Yazar "Er, Irmak Karaduman" seçeneğine göre listele

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    Enhancing the Co gas sensing properties of ZnO thin films with the decoration of MWCNTs
    (Springer, 2019) Ozutok, F.; Er, Irmak Karaduman; Acar, S.; Demiri, S.
    Multi-walled carbon nanotubes (MWCNTs) onto flower-like patterned ZnO seed layers were prepared by spin coating method. The etching of the MWCNTs was examined by HCl acid treatment. The effect of structural, morphological and elemental properties of the ZnO/MWCNTs were determined by XRD, SEM, and EDX, respectively. The gas sensing properties of ZnO seed layer and MWCNT/ZnO nanocomposites were studied as a function of operating temperature and gas concentration. The incorporation of MWCNT were given results such as reducing the operating temperature to 70 degrees C and enhancement in sensor response for 25ppm CO gas. It was obtained that the highest sensing response of 62% at 70 degrees C for raw-MWCNTs/ZnO sensor as compared to etched-MWCNT/ZnO and ZnO sensor which gave a sensing response of 19% and 21% at operating temperature of 70 degrees C and 150 degrees C, respectively. Results showed that the deposition of metal oxide sensors with MWCNT is a promising strategy for improvement of CO gas sensing properties.
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    Investigation of H2S gas sensing performance of Ni:WO3 films at room temperature: nickel precursor effect
    (Springer, 2022) Er, Irmak Karaduman; Sarf, Fatma; Yakar, Emin
    In this work, pure and nickel-doped WO3 films were produced by chemical bath deposition on In-doped SnO2 (ITO) substrates without annealing process. To synthesize the Ni:WO3 films, two different types of nickel precursors were used as NiSO4 and NiCl2. The influence of Ni doping using different Ni precursors on the structural, morphological, optical, and gas sensing properties of WO3 films toward H2S gas was investigated in detail. All samples have monoclinic WO3 polycrystallization where a substitution of Ni2+ ions with W6+ mi olmali ions is detected from the slight shift in x-ray diffraction patterns with the Ni doping process. With nickel chloride source, the synthesized Ni:WO3 samples exhibit nano-ball shapes with different dimensions on the film surfaces. Optical band gap energy severely decreases with nickel doping due to increasing oxygen vacancies, especially when nickel chloride is used as a precursor source in Ni:WO3 samples. Ni2+ ions introduction in WO3 host lattice has improved H2S gas detection capability; however, the biggest positive effect came from the NiSO4 precursor with increasing solubility and improved growth process. The response to 50 ppb H2S gas at room temperature was calculated as 7%, 11%, and 23% for pure WO3, NiCl2-based Ni:WO3, and NiSO4-based Ni:WO3 sensors, respectively. When the gas selectivity property was studied for NiSO4-based Ni:WO3 sensors, they showed more selectivity against H2S gas compared to H-2, benzene, methanol, etc. It is found that precursor type has an incredible impact on the H2S, reducing gas sensing properties in doped metal oxide gas sensor applications.
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    Optical and Electrical Characterization of Crystallized M:$WO_3$ (Cu, Fe, Ni) Films in Acidic Medium
    (2024) Yakar, Emin; Er, Irmak Karaduman; Sarf, Fatma
    Pure and metal (M) doped [copper (Cu), nickel (Ni) and iron (Fe)] $WO_3$ films have been produced on In:$SnO_2$ (ITO) slides by using facile chemical bath deposition and then annealed at 500 oC for 2 h. Structural, morphological, electrical and optical properties of the produced $WO_3$-based films were examined. Monoclinic $WO_3$ phase were observed in all the samples, and the peak intensities were decreased by metal inclusion with heterogeneous film growth on ITO substrate. Slight shifts from defect related emission peaks (blue and green) were observed in metal-substituted $WO_3$ samples from PL study. An optical band gap was observed to decrease in M:$WO_3$ samples. The surface resistance values were significantly reduced by metal additives compared to its pure counterpart, especially by the inclusion of nickel ions in $WO_3$. The results indicated that nucleus growth and thereby impurity/defect-related surfaces had a serious effect on the optical and electrical properties of M:$WO_3$ films.
