Yazar "Ozen, M. Kasikci" seçeneğine göre listele

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    Characteristic Properties of Dy-Eu-Ce Co-Doped ZrO2 Nanofibers Fabricated via Electrospinning
    (POLISH ACAD SCIENCES INST PHYSICS, 2016) Bezir, N. Cicek; Evcin, A.; Kayali, R.; Ozen, M. Kasikci; Esen, K.; Cambaz, E. B.
    Zirconium oxide (ZrO2) is one of the widely studied oxide materials because of its excellent electrical, mechanical and optical properties. In this study, undoped and Dy-Eu-Ce co-doped ZrO2 nanofibers were fabricated by electrospinning method and their crystal structure, surface morphology, optical properties, electrical and electronic properties, and chemical properties have been analyzed using X-ray diffraction, scanning electron microscope (SEM), UV/VIS spectrometer, four point probe technique ( FPPT) energy dispersive X-ray (EDX) measurements, respectively.
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    Investigation of Structural and Electrical Properties of (Bi2O3)1-x-y(CeO2)x(Eu2O3)y Electrolytes for Solid Oxide Fuel Cells
    (Polish Acad Sciences Inst Physics, 2019) Islek, Y.; Ozen, M. Kasikci; Kayali, R.; Ari, M.
    In the present study, CeO2 and Eu2O3 doped Bi2O3 composite materials for solid oxide fuel cells were investigated. (Bi2O3)(1-x-y)(CeO2)(x) (Eu2O3)(y) ternary systems (x = 0.01, 0.03, 0.05, 0.07, 0.09, 0.11 and y = 0.11, 0.09, 0.07, 0.05, 0.03, 0.01 dopant concentrations) were fabricated at different temperatures (650, 700, 750, and 800 degrees C) using conventional solid-state synthesis techniques. Characterization of these electrolyte samples were carried out by X-ray powder diffraction, differential thermal analysis/thermal gravimeter, and the four-point probe technique measurements. X-ray powder diffraction measurements showed that nearly all the samples have alpha+beta+gamma phase except the samples with tetragonal beta-phase sintered at 700, 750 degrees C and 750, 800 degrees C with the dopant ratios (x = 0.07, y = 0.05) and (x = 0.09, y = 0.03), respectively. Four-point probe technique measurements showed that the measured ionic conductivity of the stable samples vary in the range 1.05 x 10(-1)-4.76 x 10(-1) S/cm. Additionally, the activation energy values of the samples were calculated with the help of the Arrhenius equation adapted to the logs graphics versus 1000/T varying in the range 0.7799-0.8746 eV. This result shows that there is a good relationship between the activation energy values and conductivity values.
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    Synthesizing of (Bi2O3)(1-x-y)(Ho2O3)(x)( Dy2O3)(y) Electrolytes for Intermediate-Temperature Solid Oxide Fuel Cells
    (POLISH ACAD SCIENCES INST PHYSICS, 2016) Ozen, M. Kasikci; Kayali, R.; Bezir, N. Cicek; Evcin, A.
    In present study, Ho2O3 and Dy2O3 doped Bi2O3 composite materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) were investigated. (Bi2O3)(1-x-y)(Ho2O3)(x)(Dy2O3)(y) ternary systems (x = 0.11, 0.13, 0.15 and y = 0.01, 0.03, 0.05, 0.07) were fabricated using conventional solid-state synthesis techniques. The samples were characterized by means of X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential thermal analysis/thermal gravimeter, and the four-point probe technique. X-ray powder diffraction measurements indicated that all samples have the stable fluorite type face centered cubic (fcc) delta-Bi2O3 phase. Scanning electron microscopy micrographs of all of the samples showed that grain size distribution was uniform. Four-point probe technique measurements showed that the conductivity of the samples increase with increase of temperature. Additionally, it has been found that the maximum conductivity values of all samples fall in a range 8.4 4 x 10(-2)-4.60 x 10(-1) S cm(-1) and their conductivity values corresponding to the intermediate-temperature region vary in the range 1.65 x 10(-3)-2.30 x 10(-1) S cm(-1). The activation energy values of the samples were calculated from log sigma graphics versus 1000/T using the Arrhenius equation. It was found that there is a good agreement between the activation energy values and conductivity values.