Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

Browse

Filters

2020 - 20224

Settings

Start date: 2020Scopus Q: search.filters.scopusQuartile.Q4

Search Results

Now showing 1 - 4 of 4
  • Article
    Citation - Scopus: 1
    Production and Dispersion of Plasma Functionalized Carbon Nanotubes in Pan Fiber Spinning Solution With Different Surfactants
    (MMOB Tekstil Mühendisleri Odası, 2022) Kutlu, Bengi; Akşit, Aysun; Özyüzer, Lütfi; Yağmurcukardeş, Nesli; Selamet, Yusuf
    In this study, the distribution of plasma-functionalized multi-walled carbon nanotubes in polyacrylonitrile nanocomposite fibers produced by wet spinning method using different surfactants (Triton-X and sodium dodecyl sulfate) was investigated. Firstly, we produced CNTs by chemical vapor deposition (CVD) technique. Secondly, low-pressure plasma functionalization of CNTs was realized. Finally, nanocomposite polyacrylonitrile fibers doped by CNTs were obtained using wet spinning technique. Properties of produced carbon nanotubes, functionalized carbon nanotubes and nanocomposite polyacrylonitrile fibers were examined by the analyses of chemical composition, surface structure, structural and mechanical properties.
  • Article
    Study of the Effect of Various Chemical Polishing Treatments on Mbe-Grown Cdte/Gaas (211)b Heterostructures
    (Sakarya University, 2020) Bilgilisoy, E.; Özçeri, E.; Tarhan, E.
    A three-inch-diameter high quality CdTe thin film was grown on a GaAs (211)B substrate by molecular beam epitaxy (MBE) in ultra-high vacuum conditions. The CdTe/GaAs (211)B heterostructure was then cut into several sample pieces. A few as-grown sample pieces were subjected to chemical etching solutions which created etch pits on the surface. The scanning electron microscopy images of such samples were used to calculate the etch pit densities on the surface. In addition, several as-grown samples were subjected to chemical polishing treatments under different conditions to quantify the removal of O and Te-O structures from the surface. Atomic force microscopy was used to determine as-grown and polished surface morphology and the polish rate of chemical solutions. A study of the surface stoichiometry and the chemical composition of the as-grown and polished CdTe (211)B surfaces were carried out by using X-ray photoelectron spectroscopy. Bulk structural qualities of the as-grown and polished samples were studied in terms of the vibrational and phonon modes via confocal Raman spectroscopy. From a comparative analyses of the results, the best chemical polishing conditions for the MBE-grown CdTe (211)B heterostructure were determined. © 2020, Sakarya University. All rights reserved.
  • Article
    Investigation of Interactions of Acetylene Molecules With an Iron Nanowire and Its Effects on Mechanical Tensile Properties
    (Sakarya University, 2021) Aral, G.
    Understanding complex atomistic-scales interactions mechanisms of reactive acetylene (C2H2) molecules with reactive pure iron nanowires (Fe NWs) including its effects on the tensile mechanical properties of NWs is a crucial task in nanotechnology, especially having practical significance in the mechanical reliability, durability and stability. Therefore, we performed molecular dynamics (MD) simulations based on ReaxFF reactive force field interatomic potential model to investigate the interactions of C2H2 molecules with surface of cylindrical pure Fe NW and its fundamental effects on the tensile mechanical deformations properties of NWs at three different strain rates. Our results reveal that the chemical energetic reactions on the free surface of cylindrical Fe NW with C2H2 molecules in the gas phase form FexCyHz shell layer at temperature T=300 K. The presence of FexCyHz shell layer on the free surface of NW has a significant effect on the mechanical tensile deformation mechanism of the NWs. © 2021, Sakarya University. All rights reserved.
  • Book Part
    Citation - Scopus: 1
    Thz Sources and Detectors Fabricated From High Temperature Superconductors
    (Springer, 2021) Demirhan, Yasemin; Türkoğlu, Fulya; Altan, Hakan; Sabah, Cumali; Özyüzer, Lütfi
    High temperature superconductors have unique properties that can be useful in the THz region, single crystal constituted from superconducting CuO2-layers could sustain high voltages across the junctions and they are coupled through the intrinsic Josephson Effect this maintains the potential for very intense, coherent radiation which spreads over the THz gap. We investigated various experimental techniques to fabricate THz sources, bolometers and filters for efficient THz emission and detection. Rectangular mesa structures were fabricated on Bi2Sr2CaCu2O8-x (Bi2212) single crystal superconductors using standard e-beam lithography and Ar ion beam etching systems and an emitted power as high as 60 ?W at frequencies up to 0.85 THz was detected from micron sized continuous wave terahertz sources. We also fabricated bolometric microchips for THz detection purpose from Bi2212 single crystals. Bi2212 microchips detected the signals and response time were calculated, our results have clearly shown that Bi2212 single crystals are potential candidates for THz detection. The detection properties and sensitivity of bolometer chips can be further improved by integrating an antenna and filter structures. In order to investigate this we have fabricated metamaterial THz filters based on metals and YBa2Cu3Ox superconducting thin films with metal-mesh shape and a unique fourcross shape pattern. Both a THz time domain spectrometer and a Fourier transform infrared spectrometer (FTIR) were used to investigate the performance of these filters and the results were compared with simulations done with a commercially available electromagnetic simulation software. © Springer Nature B.V. 2021.