1,721,194 research outputs found
Pulsed Laser Deposition of Nanostructured Oxides: from Clusters to Functional Films
No full textNanosecond Pulsed Laser Deposition (PLD) in a background atmosphere is a particularly versatile technique for the production of nanostructured films and surfaces. The ablation plasma plume produced by laser-matter interaction is spatially confined by the presence of a background gas, thus favouring cluster nucleation and reduction of the kinetic energy of the species impinging the substrate. This affects deposition processes and film growth mechanisms leading to the production of nanostructured systems.
Here we review our recent work focused on the development of the PLD technique for the controlled synthesis of nanostructured materials, films and surfaces with tailored properties. We show in particular that by playing with the plasma expansion dynamics, through the control of background gas type and pressure and target-to-substrate distance, a fine tuning of morphology, structure and composition can be reached for a number of metal oxides (e.g. tungsten, titanium and silver oxide). Film morphology can be varied from compact to columnar and nanostructured up to highly porous foam-like with corresponding reduction of mass density and increase of surface area. Oxide formation and stoichiometry can be controlled by ablating metal targets in a reactive background gas atmosphere. Film structure can be varied from amorphous to nanocrystalline while different oxide phases can be obtained by post-deposition thermal treatments, also depending on the starting morphology. The first stages of film growth and their relation with the size and the deposition kinetic energy of the building blocks have been investigated by in situ scanning tunnelling microscopy (STM)
Pulsed Laser Deposition of Nanostructured Oxides for Emerging Applications
No full textMetal oxides are presently employed in a number of advanced technological applications ranging from sensing, biology and energy. For such applications a good control of material properties ranging from morphological and structural to functional ones is required in order to improve or enhance the performances of the systems and the related devices. We here review our work on the Pulsed Laser Deposition of nanostructured films and surfaces showing that a fine tuning of morphology and structure can be achieved for metal oxides such as tungsten and titanium oxide. Starting from the control of the building units constituting the material we show that film morphology can be varied from compact to columnar and nanostructured to a hierarchical assembly of nanoparticles and finally to highly porous foam-like. Film structure can be varied from amorphous to nanocrystalline with the possibility to vary the oxide phase. Finally we will discuss possible applications showing that such oxides have good performances as functional materials
Bottom-up synthesis of nanostructured materials by Pulsed Laser Deposition: from clusters to functional films
No full textCD conference proceeding
Carbon-atom wires produced by nanosecond pulsed laser deposition in a background gas
Full text linkWires of sp-hybridized carbon atoms are attracting interest for both fundamental aspects of carbon
science and for their appealing functional properties. The synthesis by physical vapor deposition has
been reported to provide sp-rich carbon films but still needs to be further developed and understood in
detail. Here the synthesis of carbon-atom wires (CAWs) has been achieved by nanosecond pulsed laser
deposition (PLD) expoliting the strong out-of-equilibrium conditions occurring when the ablation
plasma is confined in a background gas. Surface Enhanced Raman Spectroscopy (SERS) spectra of
deposited films indicate that CAWs are mixed with a mainly sp2 amorphous carbon in a sp-sp2 hybrid
material. Optimal conditions for the deposition of sp-carbon phase have been investigated by changing
deposition parameters thus suggesting basic mechanisms of carbon wires formation. Our proof-ofconcept
may open new perspectives for the targeted fabrication of CAWs and sp-sp2 structures
Pulsed laser deposition of nanostructured metals and oxides: from cluster assembling to applications
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