Browsing by Author "Akcan D."
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Scopus Enhanced mechanical properties of yttrium doped ZnO nanoparticles as determined by instrumented indentation technique(2018-06-15) Kaya S.; Akcan D.; Ozturk O.; Arda L.Yttrium doped (1, 3 and 5 wt%) zinc oxide nanoparticles were synthesized via sol-gel process. The phase, structural and mechanical properties were investigated using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and micro hardness based on indentation technique. The lattice parameters and grain sizes of the samples were calculated from the XRD data. As the lattice parameters increased, the grain sizes decreased dramatically, resulting in more grain boundaries and strong grain connectivity in the ZnO microstructure. Load-depth curves were obtained by applying indentation loads in the range from 400 to 2000 mN at room temperature. As the Y concentration increased, a significant increase was observed in the hardness values computed from loading-unloading curves using the Oliver and Pharr method. The indentation modulus of the samples reached a saturation value for 3% Y and then decreased as the doping rate increased. Moreover, the crack formation around the indent on the sample surface was examined by electron microscopy and was identified as radial/median type. The fracture toughness of the samples was calculated using the Vickers indentation fracture method. Increased fracture toughness values confirm that ZnO nanoparticles are mechanically strengthened by Y doping.Scopus Preparation, structural and micromechanical properties of (Al/Mg) co-doped ZnO nanoparticles by sol–gel process(2015-10-22) Asikuzun E.; Ozturk O.; Arda L.; Akcan D.; Senol S.; Terzioglu C.Zn0.90Mg0.10−xAlxO (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.10) nanoparticles were prepared by using sol–gel technique. The effects of Al and Mg doping on the structural and mechanical properties were investigated by using X-Ray diffraction (XRD), scanning electron microscopy (SEM) and digital micro-hardness tester, respectively. The grain size, a and c lattice parameters and morphology of nanoparticles were characterized by XRD and SEM measurements. The grain sizes of Al/Mg co-doped ZnO nanoparticles were also calculated by Scherrer–Warren equation. a and c lattice parameters are calculated from XRD peaks. According to the results it was observed that the grain sizes increased with increasing the Al doping. c lattice parameter partially decreased with Al doping. The experimental results of hardness measurements were analyzed using Meyer’s law, proportional specimen resistance model, elastic/plastic deformation model, and Hays–Kendall (HK) approach. It was observed that HK approach is the most successful model for the micro-hardness analysis of Al/Mg co-doped ZnO materials.Scopus Structural and mechanical properties of (Co/Mg) co-doped nano ZnO(2015-06-01) Asikuzun E.; Donmez A.; Arda L.; Cakiroglu O.; Ozturk O.; Akcan D.; Tosun M.; Ataoglu S.; Terzioglu C.The (Co/Mg) co-doped ZnO systems (ZnMgCoO) were synthesized as polycrystalline nanoparticles using the sol-gel technique. The effects of Co/Mg co-addition to the structural and mechanical properties of ZnO nanoparticles were investigated. Microstructural properties, such as phases, crystal structures and grain sizes are characterized by using X-Ray Diffraction (XRD) analysis and Scanning Electron Microscope (SEM). The microhardness values of the samples were evaluated by the Vickers tester. In the samples of the Co>Mg ratio, Indentation Size Effect (ISE) behaviors were observed. On the other hand, in the samples of the Mg>Co ratio, Reverse Indentation Size Effect (RISE) was observed. These were analyzed in detail utilizing the models for materials hardness analysis found in literature.Scopus Structural and mechanical properties of ZnMgO nanoparticles(2014-01-10) Tosun M.; Ataoglu S.; Arda L.; Ozturk O.; Asikuzun E.; Akcan D.; Cakiroglu O.This study reports the effect of annealing temperature on the structure and mechanical properties of Zn0.95Mg0.05O bulk samples by using digital Vickers microhardness tester, X-ray diffraction analysis, scanning electron microscopy and electron dispersive X-ray measurements. The samples were prepared using Zn and Mg based alkoxed by the sol-gel technique and annealed at various temperatures (500, 600, 700 and 800°C). Vickers microhardness, elastic modulus, yield strength and fracture toughness values of Zn0.95Mg0.05O bulk samples were separately calculated and compared with each other. The experimental results of hardness measurements were analyzed using Meyer's law, Proportional Specimen Resistance (PSR) and Elastic/Plastic Deformation (EPD) models and Hays-Kendall (HK) approach. Finally, it was seen that HK approach is the most successful model for the microhardness analysis of these materials. © 2013 Elsevier B.V.