Search results for "Titan"
showing 10 items of 1109 documents
CCDC 1825460: Experimental Crystal Structure Determination
2018
Related Article: Quentin Bonnin, Sook-Yen Wong, Cedric Balan, Virginie Comte, Raluca Malacea, Marie-Jose Penouilh, Philippe Richard, Gerald Kehr, Adrien T. Normand, Gerhard Erker, Pierre Le Gendre|2018|Eur.J.Inorg.Chem.|2018|3813|doi:10.1002/ejic.201800636
Diossido di titanio e alcune sue applicazioni. Spunti didattici
2016
Il diossido di titanio, TiO2, ampiamente utilizzato come pigmento di colore bianco, è uno dei materiali più studiati nell’ambito della ricerca per le sue proprietà fotocatalitiche. Esso, infatti, contribuisce alla fotodegradazione di sostanze inquinanti, motivo per cui è utilizzato nel settore della purificazione dell’aria e dell’acqua e per la realizzazione di vetri autopulenti, disponibili commercialmente. Nel presente lavoro viene suggerito un percorso didattico con l’obiettivo di mettere in evidenza le proprietà fotocatalitiche del diossido di titanio oltre che può essere utilizzato per affrontare concetti fondamentali quali la struttura a bande dei solidi e la fotocatalisi. Il percorso…
A new phase in ferroelectric oxides: The phase of charge transfer vibronic excitons
2001
It is shown, by means of Hartree-Fock-type calculations using the intermediate neglect of the differential overlap (INDO) method, that polaronic-type charge transfer vibronic excitons (CTVE) in ferroelectric oxides could lead to the formation of a new phase. The ground-state energy of this phase of strongly correlated CTVE lies within an optical gap of pure crystal, and is characterized by a strong tetragonal lattice distortion, as well as ferroelectric and antiferromagnetic ordering. It is shown also that clusters of the CTVE phase being stabilized by oxygen vacancies could be responsible for the unusually strong optical Second Harmonic Generation (SHG) in nominally pure incipient ferroele…
Theoretical study of Fe doping and oxidation–reduction influence on the photorefractive effect in BaTiO_3
1993
We numerically solve charge-transport and Poisson equations for photorefractive BaTiO3 single crystals with a band model, using four impurity levels, Fe2+–Fe3+, Fe3+–Fe4+, VO••–VO•, and VO•-VOx. Densities and photoinduced spatial distributions of each population are computed as a function of annealing O partial pressure. Space-charge field and beam-coupling gain are also computed as a function of annealing O partial pressure, temperature, Fe concentration, grating wave vector, and light intensity. We discuss the intervening mechanism of impurity centers and the correlations between experimental conditions of crystal growth, oxidation–reduction treatments, and measurement parameters.
Influence of Surface-Related Phenomena on Mechanism, Selectivity, and Conversion of TiO2 -Induced Photocatalytic Reactions
2018
Heterogeneous photocatalysis is the result of an inextricable connection of several factors differently contributing to the overall process. Photon absorption is the “sine qua non” condition for the reaction to occur. In fact, photons can be considered as immaterial reactants, and all of the phenomena related to the interaction of light–matter play a prominent role. However, other factors contribute in a concerted way to address the reaction, so that the relative contribution of each of them is often difficult to evaluate. In this framework, the present paper highlights some aspects of the interaction of TiO 2 surface-adsorbate species that could be underestimated and their influence on the…
CCDC 178473: Experimental Crystal Structure Determination
2002
Related Article: M.Horacek, P.Stepnicka, S.Gentil, K.Fejfarova, J.Kubista, N.Pirio, P.Meunier, F.Gallou, L.A.Paquette, K.Mach|2002|J.Organomet.Chem.|656|81|doi:10.1016/S0022-328X(02)01562-0
Is the re-use of sterilized implant abutments safe enough? (Implant abutment safety)
2019
Background: The reuse of implant healing abutments is common in dental practice. Effective elimination of bacteria and viruses is accomplished by conventional sterilization. The aim of this work was to explore the eventual survival of microorganisms on sterilized healing abutments and to rule out the presence of transmissible organic material after standard procedures. Material and Methods: A total of 55 healing abutments previously used in patients will be washed and sterilized in a steam autoclave at 121oC for 15 min. Each healing abutment will be cultured in Brain Heart Infusion broth (BHI) under strict aseptic conditions. Besides, two control groups will be included: one of 3 unused hea…
Application of Potassium Ion Impregnated Titanium Dioxide as Nanocatalyst for Transesterification of Linseed Oil
2018
The current work comprises the investigation of biodiesel production from linseed oil using TiO2 and a potassium L-tartrate monobasic (C4H5KO6)-modified TiO2 nanocatalyst. Different amounts of C4H5KO6 were considered for TiO2 modification. The nanocatalyst TiO2–0.5C4H5KO6 (1:0.5 molar ratio) showed the best conversion rate for biodiesel production. The nanocatalyst was characterized by FTIR, XRD, TEM, BET, and XPS, and the Hammett indicator–benzenecarboxylic acid titration method was used for basicity measurement. The biodiesel was characterized by GC-MS and 1H and 13C NMR. Furthermore, the optimum reaction parameters for transesterification reaction were analyzed, and the yield was determi…
Mechanical and metallurgical properties of titanium alloy friction stir welded butt joints
2011
Grooving by Nd:YAG laser treatment
2000
Abstract The properties of the laser beam have been used to produce deep and thin grooves in metals, melted material being removed with the assistance of a high velocity gas. Preliminary experiments show that the geometry and the location of the gas inlet tube are the main parameters governing the evacuation of the scoria. The influence of the nature of the materials on the depth of the grooves is discussed from examination of the grooves realized on various metals (copper, aluminum, titanium,…). Finally, a statistical study is performed to indicate the parameters that have to be controlled to secure regular grooves. It appears that the groove width is not too much affected by parameter var…