No abstract

International audienceThin films of amorphous alumina were fabricated using pulsed laser deposition. Topography, structural, and optical properties of alumina films were investigated depending on process parameters, specifically deposition time under vacuum and partial pressure of argon. Deposited films present good uniformity with RMS roughness ranging from 0.35 to 2.50 nm. Alumina films with thickness lower than 40 nm deposited under vacuum present a non-negligible void content that induces a decrease of the effective refractive index of the layers. Furthermore, introduction of argon gas (at 5×10−4 and 5×10−2 mbar) during the deposition process induces grainy structure of the thin films documented by an increase of RMS roughness from 0.35 to 1.5 nm. A decrease of the alumina layers’ refractive index is observed in the 300–7500 nm spectral range when increasing Ar pressur

The direct reaction of liquid (or melted solid) 1-alkanols or 1,omega-alkanediols with solid finely ground VOPO(4). 2H(2)O in a microwave field leads to layered complexes of the composition VOPO(4).2C(n)()H(2)(n)()(+1)OH (n = 1-18) or VOPO(4).C(n)()H(2)(n)()(OH)(2) (n = 2-10), respectively. The results of X-ray diffraction analysis show that the structures of all of these polycrystalline complexes (intercalates) retain the original layers of (VOPO(4))(infinity). The molecules of alcohols are placed between the host layers in a bimolecular way, being anchored to them by donor-acceptor bonds between the oxygen atom of an OH group and a vanadium atom as well as by hydrogen bonds. The molecules of diols, on the other hand, using similar bonds, form, in monomolecular arrangement, bridges linking the adjacent layers of the host. The aliphatic chains of both intercalated alcohol and diol molecules possess all-trans configurations, and their axes are perpendicular to the host layers.