RESUMO
The last decade has seen great in electrochromic (EC) technology for smart windows and displays. In this study, WTiOx films formed from TiO2 and WO3 were deposited onto ITO glass with a sheet resistance of 10 Omega cm and on silicon substrates, by pulsed magnetron sputtering using a W and Ti alloy target. The films were deposited at plasma powers 100, 200, 300, 400 and 500 W using a gaseous Ar (150 sccm)/O2 (50 sccm) mixture; the working pressure was fixed at 5E-2 torr. The film thickness increased with the plasma power. However, increasing the plasma power yielded a more crystalline structure with poorer electrochromic properties. The influence of Ti doping and plasma power on the structural, optical and electrochromic properties of the WTiOx thin films was studied. WTiOx films grown at various plasma powers of under 400 W were amorphous. Deposition of films at 400 W yielded the optimal electrochromic properties, with high optical modulation, high coloration efficiency and the lowest color memory effect at wavelengths 400, 550 and 800 nm. An XPS study indicated that Ti can stabilize the valence state of W6+. The improvements caused by the doping with Ti were tested: an optical density (OD) of close to 0.85 and a maximum delta T (%) at 400 nm of 25.8%, at 550 nm of 52.5% and at 800 nm (in the near-IR region) of 62.4%.
RESUMO
In this study, TiWVOx/TiO² thin-films were fabricated using a bipolar pulsed magnetron sputtering technique and were characterized. The results obtained using the X-ray diffraction analysis confirmed the anatase phase structure with a highly oriented TiO² (101) plane. The surface images obtained through scanning electron microscopy revealed the uniform distribution of pebble-like or cell-like clusters with no noticeable crack formation. In this study, an increasing WV alloy pulse power was positively associated with increasing proportions of WOx and VOx in the films. The TiO² with WV alloy sputtered at a power of 50 W was found to be more hydrophilic than TiO² with WV alloy sputtered at 200 W, thereby exhibiting enhanced photocatalytic activity.
RESUMO
Direct methanol fuel cells (DMFC) have been widely studied owing to their simple cell configuration, high volume energy density, short start-up time, high operational reliability and other favorable characteristics. However, major limitations include high production cost, poisoning of the catalyst and methanol crossover. This study adopts a simple technique for preparing Pt-Ru/C multilayer catalysts, including magnetron sputtering (MS) and metal-plasma ion implantation (MPII). The Pt catalysts were sputtered onto the gas diffusion layer (GDL), followed by the implantation of Ru catalysts using MPII (at an accelerating voltage of 20 kV and an implantation dose of 1 x 10(16) ions/cm2). Pt-Ru is repeatedly processed to prepare Pt-Ru/C multilayer catalysts. The catalyst film structure and microstructure were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM), respectively. The cell performance was tested using a potential stat/galvano-stat. The results reveal that the membrane electrode assembly (MEA) of four multilayer structures enhances the cell performance of DMFC. The measured power density is 2.2 mW/cm2 at a methanol concentration of 2 M, with an OCV of 0.493 V.
RESUMO
Titanium nitride coatings are deposited using a hybrid system of cathodic arc evaporation and metal plasma ion implantation. The implant sources selected are Ti and C. Subsequent ion bombardment along with the conventional cathodic arc evaporation are applied to the deposition of TiN film. Implantation causes the increase of nucleation site density, favoring the formation of denser films. The increased density of nucleation sites due to high-energy ion impingement and the surface modification contribute to the fine microstructure of the TiN films. The critical loads evaluated from scratch tests are 60 N, 70 N and 78 N for unimplant-TiN, C+/TiN and Ti2+/TiN, respectively. It demonstrates the advantage of implant pre-treatment on adhesion strength. Pre-implantation of high dose Ti2+ and C+ (about 2 x 10(17) ions/cm2) also results in an improvement of the mechanical properties. Pin-on-disk wear analyses demonstrate a prolonged wear life of TiN coatings by Preimplantation of Ti2+ and C+ ions. The TiN surface modification by pre-implant ions (Ti2+ or C+) is investigated through the microstructure, adhesion strength and wears resistance.