Özlem CICEK | Iskenderun Technical University (original) (raw)

DOI:10.1016/j.cryogenics.2014.07.004 by Özlem CICEK

FEN BILIMLERI VE MATEMATIKTE Uluslararası Araştırma ve Değerlendirmeler, 2023

Slater-Pauling rule and Curie temperature of Co2-based Heusler compounds.

JOURNAL OF MATERIALS AND ELECTRONIC DEVICES, 2023

Besides many interesting features of MgB2, it is important for the green economy of the future th... more Besides many interesting features of MgB2, it is important for the green economy of the future that it allows systems that use L-Ne or L-H2 instead of cryogens; meanwhile as a light material, it can attract attention in terms of portable applications and especially space applications. MgB2 bulks and wires are produced by various processing techniques that can be categorized as either in-situ or ex-situ methods. Both have their own advantages and disadvantages. Therefore, the decision on which method to use should be evaluated according to the needs of the application. For the good inter-grain connectivity, in-situ production should be chosen but improved. Instead of high temperatures and long heat treatment duration, examining the effect of relatively lower and shorter times on the material was deemed necessary for the optimization of the in-situ method. For this reason, in this study, microstructural examination of bulk MgB2 samples produced by in-situ method at 625, 650 and 700 °C for 6 and 12 hours, was carried out. The samples microstructural properties were investigated by XRD and SEM measurements. XRD measurements were performed between 20° and 80° with step size of 0.02° from the pellet surface. The crystallographic refinement was simulated using the Full Prof software by the Rietveld method. Lattice parameter and cell volume, phase fractions were determined. The crystallite size is calculated from the XRD results using the Debye-Scherrer formula. Magnetic Tc,mag was determined as around 38,5 K from the magnetization measurement. The results provide guideline for further optimization of the microstructure of bulk MgB2 with enhanced properties.

Keywords: MgB 2 bulk and wire Boron powder XRD AC susceptibility Magnetization measurements a b s... more Keywords: MgB 2 bulk and wire Boron powder XRD AC susceptibility Magnetization measurements a b s t r a c t

DOI:10.1088/0953-2048/27/9/095016 by Özlem CICEK

DOI:10.1007/s10948-012-1952-z by Özlem CICEK

DOI:10.1016/j.matlet.2012.09.105 by Özlem CICEK

DOI:10.1016/j.cryogenics.2012.05.011 by Özlem CICEK

DOI:10.1016/j.jmmm.2012.02.064 by Özlem CICEK

DOI:10.1007/s10948-010-0945-z by Özlem CICEK

Measurements on Bi-2223 multifilamentary tapes covered on edges by nickel showed a substantial AC... more Measurements on Bi-2223 multifilamentary tapes covered on edges by nickel showed a substantial AC loss reduction (Gömöry et al. in Supercond. Sci. Technol. 22: 034017, 2009) and increasing critical current of the tape.

Papers by Özlem CICEK

Acta Physica Polonica A, Apr 1, 2023

In this work, pure and with 1, 3, 5, 10, and 15 wt% multi-walled carbon nanotube addition Bi2Sr2C... more In this work, pure and with 1, 3, 5, 10, and 15 wt% multi-walled carbon nanotube addition Bi2Sr2CaCu2O8+s glass-ceramic materials have been investigated in terms of thermal, structural, microstructural, electrical, and magnetic properties. Multi-walled carbon nanotubes with a purity of 96% were used to enhance electrical transport properties. Thermal properties have been examined using differential thermal analysis. According to the differential thermal analysis, the multi-walled carbon nanotube addition reduced the melting temperature and slightly increased the crystallization activation energy of the BiSrCaCuO material. X-ray analyses showed that all samples have tetragonal symmetry and did not change with addition, but a small change in the c-axis is observed. Scanning electron microscope analyses showed no significant morphological change. The effect of the additive on the resistivity measurements was found to be limited, and zero resistance temperature increased up to a level of 5 wt% addition and then decreased drastically for higher addition cases. The hole concentration of the samples was calculated, and it was found that there was a shift towards the over-doped region with the addition. For the transport critical current density measurements, the highest increase of about 30% was obtained for the sample with 5 wt% multi-walled carbon nanotube addition, but in high addition cases, significant losses were obtained. A similar situation occurred in magnetization versus magnetic field measurements, and the highest magnetization critical current density value obtained was 4.1 × 10 6 A/cm 2 at 4.2 K in the 5 wt% multi-wall carbon nanotube added sample. topics: multi-wall carbon nanotube, high-temperature superconductors, BSCCO glass-ceramic, BSCCO superconductors

