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1.
The stress–strain properties of Bi-2223 tapes directly relate to its applications, but have not been systematically studied
yet. Three tapes sheathed by Ag and Ag alloys were manufactured for the study of stress–strain. X-ray diffraction analyses
were used to determine the amorphous and Bi-2223 phases for the three tapes before and after sintering. Tensile experiments
were performed to study the stress–strain properties as well. Micro-morphologies of the three tapes were observed and recorded
by scanning electron microscopy. The experimental results show green tapes with a linear stress–strain relation. It is suggested
that this relation comes from the sheathed metal’s properties. The mechanical properties of Ag/Mg sheathed tapes are like
those of a rigid body, which do not present plasticity and elasticity. The phenomena of outgrowth and bridges were observed
in Ag and Ag/Sb sheathed tapes. Also, Ag and Ag/Sb sheathed tapes showed abnormal stress–strain properties, which were subjected
to micro-cracks existing in the sheathed metals and imperfections of Bi-2223 crystals. 相似文献
2.
W. M. Chen Quan Li Weiyan Chen H. Y. Ling S. S. Jiang 《Journal of Superconductivity》2004,17(3):481-485
Outgrowths of Bi-system superconducting multifilament tapes were known as an imperfect that could increase ac-current loss. To approach this problem sintering temperature dependent of outgrowth was studied and experimental results were reported in this text. Tapes in the experiments were sheathed with pure silver and silver alloys and carefully treated. Critical current I
c of the sintered tapes was measured at 77 K. Compound phases in tapes were determined by analysis of X-ray powder diffraction. Outgrowths of the tapes were observed and studied by Scanning Electron Microscope. Experimental results showed that outgrowths changed when sintering temperatures increased. It was found that the best sintering temperature for Ag sheathed tape was 840°C, and that for Ag/Mg and Ag/Sb sheathed tapes was lower than 835°C. 相似文献
3.
To improve on present critical current (J c) performance, multifilamentary Ag/Bi-2223 tapes with a large range of reduction rates were manufactured. The relative core mass density D was calculated, dependent on the measured geometric dimensions of the tapes. Experimental results, D vs. J c, D vs. maximum pinning force density F max , and D vs. irreversible magnetic field B irr, are quantitatively formatted. In particular, the magnetic field dependence of J c is critically dependent on its core density. If the core density increases by 10%, J c of the tapes in this experiment is enhanced by as much as 100%. Therefore, in the present state of the technological process for manufacturing Ag/Bi-2223 tape, increasing the core density is clearly a significant strategy in improving the electronic and magnetic properties of the tapes and enhancing the capacity for carrying current at high magnetic fields. The limit of the bulk self-field-J c can be calculated by the relationships of J c vs. D. The limit is estimated to be on the order of 200 kA/cm2 for multifilamentary Bi-2223 tapes, which was supported by magneto-optical (MO) magnetization measurements results. It is a hard task to approach this limit with the present state of the art in manufacturing Ag/Bi-2223 tape, and it is the time to suggest some new ideals for Bi-2223 tapes to promote large-scale applications. 相似文献
4.
Zhongming Yan Haitao Li Hui Shao Rui Wu Yu Wang 《Journal of Superconductivity and Novel Magnetism》2012,25(6):1829-1832
This paper summarizes the experimental investigations on the critical current of two jointed Bi-2223/Ag superconducting tapes connected by Sn63Ag2Pb solder. Different lap lengths of contact surface were studied. The joint resistance was measured to be in the range of 0.059??0.76????, and the critical current of the jointed Bi-2223/Ag HTS tapes was measured with different charging rates using standard four-point-method in a zero-applied magnetic field applying 1 ??V/cm criterion. The experimental results showed that the longer the lap length was, the smaller the joint resistance was and the nearer the critical current approached that of Bi-2223/Ag superconducting short-sample. On the other hand, the critical current decreased with the increasing of the charging rate. 相似文献
5.
本文对国内某公司高温Bi-2223超导线材的典型宏观缺陷进行了观察,用EDS对缺陷成分进行了分析,并测试了缺陷处临界电流Ic值,结果表明,点缺陷和鼓泡两种典型缺陷都使Bi-2223超导线材缺陷处临界电流值出现了衰减,在点缺陷处Zr元素出现了偏析. 相似文献
6.
W. M. Chen W. Chen S. H. Zhou H. Y. Ling S. S. Jiang 《Journal of Superconductivity》2003,16(3):495-499
Multifilamentary Bi-2223 tapes were fabricated by PIT, using a silver alloy sheath with 2.5% magnesium metal. Outgrowth and bridging are major disadvantages for some silver alloy sheathed Bi-2223 tapes. To solve the outgrowth problem, green tapes were pressed with different reduction rates and then sintered at high temperatures. Critical current I
c of the sintered tapes was measured at nitrogen temperature using the four-probe method. The morphology of the filament core was observed with scanning electron microscope (SEM) to investigate outgrowth of sintered tapes with different reduction rates. Outgrowth and bridging on cross and longitudinal sections of filaments were studied using TEM images. Experimental results suggest that pressing processing may diminish outgrowth and bridging. Number of outgrowths and cases of bridging are reduced when the reduction rate increases, but the slope of the reduction falls at large reduction rates. The I
c curve indicates that there is an optimum reduction rate at which I
c reaches a maximum. At the best reduction rate the amount of outgrowth and bridging is close to the lowest. Experimental results show that pressing processing can diminish outgrowth and bridging by as much as 50%. Therefore, proper pressing is an effective method for both diminishing outgrowth and bridging and enhancement of I
c. 相似文献
7.
