Gli autori ringraziano M. Leboeuf per l&#39;assistenza con l&#39;, AFM W. Lee per il master in alluminio anodicamente texture e l&#39;Ufficio svizzero dell&#39;energia federale e il Fondo nazionale svizzero Science Foundation per il finanziamento. Una parte di questo lavoro è stato svolto nell&#39;ambito del progetto FP7 &quot;Fast Track&quot;, finanziato dalla CE nell&#39;ambito convenzione di sovvenzione n 283501.

1. Mould Fabrication Usiamo la nostra casa costruita configurazione nanoimprinting per la realizzazione del Rif stampo negativo seguente. 6, ma ogni installazione nanoimprinting alternativa vanno bene. In alternativa, un funzionalizzato polidimetilsilossano (PDMS) muffa potrebbe anche funzionare. <ol><li> Realizzare o comprare un master per il trasporto adatta il modello da trasferire su scala nanometrica. In linea di principio, qualsiasi master adatto per nanoimprinting farà il lavoro. Usiamo un livello di texture ZnO su una lastra di vetro (Schott, AF32 eco, 41 mm x 41 mm x 0,5 mm) depositati come descritto al punto 3.1 come struttura principale per illustrare il metodo. </li><li> Applicare un anti-aderenza strato sulla struttura principale come descritto in 2. </li><li> Pulire un polietilene naftalato (PEN) foglio (Goodfellow, 82 mm x 41 mm x 0,125 mm) in un bagno ad ultrasuoni acetone per 2 min seguita da un bagno ad ultrasuoni isopropanolo per altri 2 minuti. Risciacquare una volta con isopropanolo e asciugare con azoto. </li><li> Deposito di una polverizzazione catodica strato di adesione Cr (nm 5-10) sul foglio PEN. </li><li> Spin-coat l&#39;UV-curable resina (Microresist, Ormocer, 1-2 ml) sul foglio PEN a 5.000 giri per ottenere una copertura uniforme. </li><li> Eseguire un prebake per 5 min su una piastra calda a 80 ° C per evaporare il solvente, migliorare l&#39;uniformità di pellicola e l&#39;adesione al foglio PEN. </li><li> Utilizzare la configurazione nanoimprinting per timbrare l&#39;archetipo maestro nel UV-curable resina. Sebbene non obbligatorio, eseguiamo stampaggio sotto vuoto per evitare inclusioni bolla applicando una pressione omogenea di 1 bar su una membrana di silicone flessibile. Nella nostra configurazione, la membrana di silicone separa la camera a vuoto in due sotto-compartimenti. Pressione viene generata facendo fuoriuscire il vano superiore, mentre il vano inferiore rimane sotto vuoto. Sfiato spinge la membrana flessibile verso il basso di avvio del calpestio. </li><li> Esporre la resina a luce UV per provocare la reazione di reticolazione della resina. Applichiamo una luce moderataintensità di 1,4 mW / cm 2 alla lunghezza d&#39;onda di 365 nm fornite da diversi LED. Tempo di esposizione attraverso il foglio PEN è in genere 15-20 minuti. </li><li> Cura sformare manualmente peeling lo stampo fuori dalla struttura principale. </li><li> Come resina può subire lieve ritiro durante la deposizione del materiale funzionale, che può portare a spontanea peeling, si esegue una cottura lieve messaggio termico a 150 ° C durante 6-8 ore in un forno ad atmosfera ambiente prima di procedere. </li></ol> 2. Anti-adesione livello Per successo sformatura, l&#39;anti-aderenza strato deve essere adattata ai materiali e la rugosità pattern. In genere i modelli grezzi richiedono bassi coefficienti di attaccare. Bassi coefficienti sporgenti su modelli lisce può portare alla pelatura del materiale funzionale dallo stampo. Elevati coefficienti di attaccare sui modelli grezzi può causare secchezza della resina dal foglio PEN durante la fabbricazione dello stampo come l&#39;aderenza deice della resina al master è più forte. <ol><li> Rivestire lo stampo (o master) con uno strato di cromo per polverizzazione catodica (nm 5-10) per promuovere l&#39;adesione del movimento anti-adesione agente. Per i modelli liscio lasciamo cadere questo passo. In alcuni casi lo strato di cromo può impedire l&#39;agente anti-adesione per incidere la struttura master. </li><li> Applicare una