Photodegradation of Pollutants in Air: Enhanced Properties of Nano-TiO2Prepared by Ultrasound

Nanocrystalline TiO2samples were prepared by promoting the growth of a sol–gel precursor, in the presence of water, under continuous (CW), or pulsed (PW) ultrasound. All the samples turned out to be made of both anatase and brookite polymorphs. Pulsed US treatments determine an increase in the sample surface area and a decrease of the crystallite size, that is also accompanied by a more ordered crystalline structure and the samples appear to be more regular and can be considered to contain a relatively low concentration of lattice defects. These features result in a lower recombination rate between electrons and holes and, therefore, in a good photocatalytic performance toward the degradation of NOxin air. The continuous mode induces, instead, the formation of surface defects (two components are present in XPS Ti 2p3/2region) and consequently yields the best photocatalyst. The analysis of all the characterization data seems to suggest that the relevant parameter imposing the final features of the oxides is the ultrasound total energypervolume (Etot/V) and not the acoustic intensity or the pulsed/continuous mode

Magnetic and Electric Transport Properties of Fe-Hf-o Films Prepared by Supersonic Plasma Jet Method

The influence of deposition conditions on the structure, magnetic properties, and electrical resistivity of Fe-Hf-O films, prepared by the supersonic plasma jet deposition technique, was investigated. Composition of the films was controlled by the nozzle composition and the working gas. It varied in the limits: 15-68 at.% of Fe, 0.5-8 at.% of Hf and 29-80 at.% of O. The films were mainly X-ray amorphous. Some of them showed a weak and broad peak near the [110] reflection of α-Fe indicating the presence of Fe-rich clusters in an amorphous matrix. Depending on the deposition parameters the magnetic properties vary from paramagnetic to ferromagnetic ones. The electrical resistivity changes from the metallic to the hopping type. In some samples a large negative magnetoresistance is observed