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ESMER, KADİR

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ESMER

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KADİR

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Now showing 1 - 3 of 3
  • 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.
  • PublicationOpen Access
    Structural and Dielectric Properties of Eu3+, B3+ co-doped CoNb2O6 Ceramic
    (2024-04-01) EKMEKÇİ, METE KAAN; ESMER, KADİR; İLHAN M., EKMEKÇİ M. K., ESMER K.
    The boron co-doped CoNb2O6:xEu3+, yB3+ (x=1, 3, 6, 9, 12 mol%, y=10 mol%) ceramics were obtained by the molten salt method, which has advantageous properties such as short reaction time, low sintering temperature, improved homogeneity, and crystallinity. The ceramic samples were examined by structural and dielectric analyses. In X-ray diffractions, the orthorhombic columbite type CoNb2O6 structure was obtained, and also a minor EuNbO4 phase was detected with increasing Eu3+ doping concentrations. Additionally, increasing Eu3+ concentration led to a slight increase in crystallite size, and two theta peak shifts occurred towards higher angles associated with shrinkage in the lattice or reduction in the lattice constant. In SEM examinations, a slight increase was observed in grain sizes from 1 to 9 mol% Eu3+ in the range of 1-30 m, while some decrease occurred in grain sizes at 12 mol%, and there was an evident increase in plate-shaped and elongated grains. The dielectric constant (ε') of the ceramic samples increased with increasing Eu3+ concentration and reached approximately 35 and 0.24 at 20 Hz for 9 mol% Eu3+, respectively. The increase in dielectric loss with increasing Eu3+ was associated with an increase in ionic conductivity, in which Eu3+ substitution does not suppress oxygen vacancies or make them more ordered.
  • 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.