Mühendislik ve Doğa Bilimleri Fakültesi

Permanent URI for this communityhttps://gcris.khas.edu.tr/handle/20.500.12469/36

Browse

Now showing 1 - 5 of 5

Citation Count: 2
Characterization of MWCNT-TiO2 Qps and TiO2 QDs in self-assembled films
(Elsevier, 2017) Akkaya Arier, Ümit Özlem; Uysal, Bengü Özuğur
In this study the solution which includes TiO2 quantum dots (QDs) was mixed with the multi-wall carbon nanotubes (MWCNTs) to prepare MWCNT-TiO2 QDs composite films. The effect of microstructures on the structural and optical properties of MWCNT-TiO2 QDs composite films was evaluated. The activation energy for crystallite growth of TiO2 QDs which are produced in brookite phases was calculated as 20.3 kJ/mol. The properties of MWCNT-TiO2 QDs composite films were characterized by X-ray diffraction (XRD) scanning electron microscopy (SEM) atomic force microscopy (AFM) and ultraviolet-visible absorption spectroscopy (UV-vis). (C) 2017 Elsevier GmbH. All rights reserved.
Citation Count: 3
The effects of Dea:water ratio on the properties of ZnO nanofilms obtained by spin coating method
(Elsevier Science, 2014) Akkaya Arier, Ümit Özlem; Uysal, Bengü Özuğur
In this work the ZnO were fabricated with the sol-gel spin coating method and the effects of the Dea:water ratios on the properties of the as-prepared ZnO thin films were determined by using a X-ray diffractometer transmission electron microscope scanning electron microscope atomic force microscope ultraviolet-visible spectrophotometer and spectrophotometer. Experimental results indicated that the Dea:water ratio affected the structural and optical properties of the ZnO films considerably. The activation energy for the particle growth of ZnO nanofilms and the effects of the Dea:water ratios on the band gap values of the ZnO films were investigated. The film has an activation energy of 26.3 kJ/mol and optical band gap of 3.27-3.31 eV is proportional to the Dea:water ratio. (c) 2014 Elsevier Ltd. All rights reserved.
Citation Count: 4
Effects of Precursor Parameters on the Optical and Electrical Properties of AZO Nano-Composite Films
(Elsevier GMBH Urban & Fischer Verlag, 2016) Akkaya Arier, Ümit Özlem; Uysal, Bengü Özuğur
Al doped ZnO (AZO) nano-composite films were synthesized on glass substrates with the sol gel spin coating method at the room temperature. The activation energy of AZO nano-composite films was calculated to be 49 kj/mol for the particles growth. The electrical structural and optical properties of AZO films were determined by changing ZnO:water and ZnO:Al ratios. ZnO:water and ZnO:Al ratios play an important role in controlling the electrical conductivity of the AZO nano-composite films. The optimum doping ratio of Al was found to be 2% in terms of the lowest resistivity and above 2% Al-doping concentration the surface resistivity of AZO nano-composite films starts to increase. The optical highest transmittance of the films of 86% in visible region and low surface resistivity of 70 Omega/square can be obtained for the optimum doping ratio of Al. (C) 2016 Elsevier GmbH. All rights reserved.
Citation Count: 4
The Electrochromic Performances of Single Phase VO2 Nanoparticled Films
(Elsevier Science SA, 2016) Akkaya Arier, Ümit Özlem; Uysal, Bengü Özuğur
In the present work pure phase vanadium oxide VO2 nanoparticled films were synthesized using acetate based sol-gel precursors. The effect of the water: Vanadyl acetylacetonate ratio on electrochemical and structural properties of nanostructured vanadium oxide films was examined. The X-ray diffraction studies indicated that very strong crystallization of the VO2 monoclinic phase occurred for the as-deposited films at the annealing temperature of 500 degrees C. According to the atomic force microscopy and scanning electron microscopy measurements the size and morphology of the granular structured film depend on the water: Vanadyl acetylacetonate ratio. I-V curve spectra were used to compute several characteristics of the films coated on indium tin oxide substrates such as the optical density color efficiency and diffusion coefficient. Even though water: Vanadyl acetylacetonate ratio of 0.1 is expected to give the highest color efficiency value (33 cm(2)/C) higher diffusion coefficient (3.15 x 10(-12) cm(2)/s) is observed in the ratio of 0.01. As a result the correlation between the ratios and electrochromic properties of the films was established. (C) 2016 Elsevier B.V. All rights reserved.
Citation Count: 2
Tailoring The Electrical and Optical Properties of Carbon Nanotube Reinforced Transparent Tio 2 Composites by Varying Nanotube Concentrations
(World Scientific Publ Co Pte Ltd, 2019) Uysal, Bengü Özuğur; Akkaya Arier, Ümit Özlem; Pekcan, Önder
In the present work multi-walled carbon nanotube (MWCNT)-doped TiO 2 nanocomposite films were synthesized by sol-gel method. The influence of nanotube concentration on the structural electrical and optical properties of the films was investigated. The beneficial effects of the addition of carbon nanotubes into a TiO 2 film and titania-coated MWCNTs have much in common. On the other hand this work contributes to the previous studies in terms of the optical and electrical properties of MWCNT. For this reason MWCNT/rare brookite-phased TiO 2 matrix as simple sol-gel deposited composite films were investigated in our study. The XRD studies showed that the composite film has a brookite crystal structure at the annealing temperature of 450C. According to the surface morphology investigations SEM image of nanocomposite film shows that composite film has a granular and rod-like structure. The absorbance measurements of the films were carried out by the UV-Vis spectrophotometer to investigate transparency and to calculate the bandgap energy of composite films. The surface resistivity of the MWCNT-doped TiO 2 composites decreased from 2.50×1010 to 2.20×109 ohm/sq with increase in MWCNT content. © 2019 World Scientific Publishing Company.

Browse

Browsing Mühendislik ve Doğa Bilimleri Fakültesi by Author "Akkaya Arier, Ümit Özlem"