Journal of Molecular Structure, Jul 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Acta Physica Polonica A, Oct 1, 2022

In this study, YBCO superconducting samples with the nominal composition of Y(Ba1−xMgx)2Cu3O 7−δ ... more In this study, YBCO superconducting samples with the nominal composition of Y(Ba1−xMgx)2Cu3O 7−δ , where x = 0.0, 0.5, 1.0, and 1.5, were prepared by the solid-state method to get better superconducting properties. Structural, electrical transport, and magnetic characterizations up to ±9 T applied fields were performed, including calculations of the upper critical field Hc2(0), irreversibility field µ0Hirr, activation energy U0(J, T, H), and pinning force Fp, and the obtained results were presented the first time for the Mg substitution to a Ba site in an optimally-doped YBCO superconducting system. It was found that the crystal parameters changed with the Mg substitution, but the crystal symmetry remained unchanged. Two impurity phases, Y-211 and MgO, were grown and became dominant at high substitution ratios. The superconducting properties of the samples deteriorated with the substitution of Mg; even high MgO substituted samples showed no superconducting properties. Deteriorations were also obtained in the properties Hc2(0), µ0Hirr, U0(J, T, H), and Fp. Two important points are thought to be responsible for these deteriorations. (i) MgO is not being able to be fully resolved in the matrix. Therefore, instead of Mg replacing with Ba, MgO remains in the impurity phase. As a result of this, the Ba concentration in the structure gradually decreases, and then the superconductivity is destroyed. (ii) The samples shift from the optimally doped region to the over-doped region due to the increase in hole concentration.

