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Authors: Frédéric Favier
Abstract: Modern resistive chemical sensors include discontinuous nano/mesostructures. Sensing performances are then governed by the chemical nature of the nanostructure gap as well as by the sensor design at the nanogap scale. Various top-down, bottom-up and hybrid fabrication routes of discontinuous/nanogaped metal nano and mesostructures have been developed. These structures are assembled/organized on insulating surfaces for integration of resistor based devices for the specific sensing of chemicals in gaseous as well as in liquid media. Hydrogen sensing based on discontinuous/gaped palladium nano/mesostructures is a chosen case-study for the evaluation of various nano/mesogap fabrication methods.
Authors: Simone Berneschi, Guillaume Alombert-Goget, Cristina Armellini, B.N.S. Bhaktha, Massimo Brenci, Andrea Chiappini, A. Chiasera, Maurizio Ferrari, Sriram Guddala, Enrico Moser, Gualtiero Nunzi Conti, Stefano Pelli, G.C. Righini, Sylvia Turrell
Abstract: The possibility to confine the light in optical planar structures represented the milestone for the development of integrated optical devices in different application areas, such as communications and sensing. In particular, rare-earth (RE) doped planar waveguides demonstrated to be an interesting solution in the realization of integrated optical lasers and amplifiers suitable for the generation/regeneration of the signal in metropolitan and local area networks. Nowadays, although these devices are commercially available, the major contribution of the research consists in discovering and developing better combinations of materials and fabrication processes, in order to reduce the costs and increase the performance of the aforesaid devices. In this context glass-ceramic waveguides, activated by RE ions, seem to fully respond to these requests. The aim of this paper is to offer a comprehensive review on the main results obtained in our Labs in the field of glassceramics. Fabrication and characterization of different silicate glass-ceramic thin films, doped with different percentages of RE ions, will be presented and discussed. The interesting results obtained make these systems quite promising for development of high performance integrated optical amplifiers and lasers.
Authors: Brigitte Boulard, Guillaume Alombert-Goget, Inna Savelii, Claire Duverger-Arfuso, You Ping Gao, Maurizio Ferrari, Francesco Prudenzano
Abstract: Er3+-doped fluoride glass ceramics planar waveguides containing LaF3 or binary LaF3- ZrF4 nanocrystals have been fabricated by Physical Vapour Deposition (PVD). A quantitative analysis of the photoluminescence for the 1.5μm emission band of Er3+ ions has demonstrated that erbium ions are partitioned in both crystals and vitreous phase; the solubility of Er3+ in the segregated LaF3 nanocrystals can reach 30 mol% and the emission bandwidth has been found to be greater than that of the precursor glass (71nm at the half-height width). In order to increase the luminescence of Er3+, codoping with Yb3+ and Ce3+ has been investigated. The high Er3+ concentration and spectral width could make this nanostructured fluoride material suitable for planar amplifier in the C telecommunication band.
Authors: Patrizia Frontera, Concetta Busacca, Vincenza Modafferi, Pierluigi Antonucci, Massimiliano Lo Faro
Abstract: . In this work PVA/Sm2O3 composite fibers and Sm2O3 fibers (PVA and Sm(NO3)3 were used as precursors) were prepared by using electrospinning technique. The fibers obtained were characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy.
Authors: Antônio Hortêncio Munhoz Jr., Renato Meneghetti Peres, L.H. Silveira, Leonardo Gondim Andrade e Silva, L.F. de Miranda
Abstract: Nanocomposites are nanometrical material particles embedded in a specific matrix. The degree of organization of the nanostructures and their properties depend on the nature of the organic and inorganic components of the structure that can generate synergic interactions. Polymeric nanocomposites are related to a class of hybrid materials where inorganic substances of nanometric dimensions are dispersed in a polymeric matrix. In the present work, nanocomposites of nylon 6,12 with different concentrations of pseudoboehmite obtained by sol-gel process were prepared with and without the presence of octadecylamine. After preparation, the samples were irradiated with a 200 kGy radiation dose in an electron accelerator. The pseudoboehmite nano particles were characterized by X-ray diffraction, scanning electron microscopy, differential thermal analysis and thermo gravimetric analysis. The nanocomposites were characterized by thermal and mechanical tests. The addition of pseudoboehmite promoted a reduction of the melting flow during the production of the composites evidencing the interaction of pseudoboehmite with the polymeric matrix, probably modifying its crystalline structure.
Authors: L. Minati, G. Speranza, I. Bernagozzi, S. Torrengo, L. Toniutti, B. Rossi, M. Ferrari, A. Chiasera
Abstract: Multi-walled carbon nanotubes were chemically cut by acid treatments and then deposited on 2-aminoethanethiol-modified gold substrate by the application of an external electric field. 2-aminoethanethiol-capped gold nanoparticles were then covalently bonded to the nanotubes to exploit their plasmon resonances. Reaction intermediates as well as the final products were analyzed by X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. The synergetic interaction between carbon nanotubes and gold nanoparticles leads to an efficient signal enhancement in Raman spectra. This is of particular interest for the detection of toxic molecules dangerous for the environment.
Authors: Valentina Domenici, Marjetka Conradi, Maja Remškar, Aleš Mrzel, Boštjan Zalar
Abstract: MoO3-x nanowires belong to photocromic materials and are promising candidates for lithium intercalation, hydrogen sensing, and smart windows. We report on a successful preparation of liquid single crystal elastomers (LSCE) containing MoO3-x nanowires, mostly the conductive Mo5O14 phase. Preparation and basic chemical and physical properties of these materials are discussed in view of the potentiality of these composites as actuators. The particular combination of molybdenum based nanowires and LSCE enables functionalization of liquid single crystal elastomers preventing the pristine mechanical and optical properties of the host matrix.
Authors: S. Torrengo, Antonio Miotello, G. Speranza, L. Minati, I. Bernagozzi, M. Ferrari, A. Chiasera, M. Dipalo, Erhard Kohn
Abstract: In the present work two different in situ amination of hydrogenated nano-crystalline diamond surfaces were studied. The effects of an UV irradiation in pure ammonia gas were compared to those produced in a mixture of pure ammonia gas with a small amount of pure oxygen. In situ XPS analysis was used to study the evolution of surface terminations from “C-H” to “CNH2”. As we will show in this work, the grafting of NH2 functional groups to the diamond surface is mediated by oxygen indicating that oxygen plays a crucial role in the process of amination.

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