piccola goccia di agente anti-adesione (Sigma-Aldrich, (1H, 1H, 2H, 2H-Perfluoroctyl)-trichlorsilane) su un vetrino. Mettere il vetrino con lo stampo in una camera a vuoto di gas e liquidi. L&#39;agente anti-aderenza evapora e deposita come un monostrato molecolare sullo stampo. </li><li> Ancorare il anti-adesione agente tramite ricottura durante 1-2 ore a 80 ° C. </li></ol> 3. Materiale di deposizione Dimostriamo qui tre tecniche di deposizione adatti per la deposizione di materiale per illustrare la versatilità di nanomoulding. Altre tecniche di deposizione potrebbe anche essere applicata. Il terzo esempio descrive la fabrication di una completa a film sottile cella solare al silicio. <ol><li> Deposizione di vapore chimico (CVD) di ossido di zinco: Mettere lo stampo sulla piastra riscaldante del reattore CVD riscaldato a 180 ° C. Utilizzare un telaio metallico per evitare di piegare dello stampo PEN durante la deposizione ZnO. Chiudere il reattore, pompa e consentire termalizzazione. Ammettere il gas precursori (H 2 O e (C 2 H 5) 2 Zn). Inoltre abbiamo dosaggio di piccole quantità di B 2 H 6 per doping. Lo spessore dello strato di ZnO è proporzionale al tempo di deposizione. Usiamo strato ZnO tipicamente spessori di 1-5 micron. Dettagli su parametri tipici deposizioni possono essere trovati in rif. 7 </li><li> Deposizione fisica da fase vapore (PVD) / sputtering di argento: Mettete lo stampo nel sistema PVD. Chiudere l&#39;impianto di gas e liquidi. Ammettere gas di processo argon. Accendere il generatore di corrente continua. Lo spessore dello strato di Ag è nuovamente proporzionale al tempo di deposizione. Usiamo strato di Ag spessore, in genere di 1 um. Deposizione p tipicaarametri sono una pressione di argon 5.5x10 -3 mbar e una potenza specifica di installazione continua di 250 W che producono una velocità di deposizione di circa 45 nm / sec. </li><li> Plasma-enhanced Chemical Vapor Deposition (PE-CVD): Deposito ZnO come in 3.1). Mettere lo stampo in PE-CVD reattore riscaldato a 200 ° C. Chiudere il reattore, pompa e consentire termalizzazione. Ammettere i gas precursori (SiH 4 e H 2). Inoltre abbiamo dosi piccole quantità di B (CH 3) 3 e PH 3 per ottenere p-doping e di tipo n, rispettivamente. Per aumentare la tensione a circuito aperto delle celle solari, usiamo anche piccole quantità di CH 4 e CO 2 per gli strati drogati. Dopo la deposizione del amorfo pila perno cella solare al silicio, si deposita una backcontact ZnO, come descritto al punto 3.1. </li><li> Evitare un&#39;eccessiva flessione dello stampo, la piegatura può causare spellatura dello strato depositato. </li></ol> 4. Strato di trasferimento Usiamo glasdiapositive s (Schott AF32 eco, 41 mm x 41 mm x 0,5 mm) come substrato finale. Ma altri substrati, compresi fogli di metallo o fogli polimerici, potrebbe essere usato in alternativa. <ol><li> Vetrini puliti con acetone e isopropanolo e asciugare con azoto. </li><li> Spin-coat UV resina induribile (Microresist, Ormocer, 1-2 ml) sul vetrino a 5.000 giri. </li><li> Utilizzare la configurazione nanoimprinting per ancorare il porta-stampo gli strati depositati sul substrato finale. Come per stampaggio, si eseguono ancoraggio sotto vuoto applicando una pressione omogenea di 1 bar. </li><li> Esporre la resina a luce UV per provocare la reazione di reticolazione. Si applica una moderata intensità di 1,4 mW / cm 2 alla lunghezza d&#39;onda di 365 nm fornite da diversi LED. Tempo di esposizione attraverso il vetrino è solo 1-3 min per effetto della trasmissione UV superiore del vetro rispetto al PEN. </li><li> Sformare manualmente peeling lo stampo fuori dal vetrino. </li></ol> 5. Esempio di Caratterizzazione <ol&gt; <li> Usa il tuo preferito morfologica, tecnica elettrica o ottica per caratterizzare i campioni nanomoulded. Qui si caratterizzano i nostri campioni nanomoulded usando la microscopia elettronica a scansione (SEM) e microscopia a forza atomica (AFM). </li></ol>