Bu proje,tek ve cok damarli Magnezyum Diborur (MgB2) superiletken surekliboru bukme ve doldurma (... more Bu proje,tek ve cok damarli Magnezyum Diborur (MgB2) superiletken surekliboru bukme ve doldurma (CTFF) yontemi ile tel yapim cihazinin tasarlanipgelistirilerek teknolojik oneme sahip altyapi olusturulmasi ve nano katkilamaile MgB2 superiletkeninin superiletkenlik ozelliklerininiyilestirilmesi ve fiziksel karakterizasyonu uzerinedir. MgB2superiletken tellerin uretimi icin tasarlanan bu yeni teknolojiningelistirilmesiyle, AC ve DC akim icin bircok cihazda kullanilan superiletkenmalzemelerin endustriyel uygulamalarina guclu bir ivme kazandiracagi dusuncesihedefimiz olmustur. Superiletken tel yapimi icin teknigini ilk olarakTurkiye’de uygulayan ve buna uygun cihaz tasarimini gerceklestiren, arastirmagrubumuz olmustur. Dunyadaki benzer ornekleriyle karsilastirildiginda bu cihazhem daha ekonomik hem de boyut olarak daha kucuktur. Ayrica, en dista bakirbulunduran cift kilifli tel cekme sistemimiz benzeri olmayan bir sistemdir. Buyeni tasarim ile tellerimizin termal soka maruz kalmasi sonucu superiletkenlikozelligini uzun sure muhafaza edebilecegine inanmaktayiz. Bu cihaz ile birliktePIT (Powder In Tube) teknigi de kullanilarak tek damarli ve cok damarli MgB2superiletken teller farkli cap ve uzunluklarda uretilmistir. Projemizinana hedeflerinden biri olan nano boyutta katkilamalar yapilarak MgB2superiletken numunesinin superiletkenlik ozelliklerinin iyilestirilmesi vefiziksel karakterizasyonlarinin yapilmasi amaciyla oncelikle tartaric asit (C4H6O6),silicon oil, succinic asit (C4H6O4) ve borcarbid (B4C) katkilamalari denenmis ve MgB2superiletkeninin superiletkenlik ozellikler uzerine etkisi arastirilmistir. Bukatkilamalara ek olarak ayni donem icerisinde Tubitak destekli 109T106 noluproje kapsaminda da Benzen (C6H6) , Toulene (C7H8),Etil-toluen (C9H12) carbon(C) ve silicon carbide (SiC) katkilamalari da denenmistir. Yapilankatkilamalar sonucunda MgB2 superiletkeninin superiletkenlikozelliklerine etkisi R-T, M-T,M-H olcumleri ve XRD , SEM analizleriyapilarak arastirilmistir. ABSTRACT This project has mainly focused onfabrication of the single and multi-filament Magnesium Boride (MgB2)superconducting wires by continuous tube filling andforming (CTFF) method, designation and development of the wire drawingmachine, and also improvement of the superconducting properties of MgB2superconductors by adding nanometer-sized particles. The fabrication of MgB2superconducting wires is a new technology, and we believe that thisproject will increase the technological applications of the superconductingwires used for all AC and DC devices. Our research group is the first at the designationof a wire drawing machine and production of the superconducting wires inTurkey. Our machine has also some advantages in comparison to the ones thatresemble it in the world with its smaller dimensions and low cost. However, wenote that the system with double cladding with outer copper (OFHC) is unique toour system. We believe that with this new design, the wires were lessvolnurable to the thermal shocks. Single and multi-filament MgB2 superconductingwires at different diameter and lengths were produced by this machine togetherwith PIT (Powder In Tube) technique. Physical characterizations and improvement ofthe superconducting properties of the MgB2 samples by dopingnano-sized particles are in the scope of this project. Thus, the nanoadditivessuch as tartaric acid (C4H6O6), silicon oil,succinic acid (C4H6O4), and boron carbide (B4C)were added in MgB2 samples and their influences on superconductingproperties of MgB2 samples were investigated by means of R-T,M-T, M-H measurements, and XRD, SEM analysis. In the same period of time, the nano additives benzene (C6H6),toulene (C7H8), etil-toluene (C9H12), carbon (C), and silicon carbide(SiC), supported by TUBITAK under the project number 109T106, were also studied in addition to this project.

Journal of Superconductivity and Novel Magnetism, Oct 2, 2010

ABSTRACT Measurements on Bi-2223 multifilamentary tapes covered on edges by nickel showed a subst... more ABSTRACT Measurements on Bi-2223 multifilamentary tapes covered on edges by nickel showed a substantial AC loss reduction (Gömöry et al. in Supercond. Sci. Technol. 22: 034017, 2009) and increasing critical current of the tape. Here we present a systematic study of this effect involving numerical simulations. The samples were prepared by deposition of Ni layer on commercial Bi-2223 tape. After measuring the critical current and the transport AC loss, cross-section photos are taken and the properties of nickel cover determined to be used in the calculations. We observed that with increasing Ni thickness the transport AC loss of the wire is decreasing in the high current region. In low current region because of the magnetic hysteresis in the Ni cover the transport AC loss of the Ni covered tapes are larger. Our calculations according to the method which is detailed in Gömöry et al. (Supercond. Sci. Technol. 22:034017, 2009) show good agreement with measurements.

Journal of Magnetism and Magnetic Materials, Oct 1, 2012

ABSTRACT The effect of aromatic hydrocarbon (benzene, C6H6) addition on lattice parameters, micro... more ABSTRACT The effect of aromatic hydrocarbon (benzene, C6H6) addition on lattice parameters, microstructure, critical temperature (Tc), critical current density (Jc) of bulk MgB2 has been studied. In this work only 2 mol% C6H6 addition was found to be very effective in increasing the Jc values, while resulting in slight reduction of the Tc. Jc values of 2 mol% C6H6 added MgB2 bulks reached to 1.83×106 A/cm2 at 15 K and 0 T. Microstructural analyses suggest that Jc enhancement is associated with the substitution of carbon with boron and which also results in the smaller MgB2 grain size. The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the Tc by carbon addition. We note that our results show the advantages of C6H6 addition include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C, and significant enhancement in Jc of MgB2, compared to un-doped samples.

