Search results for "Titanium"
showing 10 items of 878 documents
Photo-electrochemical and impedance investigation of passive layers grown anodically on titanium alloys
2004
Abstract The anodic behaviour of two titanium cast alloys, obtained by fusion in a voltaic arc under argon atmosphere, was analyzed in aerated aqueous solutions having different pH values. In all solutions the alloys, having nominal compositions Ti–50Zr at.% and Ti–13Zr–13Nb wt.%, displayed a valve-metal behaviour, owing to the formation of barrier-type oxide films. Passive films, grown potentiodynamically up to about 9 V, were investigated by photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). These passive layers show photoactivity under anodic polarizations, with optical gaps close to 3.55 and 3.25 eV for the binary and the ternary alloy, respectively, indep…
Influence of the crystallization process on the photoelectrochemical behaviour of anodic TiO2 films
1997
On the basis of kinetic and photoelectrochemical studies we show that the formation of amorphous or strongly disordered TiO2 films on electropolished titanium rods can occur upon anodization in 0.5 M H2SO4 solution in a range of thickness which depends on the anodization rate. This finding is confirmed both by the changes in the shape of the photocurrent vs. potential curves with the energy of the incident photons, and by the impedance behaviour of the junction. Our data indicate that TiO2 films having different degree of disorder are formed depending on the anodization rate and oxide thickness. Crystalline films are formed at very low growth rates since very low thicknesses. Amorphous or s…
Titanium dioxide surface stoichiometry and ordering studied by resonant photoemission spectroscopy
2005
Abstract The electronic structure of titanium dioxide surfaces having undergone different preparations leading to different stoichiometries and crystallinities has been studied using resonant photoemission spectroscopy. Valence band photoemission spectra through the Ti 3p–3d/4s absorption edge between 45 and 55 eV were measured and allowed a characterization of defects present at the surface as well as of the quality of the surface organization. Indeed, from the comparison of the resonance results obtained for each kind of surface with the LEED patterns on the one hand and the corresponding Ti 2p core level lines on the other hand, it was evidenced that the high binding energy part of the v…
Spontaneous oxygen loading into SiO2 glass by thermal anneal
2004
The interstitial oxygen molecules (O 2 ) in SiO 2 glass were detected down to ∼10 15 cm -3 by photoluminescence of O 2 at 1272nm excited at 765nm by a continuous-wave titanium sapphire laser. It was evidenced that SiO 2 glass thermally annealed in air between 800 and 1100°C spontaneously absorbs ∼10 16 cm -3 of O 2 from the ambient atmosphere. The time-dependent concentration change of the interstitial O 2 allows the determination of both the diffusion coefficient and the solubility of the interstitial O 2 .
Alpha spectrometric characterization of thin $^{233}$U sources for $^{229\text{(m)}}$Th production
2020
Four different techniques were applied for the production of $^{233}$U alpha recoil ion sources, providing $^{229}$Th ions. They were compared with respect to a minimum energy spread of the $^{229}$Th recoil ions, using the emitted alpha particles as an indicator. The techniques of Molecular Plating, Drop-on-Demand inkjet printing, chelation from dilute nitric acid solution on chemically functionalized silicon surfaces, and self-adsorption on passivated titanium surfaces were used. All fabricated sources were characterized by using alpha spectrometry, radiographic imaging, and scanning electron microscopy. A direct validation for the estimated recoil ion rate was obtained by collecting $^{2…
Valutazione in vitro dell’affaticamento di strumenti rotanti in nichel-titanio
2012
Riassunto Obiettivo L’obiettivo di questo lavoro e quello di valutare, in vitro, la fatica ciclica di ProFile, K3 e Twisted File, strumenti rotanti in nichel-titanio, in canali radicolari simulati aventi angoli di curvatura di 45°, 60° e 90°. Materiali e metodi Per effettuare questo studio sono stati utilizzati: 18 file 25/.06 ProFile; 18 file 25/.06 K3; 18 file 25/.06 Twisted File. La resistenza a fatica ciclica degli strumenti rotanti Ni-Ti e stata testata ad angolazioni di 45°, 60° e 90° mediante un modello sperimentale creato specificatamente. Risultati e conclusioni Dall’analisi dei dati e emersa una buona resistenza alla fatica ciclica per quanto concerne le sistematiche ProFile e Twi…
Backings and targets for chemical and nuclear studies of transactinides with TASCA
2008
Abstract At GSI the gas-filled separator TASCA (TransActinide Separator and Chemistry Apparatus) was set up to investigate the chemical and physical properties of the heaviest elements making use of the highest beam intensities available [ www.gsi.de/tasca ; M. Schadel, D. Ackermann, A. Semchenkov, A. Turler, GSI Scientific Report 2005, GSI Report 2006-1, p. 262]. Appropriate backings and targets have to be developed. Conceivable backing materials are aluminium, titanium, and carbon. Aluminium backings and titanium backings in different thickness and from different companies are produced by cold rolling. Deposition by resistance heating is applied for carbon backings. For experiments in a c…
Characterization of deuteride titanium targets used in neutron generators
2000
Abstract The study of the physicochemical characteristics of titanium thin films and the corresponding deuterium absorption/desorption kinetics was performed. In order to optimize the production of high-energy neutrons the behaviour of deuteride titanium targets has been studied experimentally by bombardment with 120 and 350 kV deuterons by means of electrostatic accelerators. The importance of the deposit evaporation conditions on the efficiency of neutron emission is clearly demonstrated as well as the thermomechanical stability of the Ti thin film by deuteron bombardment. The main parameters involved in the targets behaviour have been discussed from a thermodynamical approach.
Development and characterization of a Drop-on-Demand inkjet printing system for nuclear target fabrication
2017
Abstract A novel target preparation method based on Drop-on-Demand (DoD) inkjet printing has been developed. Conventional preparation methods like the electrochemical method “Molecular Plating” or the “Polymer-Assisted Deposition Method” are often limited, e.g., concerning the dimensions and geometries of depositions or by the requirement for electrically conducting substrates. Here, we report on the development of a new technique, which overcomes such limits by using a commercially available DoD dispenser. A variety of solutions with volumes down to 5 nL can be dispensed onto every manageable substrate. The dispensed volumes were determined with a radioactive tracer and the deposits of eva…
Investigation of the (d, p)-reaction on136, 132Xe in inverse kinematics
1991
The one-neutron transfer reactions d(132,136 Xe, p)133,137 Xe have been investigated in inverse kinematics with xenon beams incident on deuterium loaded titanium targets. The angular distributions of the protons, measured with a detector array of 100 PIN-photodiodes, have been analyzed using standard DWBA. Generally, good agreement is obtained with results previously obtained in reactions induced by light-ion beams.