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ESMER, KADİR

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Subject: Natural Sciences ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Structural and dielectrical behavior of polypyrrole/huntite composites
    (2023-04-01) MADAKBAŞ, SEYFULLAH; ŞAHİN, NAZLICAN; ESMER, KADİR; Madakbaş S., Şahin N., Türk Z., Esmer K., Şen F.
    In order to characterize stable composites that will contribute to industrial applications, polypyrrole (PPy)/huntite composites were prepared by the physical method. Polypyrrole (PPy)/huntite composites were produced at various huntite concentrations (10, 20, 30, 40 wt.%). Polypyrrole/huntite was characterized by Fourier transform infrared spectroscopy (FTIR), Thermal Gravimetric Analyses (TGA), Differential Thermal Analyses (DTA), Scanning electron microscopy (SEM), and dielectrical properties were investigated by Impedance Analyzer at the room temperature. The FTIR spectra show that huntite mineral coordinate with polymers through carbonate groups. TGA results indicate the main cause of mass loss can be moisture in the samples and unreacted pyrrole monomer. SEM images show that the composites have a granular and spherical geometry. Dielectric measurements showed that at lower frequencies dielectric constants decrease exponentially with an increase in frequency and this behavior indicates that the effect of interfacial polarization becomes more predominant at a lower frequency.
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    Thermal and dielectric properties of flexible polyimide nanocomposites with functionalized nanodiamond and silver nanoparticles
    (2023-05-01) BİRTANE, HATİCE; MADAKBAŞ, SEYFULLAH; ESMER, KADİR; KAHRAMAN, MEMET VEZİR; Birtane H., Cigil A. B., Madakbaş S., Esmer K., Kahraman M. V.
    In the present study, amine groups were first modified to diamond and silver nanoparticles using APTMS to improve their homogeneous dispersion and compatibility in polyamic acid. Flexible polyimide nanocomposite films were successfully prepared by adding modified nanodiamond and silver nanoparticles to 4,4 \"-(1,3-phenylenedioxy) dianiline and benzophenone-3,3 \",4,4 \"-tetracarboxylic dianhydrides with different proportions. The effects of added amine-modified nanoparticles on dielectric constant and thermal stability were investigated. With SEM analysis, nanoparticles were homogeneously distributed on the polyimide surface and the presence of Si atom resulting from APTMS modification is clearly seen with the SEM-EDAX results. Considering the thermal resistance, the maximum decomposition temperature of the nano particle-free PI film was found to be 501 degrees C, while the thermal decomposition temperatures of the PI nanocomposite film that contains 1% m-Ag and the PI film that contains 5% m-ND, 502 degrees C and 505 degrees C, respectively. Also, it was seen that the dielectric constants of the prepared nanocomposite films that contain m-Ag NP decrease with increasing m-Ag NP ratio, and the dielectric constants of the films that contain m-ND increase with increasing m-ND ratio.
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    PublicationOpen Access
    Spectral investigation of Yb3+/Ho3+/Tm3+:Y2Si2O7 upconverting nanophosphors for the usage of temperature sensing
    (2023-02-28) ERDEM, MURAT; ESMER, KADİR; ERDEM M., ESMER K., Eryürek G.
    © 2023, Turkish Chemical Society. All rights reserved.Rare earth (Yb3+, Ho3+, Tm3+) yttrium disilicate phosphors were produced by sol-gel technique and heated at 1050 °C temperature. The sizes of the phosphors vary between 20-30 nm according to the images obtained from the Transmission Electron Microscope. The up-conversion (UC) emissions of the nanopowders were measured in the range of 500–900 nm wavelength under 950 nm laser excitation. A linear increase with power was observed in the emission intensity ratio depending on the laser excitation power. Using the FIR technique, the phosphor’s temperature was determined by the heating effect caused by the laser pump power. Due to the change in intensity ratio versus temperature, the temperature sensitivity at 428 K was calculated as 0.781x10-2K-1 and it was suggested that it can be used as a promising temperature sensor probe in photonic devices.