude Oscillatory Shear Response of Soft Materials

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl sulfoxide (DMSO) and xanthan gum in water &#8212; two concentrated polymer solutions used as viscosifiers in foods, enhanced oil recovery, and soil remediation. Understanding the nonlinear rheological behavior of soft materials is important in the design and controlled manufacturing of many consumer products. It is shown how the response to LAOS of these polymer solutions can be interpreted in terms of a clear transition from linear viscoelasticity to viscoplastic deformation and back again during a period. The LAOS results are analyzed via the fully quantitative Sequence of Physical Processes (SPP) technique, using free MATLAB-based software. A detailed protocol of performing a LAOS measurement with a commercial rheometer, analyzing nonlinear stress responses with the freeware, and interpreting physical processes under LAOS is presented. It is further shown that, within the SPP framework, a LAOS response contains information regarding the linear viscoelasticity, the transient flow curves, and the critical strain responsible for the onset of nonlinearity.

We present a detailed protocol outlining how to perform nonlinear oscillatory shear rheology on soft materials, and how to run the SPP-LAOS analysis to understand the responses as a sequence of physical processes.

Estudar a resposta de grande Amplitude oscilatória de materiais macios

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl ...