Yazar "Aytekin, Mehmet Ersin" seçeneğine göre listele

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    Change in Physical, Electrical and Magnetic Properties of Bi-2212 Superconducting Materials Co-Substituted with Nano-Sized Zinc and Sodium
    (Springer, 2024) Aytekin, Mehmet Ersin
    Enhancing the physical and morphological characteristics of BSCCO ceramics through element substitution or addition at varying rates can lead to an improvement in the superconducting properties of the material. Because of their special qualities, introducing nano-sized particles into the BSCCO system can produce very appealing outcomes. The investigation of substituting nano-sized zinc particles to calcium sites attempted to improve the inter-granular connections by settling the nanoparticles between the grains. In the presented study, the effect of substituting different amounts of nano-sized (< 100 nm) ZnO nanoparticles to Ca sites in the Bi-2212 superconductor system was investigated. The experimental data and initial composition had never been discussed in the literature before. Ceramic superconducting materials produced by the solid-state reaction method are carried out to X-ray powder diffraction measurements (XRD) for phase formation and crystal structure analysis, scanning electron microscope (SEM) measurements to determine their morpholic properties, resistivity temperature measurements (R-T) to determine for electrical properties and (M-H) measurements to determine for diamagnetic properties. XRD measurement results show that the main phase structure in all samples is the Bi-2212 high temperature phase. Although the diffraction patterns of the samples were similar in the XRD measurement results, the number of impurity phases increased in the sample containing nano-sized zinc substituted at x = 0.075. Plate-like grains were formed in the morphological structure of the samples, indicating the presence of Bi-2212 high temperature phases. Moreover, although the granular properties of the samples are similar to each other, the intergranular voids and angles increased in sample doped with x = 0.075 the nano-sized zinc ratio. All samples exhibit metallic behavior above the onset transition temperature. In substituted samples, although the highest onset transition temperature was observed in the nano-sized Zn substituted sample at x = 0.025, the highest superconductivity transition temperature value was observed in the nano-sized Zn-free sample compared to all samples. To characterize the magnetic properties, M-H measurements were performed as a function of magnetic field. All samples exhibited hysteresis behaviour, which is a characteristic feature of Bi-2212 high temperature superconducting materials. The critical current density performance of the samples was calculated from magnetization measurements using the Bean current model. Among the substituted samples, although improvements were observed in terms of magnetic properties in the sample containing nano-sized Zn at x = 0.025, the largest hysteresis area in the M-H results was observed in the sample that did not contain nano-sized Zn.
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    Improvement in electrical properties of Bi-2212 superconducting materials substituted with large-scale nano-sized tin
    (Springer Heidelberg, 2024) Aytekin, Mehmet Ersin; Akyol, Mustafa; Ozkurt, Berdan
    In the current work, the effect of nano-sized Sn (50 nm)/Sr partial replacement on the superconducting properties such as crystal structure, quality of intra- and intergrain boundary coupling, dc electrical resistivity, and dc magnetization in the Bi-2212 ceramic superconductors were investigated. Ceramic superconductors with nominal composition of Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy where x = 0.25, 0.30, 0.35 and 0.40 were prepared by solid-state reaction method and characterized by powder X-ray diffraction (XRD), dc electrical resistivity, scanning electron microscopy (SEM) and magnetic hysteresis (M-H) measurements. Phase examination of by XRD indicated that the doping of x = 0.25 ratio nano-sized SnO2 to the strontium sites improved the formation of the Bi-2212 high-temperature superconducting phase. SEM micrographs showed that the morphological structure of all samples consisted of plate-like grains, which were separated from each other by grain boundaries, indicating the Bi-2212 superconducting phase. The highest superconductivity transition temperature among the samples was measured as the T-c(onset) = 86 K at x = 0.25 in Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy. M-H loops of the Bi2Sr2-x(Sn)(x)Ca1Cu1.75Na0.25Oy sample at x = 0.25 ratio is larger compared to other examples, indicating improvement intergrain connectivity as well as enhanced flux pinning centers. In addition, the critical current (J(c)) values of the samples were calculated from M-H measurement using Bean's critical current model. The best J(c) values were obtained as 570 A/cm(2) at 15 K, which is a relatively high value for BSCCO superconductors with polycrystalline structure.
