Superplasticity in ceramics has been the subject of intense research activity for the last two decades. Quite recently, the fabrication of fully dense nanocrystalline oxides with grain size below 100 nm enabled examination of their superplastic behaviour. This work presents a critical analysis of the plasticity of two important nanostructured oxide systems: MgO and yttria…
Tetracationic porphyrin (TMPyP) molecules were incorporated Into an optically transparent TiO2 thin film prepared by Glancing Angle Physical Vapour Deposition (GAPVD) by simple infiltration (at pH 6 4) The preparation of optically transparent TMPyP/TiO2 composite thin films provides a method for the integration of the porphyrin molecules Into photonic devices for direct monitoring of gases…
New TiO2 catalysts have been synthesised by means of a sol-gel method in which aggregates have been selected before thermal treatment. Sieving and calcination temperature have been proved to be key factors in obtaining catalysts with greater photoactivity than that of Degussa P-25. These new catalysts have been characterized by means of transmission electron microscopy…
Structure and microstructure of yttria thin films grown by electron beam physical vapour deposition on a stationary Si (111) substrate at room temperature (RT), 500 degrees and 700 degrees C, were investigated by the grazing-incidence X-ray diffraction and scanning electron microscopy, respectively. X-ray photoelectron spectroscopy provided information on the surface contamination from the atmosphere and…
A series of commercial Mg-Al hydrotalcites have been used as catalyst precursors for the methanolysis of sunflower oil.The solids were characterized by low Mg/Al molar ratios in the 0.5-2.3 range. Additionally, a solid consisting mainly of Mg(OH)(2) but containing some Al (4.2 wt.%) was also employed. The as-received materials were inactive for biodiesel synthesis so…
The effects of a high ion dose irradiation on TiO2 thin films under different conditions of temperature and ion nature are discussed. We have shown that anatase TiO2 thin films irradiated with N+ ions at room temperature develop a typical microstructure with mounds and voids open to the surface whereas irradiations at 700 K generate…
We describe a facile procedure for the synthesis at low temperature (120 A degrees C) of water-dispersible uniform YF3:Yb,Er up-conversion nanophosphors of various morphologies (rhombic and spheroidal) by homogeneous precipitation in polyol solutions containing different lanthanide salts and an ionic liquid (1-butyl, 2-methylimidazolium tetrafluoroborate) as fluoride source. It is shown that the shape of the…
This work reports an easy-to-handle method for growing two-dimensional assemblies of Ag nanostructures presenting a tunable in-plane optical anisotropy. Ag is deposited by DC sputtering in an Ar plasma at room temperature onto bundled nanocolumnar SiO2 thin films grown by glancing angle physical vapor deposition. In contrast with previously reported processes involving the grazing angle…
