Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Lithiation of Metal-Oxide Thin Film Layers on Zto/Ag Electrodes by Magnetron Sputtering for Electrochromic Devices(Izmir Institute of Technology, 2023) Deveci̇, Enver; Özyüzer, Lütfi̇; Ünal, Uğur; 01. Izmir Institute of TechnologyElectrochromism is a property of materials that undergoes a reversible transition from a colorless or transparent state to a colored state under the action of electric voltage or current. What makes electrochromic materials special is by controlling the voltage applied to the material. Among these electrochromic materials, metal oxides such as WO3 and NiOx are metal oxides that are frequently used. Electrochromic devices are devices that do not consume much energy and can save a lot of energy. A typical electrochromic device consists of five different thin film layers: an ionic conductive layer (electrolyte) and transparent conductive oxides (ZTO, ITO, etc.) are located between the main electrochromic layer and the secondary electrochromic layer.In this study, instead of the traditionally used transparent conductive electrode ITO, ZTO/Ag/ZTO (Z=Zn2SnO4) electrode with high optical transmittance and electrical conductivity was used, thus cost-effective and more efficient electrochromic devices were produced. Here, 3 layers of thin film (WO3,Ta2O5, NiOx) coating on Glass/ZAZ samples was grown by magnetic sputtering method at room temperature and the production parameters were optimized. Here, WO3 and NiOx are used as thin film electrochromic layer, while Ta2O5 is used as solid-state electrolyte. The electrochemical properties of the metal oxide WO3 and NiOx coatings used here were measured in 1 M LiClO4-PC electrolyte using a conventional three-electrode configuration. In the next step, to test the performance of WO3 and NiOx electrochromic films, Li-based liquid electrolyte was mounted on our electrochromic device (ZAZ/NiOx/Ta2O5/WO3/ZAZ), which has a five-layer battery-like structure and tested.Master Thesis Preparation and Determination of Rheological Behavioour of Fine Strontium Titanate Powder Suspensions(Izmir Institute of Technology, 1999) Ünal, Uğur; Çiftçioğlu, Muhsin; Çiftçioğlu, Muhsin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this project, strontium titanate powders were prepared by using solgel and Pechini methods. In sol-gel method, the powders were prepared by mixing the Ti02 sol and Sr(N03h solution. Precipitation was observed after the addition of Sr(N03)2 solution. Two powders were prepared by each method. In sol-gel method, acid:alcohol ratio was changed. In Pechini method, 50% of citric acid was substituted with polyacrylic acid. The characterization of the powders were performed by Fourier Transform Infrared Spectrophotometer (FTIR), Thermogravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), X-Ray Diffraction and Optical Microscope. The calcination temperature of 650°C was chosen for sol-gel powder according to TGA data. XRD pattern showed that this temperature was not high enough to form complete SrTi03 phase, but no peaks related to nitrates or organic groups was observed in FTIR spectra. Sintering studies indicated that the agglomeration of sol-gel powder was very strong because the relative densities were very small. Pechini powders had weaker agglomerates and sintered to higher densities. The diameters of the Pechini powders were found as in the range of 0.2-0.5 um. The powders were dispersed in white oil and the rheological behaviour of these dispersions was studied by a rheometer. Several runs at different shear rates, and volume fractions were done. The suspensions without surfactant showed shear-thinning behavior, which indicates that the suspensions were flocculated. The addition of surfactant in certain amount produced stabilized suspenSIOns. The stabilized suspenSIOns showed Newtonian or Dilatant behaviour. The increase in the solids loading did not show significant change in the viscosity of stabilized suspension.