Browsing by Author "Terzioglu R."

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Effect of doping on microstructure and optical properties of ternary structure of Zn1−x−yBxCyO (B=Cu, C=Co) nano thin films
(2020-12-01) Asikuzun E.; Ozturk O.; Terzioglu R.; Arda L.; Terzioglu C.
We report the results of an in depth study of optical and microstuctural properties of thin films of Zn1−x−yCuxCoyO system (x = 0,00 and 0.02, y = 0.00, 0.01, 0.02, 0.03, 0.04. and 0.05) which are grown by the sol–gel method. We have performed differential thermal analysis, and thermo gravimetric analysis/difference thermogravimetric analysis, x-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, atomic force microscopy and UV–VIS spectrophotometer experiments. We have found that all of the studied samples are in hexagonal wurtzite structure and oriented along the (002) direction with a very weak signal for the (101) reflection. We have also found that the lattice parameter c increases with doping. All the films showed wrinkle network structure with nano-sized crystals and the grain size was observed to decrease with increasing Co doping. The bandgap was found to decrease from 3.28 to 3.22 eV with doping. All the above results will be discussed in detail.
The influence of boron doping on the structural and mechanical characterization of ZnO
(2019-08-15) Senol S.; Terzioglu R.; Ozturk O.
In this study, we have reported the structural and mechanical properties of B-doped ZnO (Zn1-xBxO, x = 0.00, 0.05, 0.07, 0.09, 0.11)by using XRD, SEM, EDS and static Vickers micro-hardness measurements. All nanopowder samples were prepared by hydrothermal method. From the XRD measurements, we have found that all the samples crystalize in hexagonal wurtzite structure and crystallite sizes were found to be 61.50, 36.97, 36.65, 36.59 and 34.85 nm for x = 0.00, 0.05, 0.07, 0.09, 0.11 samples, respectively. From the SEM measurements, the irregular appearance and size distribution of the particles were observed for all samples. The chemical composition of Zn1-xBxO nanopowders were investigated by EDX spectroscopy. Zn,O and B peaks are clearly seen and the content of Zn, O and B are consistent with preparation of samples. From the load dependent indentation diagonal length measurements, load dependent (apparent)hardness, elastic modulus, yield strength, and fracture toughness values of the samples were computed. The hardness values increase with increasing the boron content and the applied load. In addition, the apparent hardness values were analyzed by using the various theoretical models to evaluate the load independent (true)hardness values. The IIC model was found to be sufficient for our investigations. The possible reasons for the observed changes in mechanical, structural properties due to B-doping in ZnO were discussed.
The structural and dynamic nanohardness properties of yttrium substituted layered (La, Ca)3Mn2O7 manganites
(2023-01-01) Koc N.S.; Terzioglu R.; Ozturk O.; Terzioglu C.
This study devotes the structural and dynamic nanohardness properties of yttrium (Y) substituted within La1.4Ca1.6Mn2O7 manganites. XRD, SEM, EDS and dynamic nanohardness measurements are carried out to determine the structural properties such as grain sizes, impurity phases, crystallite sizes, average strain, and surface morphologies. The obtained results were compared with other rare-earth (RE) substituted double-layered lanthanum manganites published in the literature that have the same A-site radius. The lattice parameters are not affected substantially by the Y addition while the average grain size is significantly different from the other RE-substituted samples. The mechanical properties obtained from the dynamic micro-hardness tests such as the contact depth, area of the indent imprint, stiffness, creep, apparent hardness, reduced elastic modulus and the elastic recovery ratio (ERR) are calculated for the Y-substituted sample and compared with previously published studies. Different models are applied to determine the measured and true micro-hardness values. The microstructural and mechanical properties of Y-substituted double-layered manganites are discussed in detail.