In this work, WO3 thin films were prepared in two steps: First, tungsten (W) films with thickness of 100-300 nm were deposited by DC magnetron sputtering with oblique angle deposition (OAD) technique at 0 and 85. Second, sputtered W films were annealed under air atmosphere at a temperature of 500℃ and different oxidation times for 1-3 h. The structure of WO3 thin films were examined by X-ray diffraction and field emission scanning electron microscope. In addition, the optical and electrochromic properties of the WO3 thin films were measured by a spectrophotometer before and after testing in potassium hydroxide electrolytes. The results showed that the OAD technique can enhance porosity and exert high oxidation in W films. The increase in film thickness and oxidation time indicated that the crystallinity of WO3 films increased. The condition of WO3 films for OAD at 85, thickness of 300 nm, and oxidation time of 1 h showed the best electrochromic property with the highest optical modulation and current density.
In this paper, we aimed to find the sputtering power most suitable for fabricating anodized TiO2 nanotubes (TNTs) with high dimensions (diameter and length). TNTs were synthesized via anodization of Ti films deposited on a glass substrate at varying sputtering power from 50 W to 200 W. The properties of Ti films such as crystallinity, residual stress, and roughness were investigated, which affected the morphology of TNTs. Sputtering power levels of 150 W and 200 W were suitable for TNTs formation via the anodization process in NH4F concentrations from 1.0 wt% to 2.5 wt% due to the increased density and crystallinity of Ti films. Boosting the sputtering power to 200 W increases the roughness of the surface, resulting in a decrease in tube diameter and length. Increasing the sputtering power to 200 W also causes the residual stress of the film to be converted from compression to tensile stress, which allows for more TNTs structures to be formed on the film. Nanotubes fabricated on 150 W sputtered films have been proven to be superior to those fabricated at 200 W in every NH4F concentration in terms of length and diameter. Thus, they are more suitable for applications.
In this study, nickel oxide (NiO) films were prepared on indium tin oxide (ITO) glass by a chemical bath deposition (CBD) at different nickel sulfate (NiSO4) concentrations. The NiO films were verified for their structural properties with field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) while the optical properties were investigated using a spectrophotometer. Moreover, the NiO films were studied to assess their electrochemical properties by cyclic voltammetry in potassium hydroxide (KOH) electrolyte. The results showed that annealed NiO films exhibited the dominant crystal structure of the (111) plane. Meanwhile, the NiSO4 concentration controlled morphological structure between dense and porous structures. The porous structure of NiO film was produced with the NiSO4 concentration in the range of 0.2 M to 1.0 M and the most porous structure was NiSO4 concentration at 0.8 M with a porosity of 64.56%. The optical contrast was calculated between bleached and colored states which were obtained at a maximum of 51.39% for NiO films at 0.8 NiSO4 concentration. Morphological effects and electrochromic properties were highly consistent. Analysis of the cyclic voltammetry (CV) results revealed that the cyclic stability for the highly porous structure of NiO films was more deteriorating than the less porous films.
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