Bu calismada; MgB2’ye ferromanyetik bir malzeme olan Fe3O4 %0-10 arasinda cesitli oranlarda katil... more Bu calismada; MgB2’ye ferromanyetik bir malzeme olan Fe3O4 %0-10 arasinda cesitli oranlarda katilarak superiletkenlik ozelliklerinde herhangi bir gelisme olup olmadigi incelenmistir. Hazirlanan numunelerin kristal yapisi XRD’si cekilerek incelenmistir. Bu sonuclara gore asil fazda bir degisme olmadigi gozlenmistir. Hazirladigimiz numunelerimizden elde ettigimiz XRD sonuclarina gore her bir numune icin ayri ayri orgu parametreleri hesaplanmis ve a=3,0840A ve c=3,5267 A olarak bulunmustur. Bu sonuclar literaturde MgB2 icin bulunan sonuclarla tutarlidir. Bu bilgi isiginda, numune hazirlanmasi asamasinda MgB2 ve Fe3O4 toz karisiminda kimyasal bir reaksiyon gerceklesmedigini soyleyebiliriz. Fe3O4 katkili her bir malzemenin dusuk ac alanlardaki davranislarinin tespiti ise Hac=80, 160, 320, 640, 1280 A/m’lik ac alanlari uygulanarak, sabit f=111 Hz frekansinda ve T=15–40 K sicaklik araliginda yapilmistir. Farkli oranda Fe3O4 eklenmesi ile hazirladigimiz numunelerden elde edilen ac alan bagimlilik olcumlerinden, normal durumdan superiletkenlige gecisin 38,6K civarinda gerceklestigi gozlenmistir. Sabit bir manyetik alan altinda degisik katkilama oranlari icin Tp degerlerinde bir kayma gozlenmezken, ayni numune icin uygulanan alan arttikca Tp degerleri daha kucuk degerlere dogru kaymistir. Fe3O4, maalesef amaclandigi gibi MgB2’nin tane iclerine homojen bir sekilde dagilmadi ve hatta hic girmedigi soylenebilir, daha cok tane sinirlarinda bulundugu tahmin edilmektedir. Bu ozelliginden dolayi superiletkenlik ozelliklerde sistematik bir iyilesme gozlenmedi. Bunu gidermek icin standart MgB2 ile baslamak yerine saf element Mg ve B ile nano parcacik ile numune hazirlamaya ihtiyac duyulmaktadirAbstract MgB2 is a promising superconductor and expected to replace conventional superconductors (for example, NbSn) being used in applications due to its low cost providing that its physical properties are enhanced. It is shown very recently that Boron is responsible for superconducting properties. MgB2 is classified as type II superconductor and flux dynamics must be controlled in order to enhance physical properties. In this work, we have added nano particles of Fe3O4 (FM) at various percentages from 0% to 10%. We have searched the effects of nano-particle content by using the characterization methods of XRD and ac susceptibility. Our XRD measurements show that the additions of Fe3O4 did not change the lattice parameters of pure MgB2. Therefore, we can say that there was not a chemical reaction between MgB2 and Fe3O4. According to our ac susceptibility measurements, we find the transition temperature as 38,6K. Under the same magnetic field, the magnitude of addition has not an effect on Tp. On the other hand, application of increasing magnetic field on the same sample decreased the Tp value gradually. Unfortunately, Fe3O4 did not spread homogeneously in MgB2. Moreover, Fe3O4 did not enter the lattice structure of MgB2. It has been envisaging that Fe3O4 is at the grain boundary. Because of that, there was not a systematic increase in the superconducting property of the samples. To get rid of this, samples may be prepared from the starting powders of Mg and B instead of MgB2 as the starting powder.

