Preparation of metal-ceramic composites by sonochemical synthesis of metallic nano-particles and in-situ decoration on ceramic powders.

Copper and nickel nanoparticles were synthesized using reducing agents in the presence of direct high energy ultra-sonication. The metallic nanoparticles were decorated on various ceramic substrates (e.g. α-Al2O3, and TiO2) leading to metal reinforced ceramics with up to 45% metallic content. Different parameters, such as the amount of precursor material or the substrate, as well as the intensity of ultrasound were examined, in order to evaluate the percentage of final metallic decoration on the composite materials. All products were characterized by means of Inductively Coupled Plasma Spectroscopy in order to investigate the loading with metallic particles. X-ray Diffraction and Scanning Electron Microscopy were also used for further sample characterization. Selected samples were examined using Transmission Electron Microscopy, while finally, some of the powders synthesized, were densified by means of Spark Plasma Sintering, followed by a SEM/EDX examination and an estimation of their porosity.

Oxygen incorporation into strontium titanate single crystals from CO(2) dissociation.

Oxygen incorporation from CO(2) into Fe-doped SrTiO(3)(100) single crystals (0.013 at% Fe, 0.039 at% Fe and 0.13 at% Fe) was investigated. Oxygen incorporation processes using (13)C(18)O(2) as the gas source were studied by isotope exchange depth profiling (IEDP) and subsequent secondary-ion mass spectroscopy (SIMS). The interaction of CO(2) with SrTiO(3) (100) surfaces was further studied with different surface analytical techniques like metastable induced electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Results indicate that CO(2) interaction with SrTiO(3) (100) surfaces does not change the surface at all. It seems that CO(2) provides a very low sticking probability on the surface as it is not traced by valence band spectroscopy even at room temperature. Nonetheless, (13)C(18)O(2) acts as an incorporation source of (18)O into the Fe-doped SrTiO(3) single crystals. The diffusion coefficient exhibits a peculiar behaviour when Fe concentration increases. No carbon incorporation is observed at all.