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    Nano Boyutta Kalay ve Sodyum Katkılı Bi-2212 Süperiletken Sisteminde Elektriksel Özelliklerin Matematiksel Formülasyonlarının Elde Edilmesi
    (2023) Aytekin, Mehmet Ersin; Yüce, Ali; Özkurt, Berdan
    Sunulan çalışmada, sodyum katkılı Bi-2212 süperiletken sisteminde stronsiyum sitelere nano boyutta kalay katkısının etkisi araştırılmıştır. Katı hal tepkime yöntemi kullanılarak üretilen süperiletken örnekler X-ışını kırınım analizi (XRD) ve özdirenç sıcaklık ölçümleri (ρ-T) ile karakterize edildi. Bunun yanında, özdirenç sıcaklık grafiğinden elde edilen veriler kullanılarak, nano boyutta kalay katkılama oranı ve süperiletkenlik geçiş sıcaklığı arasında teoriksel ilişki elde edildi. XRD ölçümü ile yapılan faz analizlerinde bazı safsızlık fazlarının oluşmasına rağmen tüm örneklerde temel faz yapısının Bi-2212 yüksek sıcaklık fazının olduğu tespit edildi. Özdirenç sıcaklık grafiğinden elde edilen bulgularda tüm örneklerin süperiletken davranış sergilediği gözlemlendi. Deneysel çalışma sonucunda, 0.05 oranında nano boyutta kalay katkısı içeren örnek diğer örnekler ile karşılaştırıldığında daha iyi süperiletkenlik özelliklere sahip olduğu belirlendi. Diğer taraftan, Matematiksel formülasyonların elde edilmesi işlemi Matlab ortamında eğri uydurma aracı kullanılarak gerçekleştirildi. Elde edilen matematiksel formülasyonlardan yararlanarak 0.682 oranında nano boyutta kalay katkısının optimum süperiletkenlik özelliklerini sağlayabileceği teoriksel olarak belirlendi.
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    Power Parameters Monitoring and Temperature Dependent Performance Analysis of Photovoltaic Panels
    (Malatya Turgut Ozal University, 2024) Şan, Uğurcan; Aytekin, Mehmet Ersin; Yüce, Ali
    Photovoltaic (PV) efficiency can be defined as the ability of solar cells to generate electricity at the highest rate from light energy. Today, there is a rapid transition from energy production based on fossil fuels, which have irreversible effects on the environment, to energy production with renewable energy sources. The discovery of photovoltaic systems in semiconductor technology and their use in energy production makes energy production with solar energy indispensable. However, the efficiency of PV panels is highly affected by environmental factors. In particular, overheating of the panels reduces the panel efficiency considerably due to the nature of the semiconductor material. On the other hand, another challenge in PV systems is to analyze the performance of the PV system under varying load conditions by considering many parameters such as sunlight intensity, direction/tilt, weather conditions, temperature, and panel at the same time. Therefore, in this study, an Internet of Things (IoT) based PV panel performance test system is designed to facilitate data collection for efficiency analysis of PV systems. Thanks to this system, remote monitoring of PV system performance is realized with IoT. The contribution of the cooling fans placed at specified locations on the panels to the efficiency of the PV panels was investigated. Overheating of PV panels is prevented by using cooling techniques. At the same time, performance data of both the system with and without cooling system were stored in the cloud environment. Thanks to the IoT application, the current, voltage and power values of the PV panel were monitored instantaneously. The data collected in the cloud in the uncooled and active cooling state of the PV panels were analyzed graphically. In the findings, it was observed that there was a 4.7% performance increase in PV panel efficiency using active cooling system.
