Nanotechnologies for cultural heritage: nanodiamond for conservation of papers and parchments

In this paper we report some tests regarding the feasibility of nanodiamond to act as a cleaning/consolidation agent of papers and parchments. We carried out a series of treatments aiming to develop innovative approaches for de-acidification, cleaning and consolidation. Dispersions of nanodiamond have been used as de-acidification agents of ancient papers showing the ability to sensibly reduce the acidity of the paper without using any alkaline base. Similar dispersions have been used for cleaning processes and nanodiamond demonstrated an outstanding capability to clean ancient papers and parchments avoiding the use of any solvent and surfactant. Moreover interesting results were obtained by using nanodiamond as consolidation agent. In particular, artificial aging by UV exposition was appreciably contrasted when samples were preliminarily submitted to a treatment by nanodiamond. This outcome was demonstrated in papers and parchments by Raman spectroscopy analyses that evidenced the property of nanodiamond to be an excellent UV-scavenge

Nanodiamonds for Field Emission: State of the Art

The aim of this review is to highlight the recent advances and the main remaining challenges related to the issue of electron field emission (FE) from nanodiamonds. The roadmap for FE vacuum microelectronic devices envisages that nanodiamonds could become very important in a short time. The intrinsic properties of the nanodiamond materials indeed meet many of the requirements of cutting-edge technologies and further benefits can be obtained by tailored improvements of processing methodologies. The current strategies used to modulate the morphological and structural features of diamond to produce highly performing emitting systems are reported and discussed. The focus is on the current understanding of the FE process from nanodiamond-based materials and on the major concepts used to improve their performance. A short survey of non-conventional microsized cold cathodes based on nanodiamonds is also reported

Si/C hybrid nanostructures for Li-ion anodes : am overview

This review article summarizes recent and increasing efforts in the development of novel Li ion cell anode nanomaterials based on the coupling of C with Si. The rationale behind such efforts is based on the fact that the SieC coupling realizes a favourable combination of the two materials properties, such as the high lithiation capacity of Si and the mechanical and conductive properties of C, making Si/C hybrid nanomaterials the ideal candidates for innovative and improved Li-ion anodes. Together with an overview of the methodologies proposed in the last decade for material preparation, a discussion on relationship between organization at the nanoscale of the hybrid Si/C systems and battery performances is given. An emerging indication is that the enhancement of the batteries efficiency in terms of mass capacity, energy density and cycling stability, resides in the ability to arrange Si/C bi-component nanostructures in pre-defined architectures. Starting from the results obtained so far, this paper aims to indicate some emerging directions and to inspire promising routes to optimize fabrication of Si/C nanomaterials and engineering of Li-ion anodes structures. The use of Si/C hybrid nanostructures could represents a viable and effective solution to the foreseen limits of present lithium ion technology. 2013 Published by Elsevier

Effects of Au nanoparticles on photoluminescence emission from Si-vacancy in diamond

We studied the coupling of diamond Si color centers with size-controlled Au nanoparticles obtained by chemical routes. The diamond samples, synthesized by Chemical Vapor Deposition, were polycrystalline films or isolated grains. The plasmonic responses of the Au nanoparticles were found to couple with the Ar+ laser frequency or with the frequency of the Si-defects photoluminescence (PL). When the PL of Si optical centers is resonant with the maximum of the Au extinction spectrum, a threshold behavior and a decrease of the PL band FWHM with increasing laser energy is detected, suggesting the transition from spontaneous to stimulated emission

Gold nanoparticles on nanodiamond for nanophotonic applications

We present here some recent results of a research focused on the prepn. of detonation nanodiamond/Au nanoparticles hybrid materials. Two different exptl. routes are followed for the decoration of diamond nanoparticles by Au nanoparticles, that are in turn prepd. by an innovative electroless approach. Structure and morphol. at the nanoscale level of the Au-on-nanodiamond deposits have been deeply investigated by electron microscopy (FE-SEM, HR-TEM) and diffraction (XRD) techniques. Optical properties of these systems have been detd. by performing scattering and UV-Vis absorption measurements, and by comparing the exptl. data with simulated extinction spectra. The results highlighted very interesting plasmonic and scattering behaviors, mainly related to the high refractive index of diamond

Weak localization and dimensional crossover in carbon nanotube systems

We investigate the effects of magnetic and electric fields on electron wavefunction interactions in single walled carbon nanotube bundles. The magnetoresistance measurements performed at 4.2 K and the dependence of the data upon the electric field reveal good agreement with weak localization theory. An electrical field conditioned characteristic length is associated to ohmic-non ohmic transition, observed below 85 K, in current voltage characteristics. This length results equal to the average bundles diameter just at T ≅ 85 K, indicating that 2D-3D crossover is responsible for the observed conductance transition

Macroscopic Effects of Tunnelling Barriers in Aggregates of Carbon Nanotube Bundles

Abstract We report on experiments conducted on single-walled carbon nanotube bundles aligned in chains and connected through a natural contact barrier. The dependence upon the temperature of the transport properties is investigated for samples having different characteristics. Starting from two bundles separated by one barrier deposited over four-contact probes, we extend the study of the transport properties to samples formed by chains of several bundles. The systematic analysis of the properties of these aggregates shows the existence of two conduction regimes in the barrier. We show that an electrical circuit taking into account serial and parallel combinations of voltages generated at the junctions between bundles can model the samples consistently.</jats:p

CVD-based techniques for the synthesis of nanographites and nanodiamonds

We report about some Chemical Vapor Deposition approaches used to produce a variety of C-sp2 and C-sp3 crystalline nanostructures. The methodologies developed in our laboratories provide custom-made solutions for the fabrication of specific carbon nanomaterials with properties tailored for applications in the field of nanotechnology