Search results for "Titanium isopropoxide"
showing 10 items of 13 documents
Enantioselective Addition of Dimethylzinc to Aldehydes Catalyzed by N-Substituted Mandelamide-Ti(IV) Complexes.
2005
Abstract Amides derived from ( S )-(+)-mandelic acid in the presence of titanium isopropoxide catalyze the enantioselective addition of dimethylzinc to aromatic aldehydes with good yields and ee up to 90%.
Amorphous TiO2 in LP-OMCVD TiNxOy thin films revealed by XPS
2001
Abstract TiN(O)–TiO 2 thin films were prepared on Si(1 0 0) by the low pressure organo metallic chemical vapor deposition (LP-OMCVD) method, using ammonia and titanium isopropoxide as precursors. In order to complete previous characterizations, an Ar + bombardment/XPS coupled study was carried out. This method is based on the fact that the behavior of a compound towards an ion bombardment is a function of its composition. In particular, Ar + bombardment of TiO 2 (whatever its form) leads to a preferential sputtering of oxygen atoms with subsequent reduction of titanium and formation of Ti 3+ and Ti 2+ easily detectable by XPS from a significant broadening of the Ti 2p lines. In the opposite…
Nanostructured Pt–TiO2 composite thin films obtained by direct liquid injection metal organic chemical vapor deposition: Control of chemical state by…
2015
Abstract Nanostructured Pt–TiO 2 composite thin films were synthesized by direct liquid injection metal organic chemical vapor deposition process, using trimethyl(methylcyclopentadienyl)platinum and titanium isopropoxide as precursors. Surface and cross-sectional morphologies obtained by scanning electron microscopy and transmission electron microscopy evidenced the uniform distribution of platinum nanoparticles in the TiO 2 matrix. At higher Pt content, the X-ray diffraction analysis showed that the face-centered cubic phase of platinum appeared together with an anatase TiO 2 structure. In addition, as far as the platinum chemical state is concerned, the co-deposition of TiO 2 and Pt allow…
Stamping of monomeric SAMs as a route to structured crystallization templates: patterned titania films.
2000
Gold-coated glass slides have be patterned by using self-assembled monolayers (SAM) of alkane thiols. Through the use of a special thiol terminated with a styrene monomer, microstructures of 5 to 10 microm width and 70 A height have been formed on the surface by graft polymerization of styrene. These patterned gold slides have then been used to template the precipitation of thin titania films from ethanolic solutions of titanium isopropoxide to create microstructured architectures in the film. Plasmon resonance spectra have established the presence of different steps in the process and have been used to follow the kinetics of the precipitation of titania on the surface. The structured TiO2 …
Conductimetry and impedance spectroscopy study of low pressure metal organic chemical vapor deposition TiN O films as a function of the growth temper…
2001
Abstract Titanium oxinitride thin films have been grown by low pressure metal organic chemical vapor deposition (LP-MOCVD) using titanium isopropoxide, Ti(OCH(CH 3 ) 2 ) 4 (TIP) and NH 3 precursors in a growth temperature range from 450 to 750°C on sapphire substrates. The electrical behaviour of these films was studied between 400 and 173 K, revealing three different behaviours, ranking from a hopping conductivity (450–500°C) to a conducting one (700–750°C), with a dual behaviour for the intermediate growth temperatures. Moreover, at room temperature, both conductimetry and impedance spectroscopy highlighted a percolation behaviour, interpreted in terms of continuum percolation. The effect…
SEM and XPS studies of titanium dioxide thin films grown by MOCVD
1998
Abstract The metal organic chemical vapour deposition (MOCVD) method was used to prepare titanium dioxide thin films. Thin films of TiO2, about 100 nm thick, were deposited on (100)Si and (1102)Al2O3 sapphire substrates using titanium isopropoxide (Ti(OC3H7)4) as metal organic precursor. The morphology of the films and the presence of impurities on the thin films surfaces were studied using respectively, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The influence of the growth parameters such as the deposition temperature, the carrier gas (nitrogen) flow rate and the presence of an additional oxygen flow on the characteristics of the titanium dioxide films h…
Low-temperature Ti-containing 3:2 and 2:1 mullite nanocrystals from single-phase gels
2007
Abstract TiO 2 -containig single-phase gels with (Al 2 O 3 + TiO 2 )/(SiO 2 ) molar ratios 3/2 and 2/1 were prepared by gelling mixtures of aluminium nitrate, tetraethylorthosilicate and titanium isopropoxide. Gels were fast heated at several temperatures up to 1100 °C. Dried and heated gels were characterized by differential thermal analysis (DTA), magic angle spinning nuclear magnetic resonance (MAS-NMR), X-ray powder diffraction (XRD), and scanning and transmission electron microscopies (SEM and TEM). Coupled DTA and XRD results of gels fast heated at 900 °C showed the crystallisation of two mullites as well as a small amount of alumina-silica spinel. 27 Al NMR spectra showed the format…
Thermal stability of Au–TiO2 nanocomposite films prepared by direct liquid injection CVD
2015
Abstract Nanocomposite films composed of gold nanoparticles (AuNPs) embedded in a TiO 2 matrix have been prepared by direct liquid injection chemical vapor deposition process, using preformed nanoparticles and titanium isopropoxide as precursors. The spherical AuNPs about 4.1 nm in diameter were synthesized by using gold (III) chloride trihydrate and stabilized by thiol ligands. The depositions were carried out by performing at first oxide deposition, then gold nanoparticle one and capping with oxide. The morphology, structure; the chemical state and optical properties of nanocomposite films were characterized by scanning electron microscopy, Raman, X-ray photoelectron and UV–Vis absorption…
Correlation Between the Electrical Properties and the Morphology of Low-Pressure MOCVD Titanium Oxynitride Thin Films Grown at Various Temperatures
2000
Titanium oxynitride (TiN x O y ) thin films were deposited by low-pressure metal-organic CVD (LP-MOCVD) on (100) silicon, sapphire, and polycrystalline alumina substrates. Titanium isopropoxide (TIP) and ammonia were used as precursors. The influence of the growth temperature, ranking from 450°C to 750°C, was investigated by scanning electron microscopy (SEM), and electrical DC measurements. Rutherford back-scattering (RBS) measurements were used to determine the N/O ratio in the films. The surface observations of the deposited films showed two morphological transitions. The resistivity decreased with the growth temperature, while the nitrogen content increased. Moreover, for the highest de…
Influence of sol counter-ions on the visible light induced photocatalytic behaviour of TiO2 nanoparticles
2014
Titanium dioxide (TiO2) nanoparticles are attracting increasing interest because of their superior photocatalytic and antibacterial properties. Here, aqueous titanium oxy-hydroxide sols were made, using a green synthesis method, from the controlled hydrolysis/peptisation of titanium isopropoxide. Three different mineral acids were used to peptise the sol (HNO3, HBr and HCl), and provide counter-ions. The influence of nitrate or halide sol counter-ions on size distributions of the starting sols were measured via photon correlation spectroscopy (PCS). Semi-quantitative phase composition analysis (QPA), on the gels thermally treated at 450 and 600 degrees C, was carried out via Rietveld refine…