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    Structural, electrical and magnetic properties of Au doped Bi-2212 superconductors
    (Pamukkale Univ, 2021) Gun, Esen; Ozkurt, Berdan; Aytekin, Mehmet Ersin; Ocakoglu, Kasim
    In this work effect of nano sized Au additions on the physical and magnetic properties of Bi-2212 phase with general formula of Bi(1.8)Sr(2)Ca(1.1)Oy+Au-x (x=0.0, 0.05, 0.1 and 0.2) are reported. The samples were prepared by solid state reaction method. Au element used in the material preparation process was obtained by reduction of HAuCl4 center dot 3H(2)O. The physical, morphological and superconducting properties of the samples have been characterized by XRD, scanning electron microscopy (SEM), dc electrical resistivity and magnetic-hysteresis loop measurements. It is observed that pure and Au added samples have plate like grain structure, indicating predominantly the formation of Bi-2212 phase. The results of dc electrical resistivity showed that the sample including x=0.2 HAuCl4 center dot 3H(2)O has the highest transition temperature (T-c) due to the formation of optimum hole concentration in copper oxide layers. Also, M-H measurements were carried out at T=10 K and T=25 K The Largest hysteresis loop due to its stronger coupling between grains was obtained on maximum HAuCl4 center dot 3H(2)O added sample.
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    The Influence of Nano-Sized SnO2 Doping on Physical and Magnetic Properties of the Bi2Sr2-x(SnO2)xCa1Cu1.75Na0.25Oy Superconductors
    (Springer, 2020) Aytekin, Mehmet Ersin; Ozkurt, Berdan
    In this study, we have investigated the effect of nano-sized SnO2 (50 nm) doping on the superconducting properties of Bi-2212 ceramics. In the first stage of the the experiment, the composition Bi2Sr2-xSnxCa1Cu1.75Na0.25Oy where x = 0, 0.05, 0.1 and 0.2 is selected due to the positive effect of sodium substitution on the grain sizes of the Bi-2212. X-ray diffraction results indicate that all the samples have considerable amount of Bi-2212 phases. Scanning electron microscopy (SEM) analysis of all samples clearly shows significant grain growth due to lower crystallization temperature formed by sodium. The lowest resistivity in the nano-sized SnO2-doped samples at 150 K is obtained for the sample of x = 0.05. The M-H hysteresis loops for all the samples have been measured within +/- 2 T externally applied magnetic field range at T = 15 and 25 K, respectively. The undoped and the sample with x = 0.05 SnO2 have both large M-H loops, indicating the improvement of flux pinning properties of the Bi-2212 as well as enhanced intergrain connectivity. However, the width of the hysteresis loop in samples including high (x > 0.05) SnO2 contents significantly decreased, indicating deterioration in superconducting properties of the Bi-2212 system. Additionally, the critical current densities (J(c)) of all the samples at 15 K are calculated from their hysteresis loop measurements by using Bean's critical state model. When compared with other samples, a slight increase in J(c) is obtained for x = 0.05 SnO2. The results indicate that the optimal contents of sodium (x = 0.25) and nano-sized SnO2 (x = 0.05) in the Bi-2212 system are effective for achieving enhanced superconductivity properties.
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    The role of post-annealing process on the physical, electrical and magnetic properties of nano-sized tin substituted Bi-2212 superconducting ceramics
    (Springer, 2024) Aytekin, Mehmet Ersin
    In the present work, post-annealing was applied to Bi2Sr1.80(SnO2)0.2Ca2Cu1.75Na0.25Oy samples prepared by the solid state reaction method at different temperatures of 730 degrees C, 780 degrees C and 830 degrees C for fixed dwelling time. Samples were analysed by XRD, SEM, R-T and M-H measurements. In XRD results, it was determined that despite the decomposition of the Bi-2212 phase after the post-annealing, the major phase in all samples was Bi-2212 phase. In the SEM measurement results, plate-like grain formation was observed in the microstructures of all samples. With the increase of post-annealing temperature, the sizes of plate-like grains decreased due to the decomposition in the Bi-2212 superconducting phase. In R-T graphs, an increase in the Tc was obtained in the sample with 730 degrees C post-annealing. In the M-H plots of all samples, hysteresis loop was obtained as the characteristic behaviour of Bi-2212 high transition temperature superconductors. Jc values were calculated from Bean model. In the sample with 830 degrees C post-annealing, as a result of the development of flux pinning centres, 1.219 X 106 A/cm2 of Jc value was obtained. Pinning Forces (Fp) were measured from Jc and B. In the sample with 830 degrees C post-annealing, the development of flux pinning mechanisms can be assisted by the secondary phases that arise from the decomposition of the Bi-2212 phase, leading to an increase in Fp.