Scientific Papers in SCI

ZnWO4 based powder photocatalyst have been successfully prepared by calcining a co-precipitated precursor (ZnWO) obtained from aqueous Zn2+ and WO4 2− solutions at pH = 7, without surfactants addition. The as-formed sample was characterized by XRD, N2-absorption, SEM, TEM, DRS and XPS. Both techniques, XRD and XPS results showed that prepared sample corresponds to a crystalline, Zn-enriched composition, ZnWO4 indicating the formation of a ZnWO4-(ZnO) composite, whit ca. 10 wt.-% of ZnO confirmed by XRF analysis. Photocatalytic activities towards degradation of Rhodamine B (RhB), Methyl Orange (MO) and Phenol, under UV-illumination, was investigated not only by monitoring the percentages of conversion of substrates, but also by estimating the corresponding percentages of mineralization that accompany the photocatalytic process. Comparative substrateconversion rates estimated per surface area unit of catalyst, showed that the activity for ZnWO4-(ZnO) composite is similar to that for TiO2(P25), at least for MO and RhB, and even higher that for TiO2(P25) in respect to phenol conversion. By adding TEA to the synthesis procedure, a composite named as ZnWO4-ZnO-(pH = 10)-600 is generated, which has a higher proportion of ZnO (ca. 39 %) and superior specific surface area than the so-called ZnWO4-(ZnO) sample. Furthermore, the photocatalytic degradation of MO using the former material indicates that it is superior to ZnWO4-(ZnO) and even that TiO2(P25) itself under the same operational conditions. 

Highly anisotropic resistivity surfaces are produced in indium tin oxide (ITO) films by nanoscale self-organization upon irradiation with a fs-laser beam operating at 1030 nm. Anisotropy is caused by the formation of laser-induced periodic surface structures (LIPSS) extended over cm-sized regions. Two types of optimized structures are observed. At high fluence, nearly complete ablation at the valleys of the LIPSS and strong ablation at their ridges lead to an insulating structure in the direction transverse to the LIPSS and conductive in the longitudinal one. A strong diminution of In content in the remaining material is then observed, leading to a longitudinal resistivity rho(L) approximate to 1.0 omega center dot cm. At a lower fluence, the material at the LIPSS ridges remains essentially unmodified while partial ablation is observed at the valleys. The structures show a longitudinal conductivity two times higher than the transverse one, and a resistivity similar to that of the pristine ITO film (rho approximate to 5 x 10(-4) omega center dot cm). A thorough characterization of these transparent structures is presented and discussed. The compositional changes induced as laser pulses accumulate, condition the LIPSS evolution and thus the result of the structuring process. Strategies to further improve the achieved anisotropic resistivity results are also provided.