Search results for "OXIDE"
showing 10 items of 6424 documents
Aggregation of [Ln(12)(III)] clusters by the dianion of 3-formylsalicylic acid. Synthesis, crystal structures, magnetic and luminescence properties
2019
Three isostrucutral dodecanuclear clusters with the general formula [Ln(12)(fsa)(12)(mu f(3)-OH)(12)(DMF)(12)]center dot nDMF (fsa(2-) is the dianion of 3-formylsalicylic acid; Ln = Eu 1, Gd 2, Dy 3) have been obtained from the reaction of fromylsalicyclic acid (H(2)fsa), tetrabutylammonium hydroxide and Ln(NO3)(3)center dot 6H(2)O in methanol/DMF. Their structure consists of four vertex-sharing heterocubanes. Each heterocubane unit is assembled from four Ln(III) ions, three mu(3)-OH groups and one mu(3)-oxygen atom arising from the fsa(2-) carboxylato group. The photophysical properties of the europium derivative investigated at both 300 and 80 K sustain a relative intense emission obtaine…
Injection and ultrafast regeneration in dye-sensitized solar cells
2014
Injection of an electron from the excited dye molecule to the semiconductor is the initial charge separation step in dye-sensitized solar cells (DSC's). Though the dynamics of the forward injection process has been widely studied, the results reported so far are controversial, especially for complete DSC's. In this work, the electron injection in titanium dioxide (TiO2) films sensitized with ruthenium bipyridyl dyes N3 and N719 was studied both in neat solvent and in a typical iodide/triiodide (I-/I3 -) DSC electrolyte. Transient absorption (TA) spectroscopy was used to monitor both the formation of the oxidized dye and the arrival of injected electrons to the conduction band of TiO2. Emiss…
Coloration mechanism of electrochromic Na x WO3 thin films
2019
International audience; The coloration mechanism of tungsten trioxide (WO3) upon insertion of alkali ions is still under debate after several decades of research. This Letter provides new insights into the reversible insertion and coloration mechanisms of Na+ ions in WO3 thin films sputter-deposited on ITO/glass substrates. A unique model based on a constrained spline approach was developed and applied to draw out ε1+iε2 from spectroscopic ellipsometry data from 0.6 to 4.8 eV whatever the state of the electrochromic active layer, i.e. as-deposited, colored or bleached. It is shown that electrochemically intercalated sodium-tungsten trioxide, NaxWO3 (x=0.1, 0.2, 0.35), exhibits an absorption…
Long-term evolution of luminescent properties in CdI2 crystals
2016
Fresh and aged melt-grown or gas-phase grown CdI2 crystals are studied by means of low-temperature photoluminescence spectroscopy. Noticeable transformations of emission spectra are observed after long-term aging. The formation of nanostructures containing cadmium oxide and cadmium hydroxide as well as the changes in local surrounding of iodine atoms and the possible growth of polytypic modifications of CdI2 are taken into account when considering the diversity of optical spectra.
High‐Quality Si‐Doped β‐Ga 2 O 3 Films on Sapphire Fabricated by Pulsed Laser Deposition
2020
The EU Horizon 2020 project CAMART2 is acknowledged for partly supporting the project, and the Ion Technology Centre, ITC, in Sweden is acknowledged for ion beam analysis (ERDA).
Silicon Surface Passivation by ALD-Ga2O3: Thermal vs. Plasma-Enhanced Atomic Layer Deposition
2020
Silicon surface passivation by gallium oxide (Ga2O3) thin films deposited by thermal- and plasma-enhanced atomic layer deposition (ALD) over a broad temperature range from 75 °C to 350 °C is investigated. In addition, the role of oxidant (O3 or O-plasma) pulse lengths insufficient for saturated ALD-growth is studied. The material properties are analyzed including the quantification of the incorporated hydrogen. We find that oxidant dose pulses insufficient for saturation provide for both ALD methods generally better surface passivation. Furthermore, different Si surface pretreatments are compared (HF-last, chemically grown oxide, and thermal tunnel oxide). In contrast to previous reports, t…
Atomic Layer Deposition and Properties of Lanthanum Oxide and Lanthanum-Aluminum Oxide Films
2006
Atomic layer deposition (ALD) of lanthanum oxide on glass and silicon substrates was examined using lanthanum silylamide, La[N(SiMe 3 ) 2 ] 3 , and water as precursors in the substrate temperature range of 150-250 °C. The effect of pulse times and precursor evaporation temperature on the growth rate and refractive index was investigated. The films remained amorphous regardless of the deposition conditions. The resulting La 2 O 3 films contained noticeable amounts of hydrogen and silicon and were chemically unstable while stored in ambient air. Lanthanum aluminum oxide films were achieved with stoichiometry close to that of LaAlO 3 at 225°C from La[N(SiMe 3 ) 2 ] 3 , Al(CH 3 ) 3 , and H 2 O.…
Spark Plasma Sintering à partir de poudres mécaniquement activées : compréhension des transitions de phase au cours d'un frittage réactif
2007
International audience; À " basse température " (entre 400 et 600 ◦C), l'oxydation de MoSi2 entraîne sa désintégration en poudre (phénomène de " peste "). De récents travaux ont montré que l'utilisation de MoSi2 dense et nano-organisé permettrait de ralentir ce phénomène de " peste ". Le défi de produire des matériaux denses et nano-organisés peut être relevé par le frittage " flash " réactif sous champ électrique à partir des poudres mécaniquement activées (Mechanically-Activated Spark Plasma Sintering, MASPS). Le contrôle de la composition et de la microstructure du composé intermétallique MoSi2 nécessite de déterminer les paramètres du frittage SPS (température, rampe de montée en tempér…
Electrical transport in lead-free (Na0.5Bi0.5)1–xSrxTiO3 ceramics (x = 0, 0.01 and 0.02)
2017
Lead-free (Na0.5Bi0.5)1xSrxTiO3 (x = 0, 0.01 and 0.02) ceramics were manufactured through a solid-state mixed oxide method and their ac (σac) and dc (σdc) electric conductivity were studied. It is ...
Ab Initio Modeling of Y and O Solute Atom Interaction in Small Clusters within the bcc Iron Lattice
2018
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euroatom research and training programme 2014–2018 under grant agreement No 633053. The authors are indebted to A. Möslang and P. V. Vladimirov for stimulating discussions. The views and opinions expressed herein do not necessarily reflect those of the European Commission.