Browsing by KHAS Author "Tepehan, Galip Gültekin"
Now showing items 1-11 of 11
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Atomic force microscopy and spectroscopy studies of annealed Ce/Ti/Zr mixed oxide thin films prepared by sol-gel process
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Publisher and Date:(Elsevier Science Bv, 2006)Mixed Ce/Ti/Zr oxide thin films with a molar ratio of 0.5:0.25:0.25 were prepared using the sol-gel process and deposited on glass substrates by the dip coating technique. The effect of heat treatment temperature on surface morphology of the films was examined by atomic force microscopy AFM. The optical transmittance and reflectance of the films were measured over the spectral range from 350 to 1000 nm. The refractive index and extinction coefficient and thickness of the films were determined as ...
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Characterization Of Mps Capped Cds Quantum Dots And Formation Self-Assembled Quantum Dots Thin Films On A Glass Substrate
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Publisher and Date:(Natl Inst R&D Materials Physics, 2011)Colloidal powdered and thin film forms of MPS capped CdS quantum dots have been produced by combination of colloidal chemistry and sol-gel method. Nanoparticles were self-assembled directly on a glass substrate using spin coating method without introducing any matrix. Colloidal powdered and thin film forms were characterised by absorbance photolimunescence XRD FT-IR HRTEM and AFM measurements. The HRTEM images give a grain size of 2.5-3.0 nm and this is in agreement with the values found in the ...
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Derivation of the optical constants of spin coated CeO2-TiO2-ZrO2 thin films prepared by sol-gel route
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Publisher and Date:(Pergamon-Elsevier Science Ltd, 2011)Ternary thin films of cerium titanium zirconium mixed oxide were prepared by the sol-gel process and deposited by a spin coating technique at different spin speeds (1000-4000 rpm). Ceric ammonium nitrate ce(NO3)(6)(NH4)(2) titanium butoxide Ti[O(CH2)(3)CH3](4) and zirconium propoxide Zr(OCH2CH2CH3)(4) were used as starting materials. Differential calorimetric analysis (DSC) and thermogravimetric analysis (TGA) were carried out on the CeO2-TiO2-ZrO2 gel to study the decomposition and phase transition ...
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Electrochromic properties of heat-treated thin films of CeO2-TiO2-ZrO2 prepared by sol-gel route
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Publisher and Date:(Elsevier Science Bv, 2008)CeO2-TiO2-ZrO2 thin films were prepared using the sol-gel process and deposited on glass and ITO-coated glass substrates via dipcoating technique. The samples were heat treated between 100 and 500 degrees C. The heat treatment effects on the electrochromic performances of the films were determined by means of cyclic voltammetry measurements. The structural behavior of the film was characterized by atomic force microscopy and X-ray diffraction. Refractive index extinction coefficient and thickness ...
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Growth kinetics of MPS-capped CdS quantum dots in self-assembled thin films
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Publisher and Date:(Springer, 2012)For this study we prepared colloidal CdS quantum dots using 3-mercaptopropyltrimethoxysilane as capping agent. Colloidal CdS quantum dots were directly deposited on glass substrates by a spin-coating process. Coated substrates were heat-treated between 225A degrees C and 325A degrees C for various heat treatment time intervals to investigate the growth kinetics of the quantum dots. Results showed that sizes of the CdS quantum dots grew approximately from 2.9 to 4.6 nm and the E (1s1s) energy values ...
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Influence of pH on the optical and structural properties of spin coated CeO2-TiO2 thin films prepared by sol-gel process
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Publisher and Date:(Elsevier Science Bv, 2007)Optical and structural properties of mixed CeO2-TiO2 thin films have been investigated by varying the pH of the coating sol. The films were prepared by sol-gel process using spin-coating technique with a spin speed of 2500 rpm. The optical and structural properties of films were examined by a spectrophotometer AFM and XRD. Optical constants and thickness of the CeO2-TiO2 thin films have been determined with respect to the pH of the coating bath before deposition. The refractive index at 550 nm ...
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Modeling the optical properties of WO(3) and WO(3)-SiO(2) thin films
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Publisher and Date:(Elsevier Science Bv, 2008)The optical properties and surface morphology of sol-gel spin coated WO(3) and WO(3)-SiO(2) composite films annealed at 250 and 400 degrees C are investigated. For the purpose of extracting the optical parameters of the films a novel form for the dielectric function is introduced consisting of two Tauc-Lorentz oscillators and an Urbach tail component which is suited for amorphous multi-transition materials with substantial subgap absorption. The evolution of the refractive indices transmittances ...
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Optical and structural properties of sol-gel made Ce/Ti/Zr mixed oxide thin films as transparent counter electrode for electrochromic devices
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Publisher and Date:(Elsevier Science Bv, 2008)Ce/Ti/Zr mixed oxide thin films were prepared using sol-gel process with mole ratios from 45/5 to 5/45 of Ti/Zr and 50 of Cc and deposited by dip coating technique. Optical electrochromic and structural properties of such films were investigated. The thickness refractive index and extinction coefficient of the films were calculated through transmission and reflection measurement by an nkd spectrophotometer. The surface morphology and structural behaviors of the films were characterized by atomic ...
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Optical and structural properties of Ta2O5-CeO2 thin films
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Publisher and Date:(Elsevier Science Bv, 2007)In this study the sol-gel spin-coating method has been used to make Ta2O5-CeO2 thin films. These films have been prepared in various composition ratios to observe changes in their optical and structural properties. Reflectance and transmittance spectra were collected in the spectral range of 300-1000 nm and were accurately fit using the Tauc-Lorentz model. Film thicknesses refractive indices absorption coefficients and optical band gaps were extracted from the theoretical fit. The highest refractive ...
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Preparation and characterization of self-assembled thin film of MPS-capped ZnS quantum dots for optical applications
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Publisher and Date:(Hindawi Publishing Corporation, 2012)For this study we prepared colloidal ZnS quantum dots using 3-mercaptopropyltrimethoxysilane (MPS) as the capping agent. Colloidal ZnS quantum dots were directly deposited on glass substrates by a spin coating process. Therefore self-assembled films made of ZnS quantum dots in a SiO2 network were obtained using only one production step. The films were heat-treated at 100 degrees 125 degrees 150 degrees 175 degrees and 200 degrees C in an N-2 atmosphere. The results showed that the dimension of ...
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Seventh International Meeting on Electrochromism (IME-7) Istanbul Turkey 3-7 September 2006
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Publisher and Date:(Elsevier Science Bv, 2008)
