Carbon Nanotubes (CNTs) are used extensively in various applications where substrate are required to be possessing higher surface area, porosity and electrical and thermal conductivity. Such properties can be enhanced to target a particular gas and biochemical for efficient detection when CNT matrix is functionalized with Nanoparticles (NPs). Conventional functionalization involves harsh oxidation repeated washing, filtration and sonication, which induce defects. The defects lead to hindered mobility of carriers, unwanted doping and also fragmentation of the CNTs in some cases. In this document we demonstrate functionalization of CNT with Au nanoparticles on a macro scale under dry and ambient condition using Xenon ash induced solid-state dewetting. A sputtered thin film was transformed into nanoparticles which were confirmed to be in a state of thermodynamic equilibrium. We worked on 3 nm, 6 nm, 9 nm, 15 nm, 30 nm initial thickness of thin films. Xenon ash parameters of energy, number of pulse, duration of pulse, duration of gap between consecutive pulses were optimized to achieve complete dewetting of Au thin films. 3 nm deposition was in the form of irregular nano-islands which were transformed into stable nanoparticles with a single shot of 10 J/cm2 of 2 ms duration. 6 nm and 9 nm deposition was in form of continues film which was also dewetted into stable nanoparticles with a single pulse but with an increased energy density of 20 J/cm2 and 35 J/cm2 respectively. In case of 15 nm and 30 nm deposition the thin film couldn't be dewetted with a maximum energy density of 50 J/cm2, it was observed that 3 and 4 pulses of 2 ms pulse duration and 2 ms gap duration with an energy density of 50 J/cm2 were required to completely dewet the thicker films. However irregularity was induced in the sizes of the NPs due to Ostwald ripening phenomenon which causes smaller particle within a critical difiusion length to combine and form a larger particle during or after dewetting process. For comparison, the Au thin films were also dewetted by a conventional process involving annealing of samples until the thin film was fully transformed into NPs and the size of NPs seized to grow. Scanning electron microscope (SEM) was used to characterize the samples. Thermodynamic stability of the particles was confirmed with statistical analyses of size distribution after every additional pulse.

Les couches minces d’argent sont largement employées dans l’industrie verrière à des fins d’isolation ; leur instabilité est un problème critique. Les travaux ont porté sur l’étude du démouillage (i.e. agglomération) de couches minces d’argent sur de la silice amorphe, selon deux axes : la compréhension du mécanisme par l’emploi de méthodes in situ et le contrôle du démouillage induit par une texturation du substrat à l’échelle nanométrique. Les différentes techniques de microscopie in situ ont permis de mettre en évidence le rôle particulier joué par certains grains lors du démouillage. Celui-ci se déroule en trois étapes distinctes : l’induction, la propagation, et le frittage. Les grains qui donnent lieu à des particules à la fin du démouillage sont identifiables durant toutes ces étapes. Le démouillage est fortement influencé par la présence d’oxygène dans l’atmosphère de recuit. En présence d’oxygène, certains grains très spécifiques accumulent la matière provenant du démouillage. En absence d’oxygène, l’argent se répartit sur davantage de grains, les trous adoptent une forme dendritique. Une analyse d’image a permis de montrer que le modèle capillaire usuellement employé dans la littérature ne permettait pas de décrire l’évolution constatée. Un nouveau modèle, fondé sur le rôle individuel des grains, a été proposé. Le démouillage sur des surfaces texturées permet d’obtenir des rangées de particules nanométriques organisées. Une méthode a été développée afin de minimiser les défauts intrinsèques à la méthode. Des mesures optiques effectuées sur ces échantillons ont mis en évidence une modification de l’absorption due à l’organisation spatiale des particules. / Silver thin films are widely used in the glass industry for their insulation properties. Their stability is crucial. This work focus on silver solid-state dewetting (i.e. agglomeration) on amorphous silica substrates, divided into two axes: understanding the mechanisms thanks to in situ experiments and controlling the dewetting thanks to the patterning of the substrate at the nanoscale. The various in situ microscopy techniques revealed the role of specific grains in the dewetting mechanism. Dewetting proceeds into three steps: induction, propagation and sintering. Throughout these steps, the grains that eventually give birth to particles are identified, even as early as induction. Dewetting is strongly impacted by the oxygen content of the annealing atmosphere. When present, oxygen promotes the growth of very specific grains, where all dewetted material agglomerates. Without oxygen, silver is distributed on a larger number of grains, surrounding the holes that take a dendritic shape. A cautious image processing procedure allowed us to conclude that the capillary models usually invoked were not suitable for our system. A new model, based on the role of individual grains, is suggested. Dewetting on patterned substrates is a way to produce large arrays of organised nanoparticles. A method was developed to minimize in these arrays the number of defects inherent to dewetting. Optical measurements on such arrays showed that the spatial organisation of the particles led to a specific signature in optical absorption.

Magnetické nanočástice a nanostrukturované materiály jsou velkým příslibem v mnoha oblastech, včetně biomedicíny, sanace životního prostředí nebo získávání energie. Proto neustále roste zájem o výzkum jejich jedinečných vlastností a vývoj uskutečnitelných výrobních postupů. Tato práce se zabývá metodou samouspořádávání, spočívající v povrchové precipitaci tenkých vrstev, za účelem výroby epitaxních polí nanoostrůvků ze slitiny FeRh na různých monokrystalických substrátech. Při tomto výrobním postupu zůstává zachována metamagnetická fázová přeměna nanoostrůvků. Morfologie a magnetické vlastnosti samouspořádaných nanomagnetů z FeRh jsou charakterizovány kombinací experimentálních technik a modelování, přičemž bylo zjištěno, že jejich rovnovážné tvary a magnetické uspořádání jsou navzájem propojeny. Kromě toho je navržena cesta pro získání volných nanočástic, která by mohla potenciálně umožnit využití metamagnetických nanostruktur v buněčných kulturách a biomedicíně obecně. Za tímto účelem jsou nanoostrůvky FeRh uvolňovány ze substrátu chemickým leptáním. Chování nanočástic a jejich reakce na teplotu a magnetické pole jsou studovány v kapalném prostředí. Metamagnetické vlastnosti separovaných nanočástic jsou charakterizovány pomocí vibrační magnetometrie.