<ol>
	<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>

Nessun conflitto di interessi dichiarati.

Nanomoulding consente il trasferimento di nanopatterns su arbitrarie materiali funzionali. Confronto delle singole fasi di lavorazione in figura 1 e 2 rivela la stretta relazione tra nanomoulding e nanoimprinting. La principale differenza tra nanomoulding e nanoimprinting è l&#39;ulteriore fase di deposizione di materiale in figura 2e. Il flusso di processo rimanente è identico. Nanomoulding possono quindi essere eseguite su qualsiasi configurazione nanoimprinting dis...

Nanopatterning ha assunto un&#39;importanza enorme in molti campi delle nanotecnologie e delle scienze applicate. Generazione di modello è il primo passo e può essere realizzata mediante top-down approcci come litografia a fascio elettronico o bottom-up basato sulla auto-assemblaggio metodi come la litografia nanosfere o copolimero a blocchi litografia 1. Importante come generazione di un modello è la replica del modello. Oltre fotolitografia, nanoimprinting (Figura 1) è emerso come una promettente alternativa, in particolare, adatto per high-throughput di grande superficie patterning su scala nanometrica a basso costo 2-4. Mentre fotolitografia richiede una maschera modellata, nanoimprinting si basa su una struttura prefabbricata maestro. Trasferimento del modello dal master viene comunemente eseguita in un polimero termoplastico o UV-induribile o termicamente. Tuttavia vi sono molti casi in cui è desiderabile trasferire il pattern direttamente su un materiale funzionale. &lt;p class = &quot;jove_content&quot;&gt; Qui si descrive un metodo di replica basata su nanomoulding e strato di trasferimento (figura 2) che abbiamo recentemente introdotto in rif. 5 per trasferire modelli nanoscala su elettrodi funzionali di ossido di zinco. Nanomoulding nostro metodo può essere facilmente implementato se una configurazione nanoimprinting è disponibile. Nanomoulding offre il potenziale per essere generalizzato a molti altri materiali funzionali, pile materiali e dispositivi persino interi, a condizione che il materiale di stampo è scelto in modo che sia compatibile con il processo di deposizione di materiale (es). Come esempio qui presentiamo nanomoulding del conduttore trasparente di ossido di zinco (ZnO) elettrodi depositati mediante deposizione chimica da fase vapore (CVD), che trovano applicazione per migliorare cattura la luce nelle celle solari 5.

