Browsing by Author "Ozturk H."

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Effect of organic and inorganic fertilizers, or their combinations on yield and quality components of oil seed sunflower in a semi-arid environment
(2021-01-01) Sefaoglu F.; Ozturk H.; Ozturk E.; Sezek M.; Toktay Z.; Polat T.
Producers in semi-arid and highland regions have difficulty in increasing diversity in crop rotations due to unfavorable conditions imposed by cool temperatures, inadequate rainfall, and shorter growing periods. In such conditions, some cultural practices that increase productivity such as fertilization appear as a promising alternative. Fertilization and the form of fertilizer have a substantial influence on sunflower (Helianthus annuus L.) seed yield and quality. The objective of this study was to determine the responses of the oilseed sunflower to organic (vermicompost and leonardite) and inorganic (nitrogen and phosphorus) fertilizers, or their combinations in a semiarid conditions. To this end, the field research was carried out in 2017 and 2018 in Erzurum, Eastern Anatolia, Turkey. In this study, it was found that the organic and inorganic fertilizers alone and their combinations significantly affected all the plant parameters. The highest seed yield (4854 kg ha-1) and oil yield (2114 kg ha-1) were obtained from the combined use of nitrogen and vermicompost. Moreover, the use of vermicompost alone yielded the highest oil content (46.8%). According to the results of this study, combined applications of organic (vermicompost) and inorganic (nitrogen) fertilizers had the highest yield and agronomic characteristics in oilseed sunflower production; so, these applications can be recommended for the similar ecological conditions, that is, short growing season and high altitude.
Experimental and theoretical approaches for electrical, magnetic, micromechanical, and structural characterization of BSCCO ceramic superconductors
(2018-07-01) Safran S.; Ozturk H.; Bulut F.; Ozturk O.
This study investigates how the preparation and re-pelletization of BSCCO ceramic superconductors affects their structural, magnetic, electrical, and mechanical properties. Samples were prepared using conventional methods including the dry solid state (SS) reaction and wet ammonium nitrate (AN) precipitation, with three variations prepared for each technique. The fabricated samples were then characterized with X-ray powder diffraction (XRD) and scanning electron microscopy. The density, resistance vs. temperature characteristics, AC susceptibility vs. temperature characteristics, and magnetic hysteresis properties were measured. In addition, Vicker's microhardness was measured and revealed that all six samples exhibit the reverse indentation size effect (RISE). Microhardness modeling was also conducted. Calculations with Meyer's law, the Hays and Kendall model, and the proportional sample resistance model indicate that the samples are far from the plateau region, whereas the indentation-induced cracking model was consistent with the experimental results. The elastic modulus, Young's modulus, yield strength, and brittleness index were also calculated for each sample.
Mechanical, microstructural and magnetic properties of the bulk BSCCO superconductor prepared by two different methods
(2015-04-01) Safran S.; Kılıç A.; Kılıçarslan E.; Ozturk H.; Alp M.; Asikuzun E.; Ozturk O.
BSCCO bulk samples have been prepared by solid-state reaction and ammonium nitrate precipitation methods with Bi1.65Pb0.35Sr2Ca2Cu3O10±y stoichiometry. Structural, mechanical and magnetic characterizations of the samples were performed by the X-ray powder diffraction (XRD), the scanning electron microscopy (SEM), Microhardness measurements, AC susceptibility measurements. The XRD patterns showed that the diffraction peaks for our samples belong to the two main phase, namely 2223 and 2212 of the BSCCO. In this study we have focused on microhardness measurements to investigate the mechanical properties. Vickers microhardness, Young’s modulus and yield strength values were calculated separately for all samples. In addition to these, we calculated the load independent hardness values of samples. Experimental results of hardness measurements were analyzed using the Meyer’s law, proportional sample resistance (PSR) model, Elastic–Plastic deformation model (EPD) and indentation induced cracking (IIC) model. The critical transition temperature, phase purity, lattice parameter, surface morphology and crystallinity of the prepared bulk samples were compared with each other.
Superconducting and mechanical properties of the bulk Bi(pb)SCCO system prepared via solid state and ammonium nitrate precipitation methods
(2015-05-26) Safran S.; Kiliçarslan E.; Ozturk H.; Alp M.; Akdogan M.; Asikuzun E.; Ozturk O.; Kiliç A.
We have investigated the effect of preparation method on superconducting and mechanical properties of Bi(Pb)-2223 bulk samples using Bi1.85Pb0.35Sr2Ca2Cu3O10±y stoichiometry. Solid-state reaction and ammonium nitrate precipitation methods have been used for fabrication of the bulk samples. In addition, the effect of annealing time on BSCCO samples have been studied. Structural, electrical, magnetic and microhardness analyses of samples are performed by the X-ray powder diffraction (XRD), the Scanning Electron Microscopy (SEM), DC resistivity, AC susceptibility and Vickers microhardness test. The critical transition temperature, phase purity, surface morphology and crystallinity of the prepared bulk samples are compared with each other. Elasticity (E), brittleness (Bi), fracture toughness (KIC) and yield strength (Y) values are also determined according to annealing time, applied load and production parameters of materials.
The influence of re-pelletization and heat treatment on physical, superconducting, magnetic and micro-mechanical properties of bulk BSCCO samples prepared by ammonium nitrate precipitation method
(2017-12-01) Safran S.; Ozturk H.; Bulut F.; Ozturk O.
The influence of re-pelletization and annealing time on the structural, magnetic, electrical and mechanical properties of Bi-based high temperature bulk superconductor have been investigated. All samples used in this study have been prepared by a wet technique denoted as ammonium nitrate precipitation method. The samples have been characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), resistance vs. temperature (R-T), magnetic hysteresis (M-H) and hardness vs. applied load (Hv-F) measurements. Bi-2223 and Bi-2212 peaks as major phases have been observed with small amounts of impurities from XRD results. The microstructures of most samples show a plate-like granular form. The grain sizes have been investigated by SEM and XRD. The critical transition temperature (Tc) has been obtained from resistivity measurements in the range of 99–110 K, depending on the annealing time and re-pelletization. The calculated maximum critical current density (Jc), using Beans’ model, is around 12,000 A/cm2 at 10 K ∼ 0.2 T. Moreover, all prepared samples exhibit reverse indentation size effect (RISE) behavior and hardness increased with re-pelletization according to results obtained from mechanical measurements.