Highly regular hexagonally-arranged nanostructures on Ni-W alloy tapes upon Irradiation with ultrashort UV laser pulses

This article belongs to the Special Issue Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif.Nickel tungsten alloy tapes (Ni—5 at% W, 10 mm wide, 80 µm thick, biaxially textured) used in second-generation high temperature superconductor (2G-HTS) technology were laser-processed in air with ultraviolet ps-laser pulses (355 nm wavelength, 300 ps pulse duration, 250–800 kHz pulse repetition frequency). By employing optimized surface scan-processing strategies, various laser-generated periodic surface structures were generated on the tapes. Particularly, distinct surface microstructures and nanostructures were formed. These included sub-wavelength-sized highly-regular hexagonally-arranged nano-protrusions, wavelength-sized line-grating-like laser-induced periodic surface structures (LIPSS, ripples), and larger irregular pyramidal microstructures. The induced surface morphology was characterized in depth by electron-based techniques, including scanning electron microscopy (SEM), electron back scatter diffraction (EBSD), cross-sectional transmission electron microscopy (STEM/TEM) and energy dispersive X-ray spectrometry (EDS). The in-depth EBSD crystallographic analyses indicated a significant impact of the material initial grain orientation on the type of surface nanostructure and microstructure formed upon laser irradiation. Special emphasis was laid on high-resolution material analysis of the hexagonally-arranged nano-protrusions. Their formation mechanism is discussed on the basis of the interplay between electromagnetic scattering effects followed by hydrodynamic matter re-organization after the laser exposure. The temperature stability of the hexagonally-arranged nano-protrusion was explored in post-irradiation thermal annealing experiments, in order to qualify their suitability in 2G-HTS fabrication technology with initial steps deposition temperatures in the range of 773–873 K.The authors gratefully acknowledge the financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) ARDEB 1001 (project number: 117F399) program, the Spanish MCIN/AEI/10.13039/501100011033 (project PID2020-113034RB-I00), the LaserImplant project (European Union’s Horizon 2020 research and innovation program under grant agreement No. 951730) and from Gobierno de Aragón (research group T54_20R).Peer reviewe

PRODUCTION OF Bi-BASED HIGH TEMPERATURE VANADIUM DOPED SUPERCONDUCTORS AT VARIOUS RATIONS, INVESTIGATION OF THEIR STRUCTURAL AND PHYSICAL PROPERTIES

Bu çalışmada, Bi2-xVxSr2Ca2Cu3O10+δ (x= 0,1, 0,3 ve 0,5) süperiletken malzemesi, cam seramik metodu kullanılarak üretildi. Elde edilen cam numuneler 840 oC'de ısıl işleme tabi tutuldu. Örneklerin termal analiz (DSC, TGA), taramalı elektron mikroskobu (SEM), x-ışını toz difraksiyonu (XRD), ve Hall etkisi ölçümleri 60-300 K aralığındaki farklı sıcaklıklarda ve farklı manyetik alanlarda (0,2, 0,6, 1,0 ve 1,4 T) karakterize edildi. X-ışını analizi ile yapıların iki ana fazı (BSCCO 2212 ve 2223) olduğu belirlendi ve elde edilen verilerden bu yapılara ait örgü parametreleri hesaplandı. Örneklerin kristalleşme kinetikleri DSC tekniği ile araştırıldı. Kinetik parametreleri, izotermal olmayan JMAK metodu kullanılarak farklı ısıtma hızlarında hesaplandı. Kissinger metodu kullanılarak ekzotermik pikler için aktivasyon enerji değerleri 357,202 – 390,66 kJ/mol aralığında bulundu.In this study, glass-ceramic Bi2-xVxSr2Ca2Cu3O10+ δ (x= 0,1, 0,3 and 0,5) superconductors were prepared by using the melt-quenching method. The glass samples produced were treated by heat at 840 oC. These samples were characterized by thermal analysis (DSC-TGA), scanning electron microscopy (SEM), x-ray powder diffraction (XRD) techniques, and also by Hall effect measurements at different temperatures in the range 140-300 K under different applied magnetic fields, 0,2, 0,6, 1,0 and 1,4 T respectively. Two main phases (BSCCO 2212 and 2223) were observed in the x-ray data and the values of the lattice parameters were in quite agreement with the known values for 2212 and 2223 phases. Crystallization kinetics of the samples were investigated with the help of DSC technique. The kinetic parameters were also determined via non-isothermal JMAK method for different heating speed applied the samples. Besides, the activation energies for exothermic peaks were found as in the range of 357,202 - 390,66 kJ/mol, by using Kissinger metho

