•Smooth bottom and top TiO2 nanotubes were obtained with approximately 4μm length and 80nm diameter.•Ti foil surface polishing promotes an increase in open circuit voltage (Voc) and fill factor ...(FF).•Chemical polishing plus two step anodization (CP+2 step) process lead to nanotube arrays without bundles and without “nanograss”.•Dye sensitized solar cells with higher efficiency values were obtained with TiO2 nanotubes obtained on Ti foil with CP+2 step polishing.•DSSCs fabricated with nanotubes obtained with 60V for 240min (∼30μm) present higher current density indicating that recombination remains low for this length.
A study of chemical and electrochemical polishing, with and without 2 step anodization, intending to evaluate the effect of the surface roughness on TiO2 nanotube arrays formation and in dye-sensitized solar cells performance is performed.
Titanium foil substrates were chemically polished (CP) and electrochemically polished (EL) prior to the anodization process for nanotube growth. The effect of the polishing treatments on the nanotube arrays morphology was analyzed by Scanning Electron Microscopy (SEM) characterization.
Dye sensitized solar cells (DSSCs) were fabricated, with the produced nanotube arrays, and characterized intending to evaluate the effect of the Ti foil substrate surface polishing treatment on the device conversion efficiency. Photocurrent density–voltage characteristics (J–V curves) were measured under AM1 illumination at room temperature and the devices photocurrent density (Jsc), open circuit voltage (Voc), fill factor (FF), efficiency (%) and parallel resistance (RSH) values were extracted.
The best results are obtained for the chemical polishing process where nanotube arrays without bundles and without “nanograss” presence were obtained promoting higher DSSCs photocurrent density values. These results emphasize the importance of a plane and smooth titanium substrate surface for nanotubes synthesis and further device processing.
Metal oxide semiconductor (MOS) capacitors with titanium oxide (TiO
x
) dielectric layer, deposited with different oxygen partial pressure (30, 35 and 40%) and annealed at 550, 750 and 1000 °C, were ...fabricated and characterized.
Capacitance–voltage and current–voltage measurements were utilized to obtain, the effective dielectric constant, effective oxide thickness, leakage current density and interface quality. The obtained TiO
x
films present a dielectric constant varying from 40 to 170 and a leakage current density, for a gate voltage of −
1 V, as low as 1 nA/cm
2 for some of the structures, acceptable for MOS fabrication, indicating that this material is a viable high dielectric constant substitute for current ultra thin dielectric layers.
Handwritten characters in administrative antique documents from three centuries have been detected using different synchrotron X‐ray imaging techniques. Heavy elements in ancient inks, present even ...for everyday administrative manuscripts as shown by X‐ray fluorescence spectra, produce attenuation contrast. In most cases the image quality is good enough for tomography reconstruction in view of future applications to virtual page‐by‐page `reading'. When attenuation is too low, differential phase contrast imaging can reveal the characters from refractive index effects. The results are potentially important for new information harvesting strategies, for example from the huge Archivio di Stato collection, objective of the Venice Time Machine project.
We present a fundamental development step of a new technique to read and digitize ancient handwritten documents. Chemical analysis by x-ray fluorescence and x-ray tomography enabled us to decipher ...words and drawings from inside a closed, 200-pages 18th century handwritten book. The ink chemistry is essential: tomographic reading is feasible thanks to the iron present in ancient inks (iron gall) over one millennium—whereas carbon or organic inks do not provide sufficient x-ray contrast. The results presented are a key progress towards the ultimate goal of the technique: non-invasive reading of fragile and/or unopenable documents.
•X-ray tomography non-invasively “virtually reads” ancient handwritten documents•Chemical analysis of ancient inks over six centuries: iron is present, giving high x-ray contrast•Virtual reading of an unopened 200-pages 18th century handwritten book: words and other features revealed from the inside
Since 2018, a scientific research project, the “Lilybaeum Project”, is being carried out by a collaboration of physicists and archaeologists. The goal is to apply forefront analysis techniques to the ...investigation of archaeological artefacts, both in situ and in the laboratory. The first case study presented in this paper concerns the original investigation through X-ray computed tomography of a collection of objects from the Regional Archaeological Museum of Lilybaeum, in Marsala, Italy. In addition to a very significant collection of clay jars mostly from children’s graves of the ancient Lilybaeum necropolis, an unprecedented analysis of wooden planks belonging to the only existing wreck of a Punic Ship kept in the Museum is presented.
Graphene-based materials present a high surface area and can present several structural defects or heteroatoms depending on the fabrication method. Such properties facilitate the graphene interaction ...with biomolecules leading to high electrochemical activity. In this context, we synthesize a high-quality dispersed reduced graphene oxide using Lysozyme as a dispersant (Ly-RGO). In this study, we have investigated the graphite oxidation-reduction fabrication process using X-ray Photoelectron Spectroscopy, X-ray Diffraction, and Raman Spectroscopy. We have used the Ly-RGO to fabricate an electrode on an electrochemical cell in which voltammograms show significant transduction of electrical signals. Finally, cyclic voltammetry and chronoamperometry measurements were performed with human saliva and SARS-CoV-2 RNA samples, to calibrate our biosensor. The results indicate that Ly-RGO has great potential in biosensor devices.
