Search results for "Metallurgy"
showing 10 items of 1419 documents
Cr- and Sb-containing TiO 2 inorganic orange nano-pigments prepared by a relative long hydrocarbon chain polyol
2016
Abstract We report the preparation of a series of orange Cr- and Sb-containing TiO 2 nano-pigments by the polyol via using triethylenglycol (TEG). Poorly crystallized anatase nanopowders with nominal stoichiometric compositions Cr x Sb x Ti 1−2x O 2 , with 0 ≤ x ≤ 0.2, were obtained by heating at 180 °C a solution of antimony acetate, chromium acetylacetone and titanium butoxide in TEG. The transition temperature of the chromium- and antimonium-containing anatase nanoparticles into the rutile crystalline form occurred over the range of temperature between 500 and 650 °C, depending on the dopant amount. After annealing at 800 °C for short time the series of samples displaying the rutile stru…
Study of the structural changes induced by air oxidation in Ti–Si–N hard coatings.
2008
International audience; 3-μm thick Ti–Si–N coatings were deposited on polished X38CrMoV5 substrates by sputtering a composite Ti–Si target in Ar–N2 reactive mixture. Oxidation tests were performed in air at 700 °C during 2 h. Whatever the silicon content in the range 0–4 at.%, no silicon containing compound was detected by XRD before air oxidation and only the TiN phase was evidenced. The mean grain size estimated from the full width at half maximum of the TiN (111) diffraction peak was close to 10 nm. As commonly reported for Ti–Si–N films, the hardness showed a maximum at 51 GPa versus the Si content. After oxidation of the TiN film, XRD and micro-Raman analyses revealed the occurrence of…
Study of phase composition, photocatalytic activity, and photoluminescence of TiO2 with Eu additive produced by the extraction-pyrolytic method
2021
The Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2. The work was also partially supported by the LZP grant 2020/2-0074. R. Burve has been supported by the project “Synthesis of nanostructured materials based on titanium dioxide and tin dioxide and investigation of their physicochemical properties” Nr. MP-2019/7, for strengthening scientific personnel capacity 2019/2020 at the Riga Technical University. Authors are grateful to Dr. K. Šmits for the microscopic measurements and SEM images.
Preparation and photoactivity of electrophoretic TiO2coating film
2012
TiO2 thin films have been obtained by a sol-electrophoretic deposition method on metallic Ti and Pt substrates. X-ray diffraction, Raman spectroscopy and scanning electron microscopy were used to investigate the structure and morphology of plated materials. Annealed TiO2 films mainly are formed in anatase structure with different morphology depending on substrate material. Light induced potential measurements indicate that the morphology substantially have an impact on photoactivity of TiO2 thin films.
Homogeneous Langmuir-Blodgett Film of Double-Chain Ammonium Amphiphile Complexed with Anionic Polymer
1988
Heterogeneous textures suggesting the coexistence of a fluid and a solid phase were found both in a surface monolayer and in a deposited Langmuir-Blodgett (LB) film of double-chain ammonium amphiphiles by fluorescence microscopy. Although an annealing of the surface monolayer at 40°C allowed crystal growth, the heterogeneous phase separation remained in the LB film. A drastic change of the fluorescence image shows that the recrystallization of the complexed monolayer with anionic polymers conducted the homogeneous monolayer.
Annealing of radiation induced oxygen deficient point defects in amorphous silicon dioxide: evidence for a distribution of the reaction activation en…
2011
The selective annealing of point defects with different activation energies is studied, by performing sequences of thermal treatments on gamma irradiated silica samples in the temperature range 300-450 °C. Our experiments show that the dependence on time of the concentration of two irradiation induced point defects in silica, named ODC(II) (standing for oxygen deficient centre II) and the E(γ)(') centre, at a given temperature depends on the thermal history of the sample for both of the centres studied; moreover in the long time limit this concentration reaches an asymptotic value that depends on the treatment temperature alone. These results suggest the existence of a distribution of the a…
Transient and stable color centers in pure and Cu-doped LiNbO3
2003
The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO 3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.
Watching adsorption and electron beam induced decomposition on the model system Mo(CO)(6)/Cu(111) by X-ray absorption and photoemission spectroscopies
2013
Abstract An in-depth study of the first steps of electron beam assisted growth of Mo from molybdenum hexacarbonyl on Cu(1 1 1) has been carried out exploiting the complementarity of X-ray photoemission and X-ray absorption spectroscopies. Frank van der Merwe (2D) growth mode has been observed for the completion of the two first monolayers of adsorbed molecules through a simple physisorption process. Irradiation of the Mo(CO)6 deposit by 1 keV electron beam induces a modification of molybdenum coordination, the average number of C-neighbors decreasing from 6 to 3. Decomposed molecules remain on the surface after annealing at 520 K and organize themselves, the molybdenum atoms moving in Cu(1 …
"Reactivity of Cu3Si of different genesis towards copper(I) chloride"
2000
Abstract A comparative study of the reactivity between copper(I) chloride and three types of Cu 3 Si obtained in a molten medium (Cu 3 Si-Ref) and from mechanical activation following an annealing process (Cu 3 Si-M2AP) or a self-propagating high-temperature synthesis (Cu 3 Si-MASHS) was performed by thermogravimetry under vacuum using non-isothermal and isothermal methods of kinetic measurement. It was established that for the three Cu 3 Si/CuCl systems, the acceleration and decay stages in the temperature range 145–215°C are very closely approximated by an equation of the Prout–Tompkins type where an autocatalytic process was proposed. The lower apparent activation energy obtained for the…
Should TiO2 nanostructures doped with Li+ be used as photoanodes for photoelectrochemical water splitting applications?
2017
[EN] Different TiO2 nanostructures, nanotubes and nanosponges, were obtained by anodization of Ti under stagnant and hydrodynamic conditions. Samples were doped with Li+ before and after annealing at 450 degrees C during 1 h. The nanostructures were characterized by different microscopy techniques: Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Confocal Laser Microscopy. Additionally, Incident Photon-to-electron Conversion Efficiency (IPCE), photoelectrochemical water splitting and stability measurements were also performed. According to the results, TiO2 nanostructures doped before annealing present the worst photocurrent response, even if compared with undoped samples. On …