CVD Yöntemi ile Karbon Katkılanmış Bor Kullanılarak Üretilen MgB2 Süperiletkeninin Yapısal ve Manyetiksel Özelliklerine Sıcaklık Etkisinin İncelenmesi

Carbon, which is known to play a improvement role on the superconductivity properties of MgB2, was doped into MgB2 by CVD (chemical vapor deposition) method, and the change of structural and magnetic properties observed in MgB2 in relation to the change of reaction temperature was investigated. In this context, in the sample preparation step, amorphous nano boron powders with carbon added by chemical vapor deposition method were mixed with magnesium powders at certain mass ratios and sintered at four different temperatures (700-800- 900-1000 0C) with the classical solid state reaction method and converted into carbon-added MgB2 samples. SEM photographs of amorphous nano-boron powders with carbon added were taken and subjected to elemental analysis. The structural and magnetic properties of the samples obtained were examined. X-ray diffraction graph, magnetization values and Magnetic Field-Magnetic Moment (M-H) graphs of the samples obtained by XRD method and the critical current density values with Bean Method were found and Magnetic Field-Critical Current Density (Jc-H) graph was created. It was determined that, in all the samples obtained, the MgB2 superconductor structure was formed and the carbon structures included in the structure caused changes in the lattice parameters due to the ion radius difference, that fracture occurred in the magnetization curve of the sample prepared by sintered at 1000 0C due to the intense impurities caused by the phase transitions due to the high temperature, in samples prepared at low temperatures, and that magnetization curves that could not expand sufficiently were observed, flux jumping occurs in the magnetization curve and this also affected the critical current density. In addition, the change in the critical current density value from 7.0x103 A/cm2 to 2.8x104 A/cm2 showed that the reaction temperature was an effective parameter on the experimental results. As a result of the examinations, when compared between the 4 different sintering temperature values used, it was found that the sintering temperature of 900 0C was the temperature at which the best physical results were obtained in MgB2

Investigation Of Microhardness Properties Of MgB2 Produced By Using Carbon Doped Boron By CVD Method

In this study, magnesium diborite which is obtained with boron element which is of strategic importance for our country and which has a very wide usage area in technological terms, is produced by using carbon doped boron obtained by chemical vapor deposition method. First of all, amorphous nano boron powders were doped with CVD method at 700 oC for 90 minutes under the source of ethylene hydrocarbon and inert gas flow. The amorphous nano boron powders doped in carbon were mixed with magnesium powders weighed in certain stoichiometric proportions in an automatic mixer. The mixture was weighed in 2,5 gs and converted into 4 tablets by manual pressing method. Each tablet was wrapped in zirconium foil and sintered under closed argon gas at temperatures of 700-800-900 and 1000 oC. Structural and mechanical properties of the obtained samples were investigated. According to the results of the analysis, it was seen that the characteristic peaks of MgB2 were predominant in all samples and the best explaining micro hardness properties of the samples were Meyer approach and IIC (Indentation-Induced Cracking) approach. In addition, RISE (Riverse Indentation Size Effect) behavior was detected in all samples