  • Küçük Resim
    Öğe
    Substrate critical effect on the structural and H-2 Gas sensing characteristics of solution-processed Zn0.075Cu0.025O films
    (IOP Publishing, 2021) Sarf, Fatma; Er, Irmak Karaduman; Yakar, Emin; Acar, Selim; Yakar, Emin
    In this study, we report the synthesis of Zn0.075Cu0.025O films by chemical bath deposition to determine the effect of substrate (glass slide or ZnO seed layer) on the structural and H2 gas sensing properties of the produced films. The crystal phase, structural topography, surface morphology, and functional groups of the as-synthesized films as well as H2 gas sensing properties were investigated. Although both films have a hexagonal wurtzite structure, ZnO seed layer-based Zn0.075Cu0.025O film is more crystalline than glass slide-based Zn0.075Cu0.025O films. ZnO seed layer-based Zn0.075Cu0.025O films exhibited much more nanorod and fewer nanosphere forms compared to glass slide-based Zn0.075Cu0.025O films. EDX analysis and Raman spectra of both samples confirmed the presence of defects in Cu: ZnO samples. ZnO seed layer-based sensors showed higher response (140%) and lower operating temperature (80 °C) compared to glass slide-based sensors(87% response and 140 °C operating temperature). The most important thing to note here is that the fabricated sensors exhibited a high response at room temperature. The responses at room temperature were found as 46% and 23% for the ZnO seed layer-based and glass slide-based sensors, respectively. Sensors operating at room temperature are especially important for commercial applications.
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    The role of rare-earth metal (Y, Ru and Cs)-doped ZnO thin films in NH3 gas sensing performances at room temperature
    (Springer, 2020) Sarf, Fatma; Er, Irmak Karaduman; Yakar, Emin; Acar, Selim
    Pure and rare-earth metal [Yttrium (Y), Ruthenium (Ru) and Caesium (Cs)]-doped ZnO thin films were deposited onto In-doped SnO2 substrates by chemical bath deposition. The present study detailed investigated the effect of rare-earth metal-doped ZnO on NH3 gas sensing. X-ray diffraction analysis indicated that the incorporated rare-earth metal ions substitute Zn sites in the ZnO lattice. Dimension of ZnO films decreased with rare-earth metal doping which detected from surface morphology images. The response of 100 ppb NH3 gas was calculated to be 0.80 (200 degrees C), 14.00 (90 degrees C), 17.00 (50 degrees C), and 10.00 (120 degrees C) for the pure, Y-, Ru-, and Cs-doped ZnO films, respectively. In addition, the response of 15 ppm NH3 gas at room temperature was calculated to be 0.20, 27.00, 57.00, and 18.00 for undoped Y-, Ru-, and Cs-doped ZnO films, respectively.
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    Varying electrical and dielectric properties of Ni:SnO2 films by MWCNTs and GNPs coating
    (Iop Publishing Ltd, 2022) Sarf, Fatma; Er, Irmak Karaduman; Ajjaq, Ahmad; Cagirtekin, Ali Orkun; Yakar, Emin; Acar, Selim
    In this research, pure SnO2 and Ni-doped SnO2 (Ni:SnO2) nanocomposite films were produced by chemical bath deposition method and the latter were coated with multi-walled carbon nanotubes (Ni:SnO2/MWCNTs) or graphene nanoplatelets (Ni:SnO2/GNPs) by spin coating. All samples have tetragonal rutile SnO2 structure with the presence of carbon (002) peak in MWCNTs- or GNPs-coated films. Crystallite size of SnO2 films decreased remarkably with Ni doping followed by a slight decrease with MWCNTs coating and slight increase with GNPs coating. Scanning electron microscope images manifested a dispersed agglomerative nature of SnO2 nanoparticles which reduced especially with MWCNTs coating due to the porous surface provided by carbon nanotubes. From the photoluminescence measurements, oxygen defects-related peaks were spotted in the SnO2-based structures with different luminescence intensities. The most significant decrease in resistance was observed with the addition of GNPs into Ni-doped SnO2 nanocomposites compared to the other produced films mainly due to the synergetic effect that promotes excellent charge transfer between surfaces of Ni:SnO2 and graphene nanosheet. The huge increase in conductivity of GNPs-coated films led to a huge increase in dielectric losses and this followed by a drop down of dielectric constant of the GNPs-coated films.