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•Synthesis of reduced Graphene Oxide (RGO) using Lysozyme was investigated.•The presence of Lysozyme significantly increases the RGO dispersion.•RGO was used to fabricate an electrode for an electrochemical cell.•Voltammetric and chronoamperometric measurements show that the electrodes have potential application as a biosensor.•The comparison between the fabricated device and PCR tests using SARS-CoV-2 RNA reinforces that the RGO electrodes can be used as biosensors.
The diagnostic investigations are an important resource in the studies on Cultural Heritage to enhance the knowledge on execution techniques, materials and conservation status of a work of art. In ...this field, due to the great historical and artistic value of the objects, preservation is the main concern; for this reason, new technological equipment has been designed and developed in the Physics Departments of the Universities of Ferrara and Bologna to enhance the non-invasive approach to the study of pictorial artworks and other objects of cultural interest. Infrared (IR) reflectography, X-ray radiography and computed tomography (CT), applied to works of art, are joined by the same goal: to get hidden information on execution techniques and inner structure pursuing the non-invasiveness of the methods, although using different setup and physical principles. In this work transportable imaging systems to investigate large objects in museums and galleries are presented. In particular, 2D scanning devices for IR reflectography and X-ray radiography, CT systems and some applications to the Cultural Heritage are described.
In this work we report studies of the photoluminescence emission in samples based on Si/SiOx films deposited by the Pulsed Electron Beam Ablation (PEBA) technique. The samples were prepared at room ...temperature using targets with different Si/SiO2 concentrations. The samples were characterized using X-ray Absorption Edge Spectroscopy (XANES) at the Si―K edge, Raman spectroscopy, Photoluminescence (PL) and X-ray Photoelectron Spectroscopy (XPS). The concentration of a-Si and nc-Si in the film was dependent on the silicon concentration in the target. It was also observed that the PL is strongly dependent on the structural amorphous/crystalline arrangement.
► Structural analysis of SiOx films deposited by the Pulsed Electron Beam Ablation. ► This technique produces films at room temperature. ► It produced Si-rich SiOx films using targets made of Si/SiO2 powder mixtures. ► Photoluminescence was obtained as result at visible range.
Characterization of a neutron imaging setup at the INES facility Durisi, E.A.; Visca, L.; Albertin, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2013, Letnik:
726
Journal Article
Recenzirano
Odprti dostop
The Italian Neutron Experimental Station (INES) located at the ISIS pulsed neutron source (Didcot, United Kingdom) provides a thermal neutron beam mainly used for diffraction analysis. A neutron ...transmission imaging system was also developed for beam monitoring and for aligning the sample under investigation. Although the time-of-flight neutron diffraction is a consolidated technique, the neutron imaging setup is not yet completely characterized and optimized. In this paper the performance for neutron radiography and tomography at INES of two scintillator screens read out by two different commercial CCD cameras is compared in terms of linearity, signal-to-noise ratio, effective dynamic range and spatial resolution. In addition, the results of neutron radiographies and a tomography of metal alloy test structures are presented to better characterize the INES imaging capabilities of metal artifacts in the cultural heritage field.
A full characterization of the present INES imaging set-up was carried out.Two CCD cameras and two scintillators (ZnS/6LiF) of different thicknesses were tested.Linearity, effective dynamic range and spatial resolution were determined.Radiographies of steep wedges were performed using the highest dynamic range setup.Tomography of a bronze cube was performed using the best spatial resolution setup.
In this work metal/oxide/semiconductor (MOS) capacitors with different nitrogen content SiOxNy gate dielectric are fabricated and characterized. The dielectric films are deposited by the plasma ...enhanced chemical vapor deposition technique from N2, N2O and SiH4 gaseous mixtures at low temperatures. The MOS capacitors were characterized by low and high frequency capacitance (C-V) measurements, from where the interface state density (Dit), the effective charge density (Neff) and the dielectric constant (k) were extracted. The results show a dielectric constant varying linearly in function of the films nitrogen concentration, from a value of 3.9, corresponding to SiO2 to 7.2, corresponding to Si3N4. We observed a variation of Dit in function of the films nitrogen concentration, the smallest obtained value corresponding to the Si3N4 film (1X1011 cm-2eV-1), however this film presents higher leakage current density than others. In order to optimize both parameters a double dielectric layer is proposed, a first layer of Si3N4 film, which presents the highest dielectric constant and best interface properties, and a second layer of SiOxNy with high nitrogen concentration, in order to maintain the equivalent dielectric constant high but minimizing the leakage current problems.
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