Journal of Superconductivity and Novel Magnetism, 2013

In this paper, we report the doping effects of succinic acid, C 4 H 6 O 4 (from 0 to 30 wt%) on t... more In this paper, we report the doping effects of succinic acid, C 4 H 6 O 4 (from 0 to 30 wt%) on the lattice parameter, critical temperature (T c), critical current density (J c), upper critical field (H c2), and irreversibility field (H irr) in MgB 2 superconductor. It was found that MgB 2 doped with 10 wt% C 4 H 6 O 4 and sintered at 900°C exhibited excellent J c above 10 4 A cm −2 at 5 K and 8 T. Impurity scattering due to C substitution, improved crystallinity and the least amount of MgO in 10 wt% doped sample improves J c very significantly. The MgO amount is rapidly increased in 20 and 30 wt% doped samples which causes a strong depression of J c , H c2 , H irr due to poor inter and intra-grain connectivity.

Cryogenics, 2012

The effects of annealing temperature on the in-field Jc and surface pinning in The effects of ann... more The effects of annealing temperature on the in-field Jc and surface pinning in The effects of annealing temperature on the in-field Jc and surface pinning in silicone oil doped MgB2 bulks and wires silicone oil doped MgB2 bulks and wires

Superconductor Science and Technology, 2014

ABSTRACT A binary magnesium diboride (MgB2) cable has been assembled by braiding six Nb/Monel she... more ABSTRACT A binary magnesium diboride (MgB2) cable has been assembled by braiding six Nb/Monel sheathed monofilament strands around a central copper stabilizer for improving the operational environment. The total critical current (Ic) of the braided cable is obtained by multiplying the Ic of six single wires, without any dissipation. In this work, various mechanical deformations, i.e., swaging, two-axial rolling, groove rolling, and cold high-pressure densification (CHPD) at 1.8 GPa have been applied to the 6-stranded cable to obtain additional densification. The highest critical current density at both 4.2 and 20 K has been achieved in this work through the CHPD treated cable due to higher filament mass density. The present results are promising in view of the cable, particularly in power applications at industrial lengths that pave the way to seeking an optimal protocol to meet a practical functionality.

Journal of Superconductivity and Novel Magnetism, 2010

Cryogenics, 2014

ABSTRACT We report a comparative study for bulk MgB2 superconductors and monofilamentary Ti/MgB2 ... more ABSTRACT We report a comparative study for bulk MgB2 superconductors and monofilamentary Ti/MgB2 wires as functions of the boron powder purity, average particle size of magnesium, and applied pressure. The structural and magnetic characterizations of the bulk samples were performed by means of XRD and AC susceptibility measurements, respectively. We found that the applied pressure did not cause any significant change on the onset transition temperature Tc,onset and transition width. This is also confirmed by the calculation of the lattice parameters. On the other hand, Tc,onset values were measured as 37.3K, 38.0K, and 38.6K for the samples prepared from the precursor boron powders with purities of 95.2%, ⩾ 95%, and > 98%, respectively. However Mg-particle size (Mg1: AlfaAesar Mg powder, avg. par. size:-325 mesh, purity: 99.8%; Mg2: SigmaAldrich Mg powder, avg. par. size: 20-230 mesh, purity: 98%) did not affect the Tc,onset but increasing the Mg particle size caused a significant broadening at the superconducting transition width for all precursor boron powder purity levels. Magnetization measurements showed that the critical current density of Ti/MgB2 wire prepared from AlfaAesar Mg powder (avg. par. size: -325 mesh) and Aldrich B powder (amorphous, purity ⩾ 95%) is greater than that of prepared by SigmaAldrich Mg powder (avg. par. size: 20-230 mesh) and Pavezyum B powder (amorphous, avg. par. size: 0,3 μm (max), purity > 98%) as 2.6 x 105 A/cm2 and 1.4 x 105 A/cm2 at T = 10K and μ0H = 0.5 T, respectively. In addition, SigmaAldrich Mg and Pavezyum B wire sample has a lower pinning force, Fp, value at each temperature.

Materials Letters, 2013

ABSTRACT We evaluate the effects of the mixing process between the starting materials on the stru... more ABSTRACT We evaluate the effects of the mixing process between the starting materials on the structural and superconducting properties of carbon-doped MgB2 wires. The critical current density, n-value, amount of MgO, and critical temperature are obviously dependent on the mixing process, while the microstructure, i.e., grain size, is not sensitive. In our study, the wet-mixing process in toluene enables more homogenous mixing between the starting materials, resulting in superior Jc and n-value.