Yalcin Urfa | Ahmet Altindal

Makale | 2021 | INDIAN ACAD SCIENCES

Poly(3,4-ethylenedioxythio-phene):poly(styrenesulphonate) (PEDOT:PSS) nanofibres were first prepared via electrospinning method. Microstructural arrangement of the nanofibres was investigated by scanning electron microscopy technique. Then, the effect of beta irradiation with different absorbed doses on their impedance spectra were investigated in the frequency range from 5 to 13 x 10(6). It was observed that beta irradiation leads to a considerable decrease in both real and imaginary parts of the complex dielectric function, and alternating current conductivity of the nanofibres. The obtained frequency dependent conductivity data w . . .ere discussed in terms of pair approximation. It was established that, for all beta irradiation doses, the frequency dependence of the conductivity is characterized by the presence of four frequency regions with different slopes. Analysis of the impedance data revealed that chain scission via chain cross-linking and free radical formation are most likely mechanisms for changes in impedance parameters. Two clear semicircles in Nyquist plot have been successfully explained by employing two parallel R-CPE equivalent circuits in series configuration. An overall evaluation of the obtained data indicates that electrospun PEDOT:PSS nanofibres have great potential for the development of highly sensitive impedance-based beta radiation sensor Daha fazlası Daha az

Yalcin Urfa | Vahit Corumlu | Ahmet Altindal

Makale | 2021 | ELSEVIER SCIENCE SA

This study reports the influence of gamma ray irradiation of various doses in the range of 1?150 kGy on methanol sensing performance and adsorption kinetics of ZnO nanoparticles based sensors. ZnO nanoparticles were synthesized via sol-gel method and characterized with X-ray diffraction (XRD), transmission electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques. The results revealed that the methanol sensing performance of ZnO nanoparticles based sensor including sensitivity, response and recovery times improved by the gamma ray irradiation. Additionally, Elovich equation, Ritchie?s equation and pseu . . .do first order model were selected to follow the methanol adsorption process. The preliminary result of the methanol adsorption kinetic studies revealed that the adsorption kinetics strongly depends on the gamma irradiation dose. Among other kinetic models investigated, the pseudo first-order equation was the best to describe the adsorption kinetics of methanol on ZnO nanoparticles up to 50 kG dose of gamma ray, as evidenced by the highest correlation coefficients. On the other hand, for higher doses than of 50 kGy of gamma irradiation, our analysis showed that Elovich equation generates a straight line that best fit to methanol adsorption data on ZnO nanoparticles Daha fazlası Daha az

Erem Ahmetali | Hande Pekbelgin Karaoglu | Yalcin Urfa | Ahmet Altindal | Makbule Burkut Kocak

Makale | 2020 | ELSEVIER SCIENCE SA

In this study, the three novel fluoro substituted asymmetric zinc phthalocyanines substituted with 3-hydroxy-3-methyl-1-butynyl (3), ethynyl (4), and 4-nitrophenylethynyl (5) groups were synthesized and characterized by Fourier-transform infrared spectrophotometer, ultraviolet-visible, proton nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. The thickness dependence of relative humidity sensing performance of these compounds using quartz crystal microbalance transducers in a broad operating range of humidity was investigated. Results from this preliminary analysis indicated . . . that responses and the response and recovery times of the 3-5 compound-based relative humidity sensors strongly depended on the thickness of the sensory layer. Experimental studies indicated that the optimized thickness as 450 nm produces a good sensitivity, and the best response and recovery times. The relative humidity sensing results demonstrated that the quartz crystal microbalance sensor coated with peripherally substituted unsymmetrical zinc(II) phthalocyanines bearing nitrophenyl group was the most useful coating for the relative humidity sensing Daha fazlası Daha az