Bi-Ga Kısmi Yer Değiştirme Etkisinin Manyetik, Mekanik ve Mikroyapısal Özellikler Bi(1,8-x)Pb0,2GaxSr2CaCu2Oy Süperiletken Üzerinde İncelenmesi

BSCCO 2212 süperiletken sistem, ekleme ve kısmi değiştirme yöntemleri nedeniyle açık bir yapıya sahip olduğundan birçok çalışma yapılmış ve makaleler yayınlanmıştır. Bu çalışmada, BSCCO 2212 süperiletkeninde belirli bir oranda Bi-Ga kısmi yer değiştirmesi yapılarak Ga oranı artırılarak elde edilen örneklerin duyarlılığı ölçülerek Ga'nın yapının süperiletkenliğine etkisi araştırılmıştır. Her numunenin mekanik özelliklerini incelemek için Vickers mikro sertlik ölçümleri kullanıldı. Numunelerin yapısal özelliklerini belirlemek için x-ışını kırınımı (XRD) analiz sonuçları değerlendirildi ve taramalı elektron mikroskobu (SEM) görüntüleri ile kristal yapı oluşumları gözlemlendi

The effect of PbO and Se in different ratios on thermal properties of Bi2Sr2Ca1Cu2Ox BSCCO glass ceramic system

Bu çalışmada Bi2Sr2Ca1Cu2Ox (BSCCO) sistemine farklı oranlarda PbO ve Se katkılanması sonucu ısıl özelliklerinin nasıl değiştiği araştırılmıştır. Numunelerin ısıl özellikleri Diferansiyel Termal Analiz (DTA) cihazı kullanılarak belirlenmiştir. DTA ölçümlerine göre cam geçiş sıcaklığı (Tg), 733-749 K, kristalleşme pikinin başlangıç sıcaklığı (Tc), 739-759 K, kristalleşme pikinin tepe noktasının sıcaklığı (Tx), 746-766 K aralığında bulunmuştur. Aktivasyon enerjisi değerleri Kissenger, Takhor ve Augis-Bennett metotları ile hesaplanmıştır. Sonuçta aktivasyon enerji değerlerinin PS05 numunesi dışında, katkı miktarının artışıyla beraber arttığı belirlenmiştir. Ayrıca ısıl kararlılık parametresi değerleri Mahadevan eşitliği kullanılarak hesaplanmış ve PS01 numunesi en kararlı numune olarak bulunmuşturIn this study, thermal properties of Bi2Sr2Ca1Cu2Ox (BSCCO) doped PbO and Se in different ratios has been investigated. The glass transition temperature (Tg), the temperature of crystallization initiation (Tc) and the peak temperature of crystallization peak (Tx) values according to DTA measurements were obtained as 733-749 K, 739-759 K and 746-766 K, respectively. The thermal properties of the samples were determined by Differential Thermal Analysis (DTA). The activation energy values were estimated by using the Kissenger, Takhor, and Augis-Bennett methods, and found to increase with the increasing the amount of incorporation, except PS05 sample. In addition, the thermal stability parameters were calculated by using Mahadevan equality. The PS01 sample is found to be the most stable sample according to the calculation

The Effect of PbO and Se in Different Ratios on Thermal Properties of Bi2Sr2Ca1Cu2Ox BSCCO Glass Ceramic System

In this study, thermal properties of Bi2Sr2Ca1Cu2Ox (BSCCO) doped PbO and Se in different ratios has been investigated. The glass transition temperature (Tg), the temperature of crystallization initiation (Tc) and the peak temperature of crystallization peak (Tx) values according to DTA measurements were obtained as 733-749 K, 739-759 K and 746-766 K, respectively. The thermal properties of the samples were determined by Differential Thermal Analysis (DTA). The activation energy values were estimated by using the Kissenger, Takhor, and Augis-Bennett methods, and found to increase with the increasing the amount of incorporation, except PS05 sample. In addition, the thermal stability parameters were calculated by using Mahadevan equality. The PS01 sample is found to be the most stable sample according to the calculations