<table border="1"><tbody><tr><td> Nome del reagente </td><td> Azienda </td><td> Numero di catalogo </td><td> Commenti (opzionale) </td></tr><tr><td> Nanoimprinting resina </td><td> Microresist </td><td> Ormostamp </td><td></td></tr><tr><td> (1H, 1H, 2H, 2H-Perfluoroctyl)-trichlorsilane, agente anti-aderenza </td><td> Sigma Aldrich </td><td> 448931-10G </td><td></td></tr><tr><td> Diapositiva su vetro </td><td> Schott </td><td> AF32 eco </td><td> 0,5 millimetri </td></tr><tr><td> Polietilene naftalato (PEN) fogli </td><td> Goodfellow </td><td> ES361090 </td><td> 0,125 millimetri </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 bersaglio </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> ATTREZZATURE </td></tr><tr><td> Nanoimprinting sistema </td><td> Home-costruito </td><td></td><td></td></tr><tr><td> LP-CVD sistema </td><td> Home-costruito </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 reattore </td><td> Indeotec </td><td> Octopus 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> Gli strumenti digitali </td><td> Nanoscope 3100 </td><td></td></tr></tbody></table>

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

Descriviamo una tecnica che permette di nanomoulding basso costo patterning su scala nanometrica di materiali funzionali, pile di materiali e dispositivi completi. Nanomoulding combinato con trasferimento strato consente la replicazione di modelli di superficie arbitrarie da una struttura master sul materiale funzionale. Nanomoulding possono essere eseguite su qualsiasi configurazione nanoimprinting e può essere applicata a una vasta gamma di materiali e processi di deposizione. In particolare, abbiamo dimostrato la fabbricazione di elettrodi di zinco trasparente di ossido di fantasia per le applicazioni di cattura della luce nelle celle solari.

<html> Figura 3 riassume alcuni esempi illustrativi di strutture nanomoulded. Una struttura master ZnO cresciuti CVD su vetro è mostrato in (a). Il corrispondente nanomoulded ZnO replica è mostrato in (d). Confronto dell&#39;altezza locale (g) e angolo (j) istogrammi estratti da immagini AFM rivelano l&#39;alta fedeltà del processo nanomoulding. Risultati analoghi sono indicati per un reticolo unidimensionale fabbricato da litografia interferenza (b, e, h, k) e alluminio anodicamente strutturato (c, f...

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

Descriviamo una tecnica che permette di nanomoulding basso costo patterning su scala nanometrica di materiali funzionali, pile di materiali e dispositivi completi. Nanomoulding possono essere eseguite su qualsiasi configurazione nanoimprinting e può essere applicata a una vasta gamma di materiali e processi di deposizione.

Nanomoulding di materiali funzionali, un modello versatile complementare replica Metodo di nanoimprinting

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 Views.  Ecole Polytechnique Fédérale de Lausanne (EPFL). Descriviamo una tecnica che permette di nanomoulding basso costo patterning su scala nanometrica di materiali funzionali, pile di materiali e dispositivi completi. Nanomoulding possono essere eseguite su qualsiasi configurazione nanoimprinting e può essere applicata a una vasta gamma di materiali e processi di deposizione.

Video: 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.

Utilizzo dello scattering di incidenza di pascolo risolto neutroni Spin Echo per indagare i materiali organici delle celle solari

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.

Casting protocolli per la produzione di cellule aperte alluminio Schiume dalla tecnica di replica e l&#39;effetto sulla porosità

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.

Preparazione e reattività di gasless Nanostrutturati materiali energetici

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.

Sintesi e funzionalizzazione di 3D Materials Nano-grafene: grafene Aerogels e grafene Assemblee 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.

Metodi sperimentali avanzati per bassa temperatura magnetotrasporto Misura di nuovi materiali

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.

Metodo standardizzato per la misurazione Collection efficienza da Wipe-campionamento di esplosivi traccia

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.

Un metodo novello per<em&gt; In Situ</em&gt; Caratterizzazione elettromeccanica dei campioni di nanoscala

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.

Una fabbricazione e un metodo di misurazione per un elemento ferroelettrico flessibile basato su eteroepitassia di Van Der Waals

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.

Multiscala strutture aggregate da nanofibre impresse per superfici funzionali

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.

Studiare la risposta di Shear oscillatorio di grande ampiezza di materiali morbidi

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