Yazar "Evcin, A." seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Characteristic Properties of Dy-Eu-Ag co-Doped TiO2 Nanoparticles Prepared by Electrospinning Processes(POLISH ACAD SCIENCES INST PHYSICS, 2015) Evcin, A.; Bezir, N. C.; Kayali, R.; Kasikci, M.; Oktay, A.TiO2 with high photoactive wide band gap energy semiconductor has been studied intensively for its attractive applications as photo catalyst and solar cell. TiO2 has three kinds of different crystal structures; anatase, brookite and rutile. TiO2-nanoparticles could become valuable light emitting materials when they are doped with highly luminescent rare earth ions. In this study, Dy-Eu-Ag co-doped TiO2 nano particles were prepared by electrospinning method. The crystal structures of nanofibers were determined X-Ray Diffraction device (XRD), morphology of the samples were analyzed by scanning electron microscope (SEM), and the optical properties of the samples were determined by ultraviolet/visible spectrometer (UV/VIS) measurements. Electrical and electronic properties of the sampled were determined using the data obtained from four point prob technique (FPPT).Öğe 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.Öğe Comparison of Five-Layered ZrO2 and Single-Layered Ce, Eu, and Dy-Doped ZrO2 Thin Films Prepared by Sol-Gel Spin Coating Method(Polish Acad Sciences Inst Physics, 2017) Bezir, N. Cicek; Evcin, A.; Kayali, R.; Ozen, M. K.; Esen, K.In order to investigate the influence of the number of layers on the properties of ZrO2 thin films, we prepared one pure ZrO2 film sample with five layers and Ce, Eu, and Dy-doped ZrO2 samples with single layer, by spin-coating sol gel-method. The crystal structures of thin films were determined using X-ray diffraction, morphology of the samples was analyzed by scanning electron microscopy, and the optical properties of the samples were determined by ultraviolet/visible absorbance measurements. The results of these measurements have shown that the concentration of the dopants and the thickness of thin film layers play a vital role in the physical, chemical, and optical properties of the pure and doped ZrO2 thin films.Öğe Comparison of Pure and Doped TiO2 Thin Films Prepared by Sol-Gel Spin-Coating Method(Polish Acad Sciences Inst Physics, 2017) Bezir, N. Cicek; Evcin, A.; Kayali, R.; Ozen, M. K.; Balyaci, G.In this study, using spin-coating sol-gel method we fabricated TiO2 thin films, doped with different concentrations (1, 2, and 3 mole %) of Ce, Dy, and Eu. Characterization of the prepared samples was performed by means of the X-ray diffraction, scanning electron microscopy, ultraviolet visible absorption, and differential thermal and thermo gravimetric analysis. X-ray diffraction measurements have shown that in Eu and Dy-doped samples crystal structure consists of mixed rutile and the dominant anatase phases, however the Ce doped samples consist of anatase phase only. Scanning electron microscopy images have revealed that while average thin film thickness of the Dy-doped samples decreases with increasing concentration of Dy, the average film thicknesses of samples doped with Ce and Eu increases with increasing concentrations of these dopants. Ultraviolet visible absorption spectroscopy measurements have shown that while absorbances of the samples doped by 1 and 2 mole % of the dopants have nearly similar properties, these properties differ from each other for 3 mole % of the dopants. Finally, differential thermal and thermo gravimetric analyses have shown that the chemical reactions and weight losses of the samples have occurred at the expected temperatures.Öğe Effect of Layer Thickness on I-V Characteristics of GaInP Nanofibers Fabricated by Electrospinning on n-Si Substrates(Polish Acad Sciences Inst Physics, 2017) Bezir, N. Cicek; Evcin, A.; Okcu, H.; Kayali, R.; Kaleli, M.; Aldemir, D. A.GaInP nanofibers were formed on n-Si substrates by electrospinning method, using constant voltage (25 kV), height (6 cm), and flow rate (0.3 ml/h) during various process times (of 10, 20, 25 minutes). Characterization of the prepared samples was performed by X-ray diffraction, differential scanning calorimetry/thermal gravimetric analysis, scanning electron microscopy, and energy dispersive X-ray spectrometry. Furthermore, the current-voltage measurements of the GaInP/n-Si samples have been carried out. The obtained results show that I - V characteristics of all GaInP/n-Si samples fabricated with three thicknesses of GaInP layers are rather in a good agreement with the theory and that they exhibit rectifying properties.Öğe 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.
