Facile fabrication of Fe-TiO2 thin film and its photocatalytic activity

Fe3+-TiO2 (Fe-TiO2) thin films were successfully prepared using a "sandwich" approach. TiO2 NPs were doped with different Fe3+ content (0.05%, 0.1%, 0.2% molar ratio), and the modified TiO2 NPs were deposited on glass flat support by dip coating. Structural, morphological, optical, and photocatalytic properties of Fe-TiO2 thin films were studied. XPS spectra confirm the presence of Ti, Fe, O, and defective -OH groups at the material surface. The Fe 2p spectrum demonstrates the existence of Fe3+. SEM images indicate that the incorporation of Fe3+ deforms in some degree the homogeneity of the TiO2 system. Additionally, incorporation of Fe3+ ions to the network creates an impurity band near the VB due to the oxygen vacancies, resulting in the reduction of the effective optical band gap. Photocatalytic activity of fabricated thin films in the elimination of sulfamethoxazole (SMT) follows pseudo first-order kinetics. The highest SMT removal yields were achieved using the sample with 0.05%Fe. Additionally, the use of greater thicknesses improves the removal performance. However, material detachment limits the maximum usable value around 6 mu m. Finally, stability and reusability of catalysts were confirmed studying the photocatalytic activity over three cycles and evaluating that no Fe3+ leaching occurred.This research was supported by Ministerio de Economia y Competitividad (Project AGL2016-80507-R) and University of Cadiz (Project PR2018-048)

Analysis of the Visual Appearance of AISI 430 Ferritic Stainless Steel Flat Sheets Manufactured by Cool Rolling and Bright Annealing

This article reports on the relation between the surface topography and the optical reflectance, both total and diffuse, of different samples of AISI 430 ferritic stainless steel. Gaussian filters with different cutoff wavelengths were applied to the height maps of the surface topography of the samples, to separate the different scales of surface roughness involved in optical scattering in the visible range of the spectrum. Significant anisotropy, related to the rolling process, was found in the topography. An effective roughness slope parameter was defined from the dependence of the ratio between the root mean square height and the autocorrelation length on the cutoff wavelength. This roughness slope demonstrated an exceptionally good linear relationship with CIE 1931 luminance, which was calculated from the diffuse reflection spectra. The color uniformity of the samples was analyzed based on their CIE L*a*b* coordinates under daylight and LED illumination. The results confirmed the strong influence of manufacturing process on the surface characteristics of AISI 430 ferritic stainless steel sheet products with a bright finish.This work was co-financed by the 2014-2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia. Project reference: FEDER-UCA18-106321

Tracking the optical constants of porous vanadium dioxide thin films during metal-insulator transition: Influence of processing conditions on their application in smart glasses

Vanadium dioxide (VO2) is widely recognized as a thermochromic material with great potential for application in smart glazing for energy-efficient buildings. The monoclinic (M1) VO2 phase undergoes a first-order reversible phase transition from the semiconductor to the rutile metallic state. In this study, an M1 VO2 porous film was synthesized via a polymer-assisted sol-gel route. Processing parameters, such as drying and reduction temperatures, were varied to evaluate their influence on the thermochromic behavior of VO2 and to determine the necessary trade-off between a significant thermochromic effect and high luminous transmittance. Film-silica glass-film systems with luminous transmittance close to 80% and IR solar modulation ability as large as 20% were prepared. By tracking the optical constants of the films during the thermochromic process, the changes produced at the microscopic level in the material could be correlated with its macroscopic behavior when used as an energy-saving material.Y J. Outon acknowledges the support by the Spanish Ministerio de Educacion y Cultura through grant FPU19-02638. M. Dominguez ac-knowledges the support by the Spanish Ministerio de Ciencia, Innovacion y Universidades under project EQC2018-004704-P. The authors thank the University of Cadiz and IMEYMAT for financing the mutual facilities available at the UCA R&D Central Services (SC-ICYT) and the IMEYMAT Institute project reference PLP2020335-1 respec-tively. The authors also acknowledge J. Gonzalez and F. Delgado for their assistance in the preparation of the STEM specimens

Synthesis and applications of TEOS/PDMS hybrid material by the sol–gel process

An organically modified silicate, ormosil, was synthesized with an inorganic precursor, (tetraethoxysilane, TEOS) and an organic precursor [poly(dimethylsiloane), PDMS] through sol–gel chemistry. The bonding characteristics of the composite were investigated via glass transition temperatures ( T g ) and a hybridization model of TEOS and PDMS was illustrated schematically. The variation of T g with the ratios of HCl/TEOS and TEOS/PDMS was observed. Ormosil sols for coating were obtained with TEOS/PDMS ratios from 60:40 to 90:10 and the best ormosil sol as the host of a dye laser was obtained from a ratio of 90:10. As the HCl/TEOS ratio was increased, higher T g values were obtained but holes formed in the coated surface and laser output diminished. Dimerization of organic molecules was detected in the enlarged pore size of the host due to an increase in the ratio. The effects of HCl and PDMS on bonding characteristics were measured by dynamic mechanical thermal analyser (DMTA). UV/VIS spectrophotometry, spectrofluorimetry and scanning electron micrography (SEM) were used to obtain the properties relating to this study of inorganic–organic composites. Copyright © 1999 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34749/1/829_ftp.pd

Fe3O4-TiO2 Thin Films in Solar Photocatalytic Processes

The optical properties of 5wt% Fe3O4-TiO2 thin films were evaluated in detail with the aim of proposing a mechanism for solar photocatalytic processes and highlighting the advantages over the use of bare TiO2. The results showed that the incorporation of 5wt% Fe3O4 enhanced the optical properties by a redshift to a wavelength in the visible range, reducing the anatase/rutile band gap energy from 3.2 eV to 2.8 eV. Photoluminescence studies reveal a superior separation efficiency of photoexcited electron-hole pairs when Fe3O4 nanoparticles (NPs) are present in the photocatalyst. X-ray photoelectron spectroscopy spectra confirm the presence of Fe3O4 and existence of a chemical bonding between TiO2 and Fe3O4 NPs. Moreover, in this study, a mechanism of solar photocatalytic processes involving Fe3O4-TiO2 thin films is proposed and it is supported by experimental results. Finally, solar photocatalytic experiments were carried out, indicating that the effectiveness for the removal of the selected pharmaceutical is considerably improved when the composite material is used as catalyst. Furthermore, it was demonstrated that the photocatalytic activity of the prepared Fe3O4-TiO2 thin films depends on their thickness, achieving the highest pharmaceutical removal yields using the 2 mu m thick sample. The stability and reusability of the catalyst was confirmed studying the photocatalytic activity over three cycles

Preparación y caracterización de láminas delgadas de óxido de vanadio obtenidas por vía sol-gel y recubrimiento por inmersión

Resumen del proyecto de líneas prioritarias titulado "Preparación y caracterización de láminas delgadas de óxido de vanadio obtenidas por vía sol-gel y recubrimiento por inmersión" del IMEYMAT

Engineering of III-Nitride Semiconductors on Low Temperature Co-fired Ceramics

This work presents results in the feld of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fred Ceramics has been used, as a noncrystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these felds of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using diferent bufer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes