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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vertikálně uspořádaná pole CdS nanotyčinek pro aplikace v solárních článcích / Vertically aligned CdS nanorod arrays for solar cell applications

Hroch, Daniel January 2016 (has links)
This thesis describes the deposition of nanoparticles into nanoporous alumina templates. Nanoparticles of cadmium sulphide were chosen thanks to wide band gap of 2,45 eV. CdS is desired semiconductor promising better efficiency when comes to solar radiation conversion to useful energy. Theoretical part consists of explanation of photovoltaic principles, band-gap theory of materials, currently available technologies to manufacture solar cells and their efficiencies. Next part introduces the approaches of manufacturing nanoporous templates from aluminium (Anodized Aluminium Oxide, AAO) in details together with options to deposit cadmium sulphide into these structures. There is also brief description of deposition based on vacuum filtration. Experiments were made in Laboratory of Microsensors and Nanotechnologies at Faculty of Electrical Engineering and Communication in Brno University of. The experimental chapter describes manufacturing process of AAO and deposition via vacuum filtration. Samples were evaluated by Scanning Electron Microscopy.
2

Mouillage et évaporation de gouttelettes de nanosuspensions / Wetting and evaporation of nanosuspension droplets

Parsa, Maryam 11 December 2017 (has links)
L’évaporation de gouttes de liquides contenant des particules non volatiles représente un phénomène largement présent dans la vie quotidienne, à l’image des traces laissées par le marc de café après séchage. L’étude de la morphologie des dépôts de particules présente un grand intérêt dans les domaines de la biologie et trouve de nombreuses applications dans l’industrie. De ce fait, elle a fait l’objet de nombreuses recherches durant les dernières décennies. Malgré les nombreuses récentes recherches sur les morphologies des dépôts de particules, les mécanismes les contrôlant restent encore non complétement expliqués. Certains facteurs influençant les morphologies des dépôts sont nombreux (température de substrats…) mais restent encore peu documentés dans la littérature. Cette étude expérimentale s’intéresse à l’influence de la température du substrat sur la morphologie des dépôts de nanoparticules après séchage de gouttes sessiles de liquides. L’augmentation de la température du substrat accélère le processus d’évaporation et entraine des morphologies de dépôts très différentes de celles obtenues sur des substrats à température ambiante. Dans cette étude, la microscopie combinée à la thermographie infrarouge et à l’interférométrie ont permis d’expliquer la dynamique de formation de dépôts. De plus, l’étude a permis d’analyser les effets d’autres paramètres sur la morphologie des dépôts, tel que la composition chimique du liquide composant les gouttes. / Evaporation of liquid droplets containing non-volatile solutes is an omnipresent phenomenon in daily life, e.g., coffee stains on solid surfaces. The study of pattern formation of the particles left after the evaporation of a sessile droplet has attracted the attention of many researchers during the past two decades due to the wide range of biological and industrial applications. Despite the significance of controlling the deposition morphology of droplets, the underlying mechanisms involved in pattern formation are not yet fully understood. There is a varied range of factors that affect the final deposition patterns and some, e.g., substrate temperature, are poorly studied in the literature. This experimental study investigates the effect of a wide range of substrate temperatures on the deposition patterns of nanoparticles from drying sessile droplets. Increasing substrate temperature and accelerating the drying process lead to the formation of the patterns not observed on non-heated substrates. This research elucidates the formation mechanisms of these patterns by optical microscopy, infrared thermography, and white light interferometry techniques. Furthermore, the combined effects of substrate temperature and other factors such as chemical composition of base fluid and particle size on the dried patterns are studied. The underlying mechanisms involved in the formation of the patterns influenced by the combined factors are also discussed and presented.

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