Berdan Özkurt 《Journal of Superconductivity and Novel Magnetism》2013,26(2):261-266
In this study the mechanical properties of Bi1.7?x Y x Pb0.3Sr2Ca2Cu3O y (x=0, 0.05, 0.1, and 0.25) samples with doped Yttrium are investigated. The load-independent Vickers hardness (H 0), Young’s modulus, and yield strength of samples are calculated. The possible reasons for the observed changes in mechanical properties are investigated by using different approaches such as the Hays–Kendall approach. These mechanical properties of the samples were found to be load and Yttrium content dependent. 相似文献
8.
To improve on present critical current (J
c) performance, multifilamentary Ag/Bi-2223 tapes with a large range of reduction rates were manufactured. The relative core mass density D was calculated, dependent on the measured geometric dimensions of the tapes. Experimental results, D vs. J
c, D vs. maximum pinning force density F
max
, and D vs. irreversible magnetic field B
irr, are quantitatively formatted. In particular, the magnetic field dependence of J
c is critically dependent on its core density. If the core density increases by 10%, J
c of the tapes in this experiment is enhanced by as much as 100%. Therefore, in the present state of the technological process for manufacturing Ag/Bi-2223 tape, increasing the core density is clearly a significant strategy in improving the electronic and magnetic properties of the tapes and enhancing the capacity for carrying current at high magnetic fields. The limit of the bulk self-field-J
c can be calculated by the relationships of J
c vs. D. The limit is estimated to be on the order of 200 kA/cm2 for multifilamentary Bi-2223 tapes, which was supported by magneto-optical (MO) magnetization measurements results. It is a hard task to approach this limit with the present state of the art in manufacturing Ag/Bi-2223 tape, and it is the time to suggest some new ideals for Bi-2223 tapes to promote large-scale applications. 相似文献
9.
10.
B. P. Mikhailov G. S. Burkhanov P. E. Kazin V. V. Lennikov S. V. Shavkin G. V. Laskova A. A. Titov 《Inorganic Materials》2001,37(11):1199-1200
The microstructure, phase composition, and superconducting properties of Bi-2223 ceramics doped with 0.05–0.5 wt % TaC were investigated. The materials were heat-treated at 840°C in three steps (10 + 24 + 24 h). By optimizing the TaC content and heat-treatment conditions, the 77-K critical current density of the Bi-2223 ceramics in zero field was raised by a factor of 2. 相似文献
11.
X. P. Chen X. W. Yu M. Y. Li H. B. Sun Q. Liu 《Journal of Superconductivity and Novel Magnetism》2013,26(2):333-336
The influence of green tape thickness on the Bi-2223 phase formation and texture evolution in Ag/Ni composite-sheathed tapes fabricated by the “powder-in-tube” technique has been studied. Microstructural observations by SEM as well as critical current density (J c) measurements at 77 K, 0 T have been performed to analyze the performance of the tapes. The results show an important influence of the green tape thickness on the critical current depending on the content and texture of Bi-2223 phase. The J c increases with decreasing thickness. Moreover, texture measured by omega scans shows that the texture of the Bi-2223 phase is significantly influenced by the thickness of the green tape after the first and final sintering processes. Alignment of Bi-2223 grains in the thin tapes is much better. Higher performance of Ag/Ni composite-sheathed Bi-2223 tapes can be obtained by controlling the thickness of the green tapes. 相似文献
12.
O. Bilgili Y. Selamet K. Kocabaş 《Journal of Superconductivity and Novel Magnetism》2008,21(8):439-449
The effects of Li substitution on the properties of high temperature superconductor Bi17Pb0.3Sr2C2Cu3−x
Li
x
O
y
were investigated. The samples were prepared by substituting Li (x=0.00–0.20) with changing ratios by a solid state reaction method. The samples were characterized by X-ray diffraction, DC
electrical resistivity, AC magnetic susceptibility, and scanning electronic microscopy (SEM). The X-ray diffraction studies
were done at room temperature and the lattice constants of the material were determined by indexing all the peaks observed.
This study shows that there are two coexisting phases; high-T
c
(2223) phase and low-T
c
(2212) phase. The lattice structure of the material belongs to the orthorhombic unit cell. The volume fraction was estimated
from the intensities of Bi-(2223) and Bi-(2212) phases. The sample with 20 wt% of added Li showed the higher volume fraction
of Bi-(2223) phase formed (81%) compared to the other samples. The DC electrical resistivity of all the samples decreased
as the wt% of Li increased. Both the onset critical temperatures T
c
(onset) and zero electrical resistivity critical temperatures T
c
(R=0) of the samples were determined from the DC electrical resistivity measurements. The observed value of the onset critical
T
c
(onset) temperature was 110 K agreeing well with the magnetic susceptibility measurements. We obtained T
c
onset at 112 K from AC magnetic susceptibility measurements.
相似文献
13.
W. M. Chen D. Q. Shi Y. C. Guo X. K. Fu H. K. Liu T. Silver S. X. Dou 《Journal of Superconductivity》2001,14(4):539-543
Three Ag sheathed Bi-2223 multifilamentary tapes were produced by a processing method that consists of two sintering treatments with an intermediate deformation, involving sandwich rolling (SR), pressing (P), or normal rolling (NR). The magnetic field dependence of the critical current density J
c was measured with the magnetic field H applied parallel to both the ab plane (H ab) and the c-axis (H c) of the Bi-2223 grains. Experimental results show that J
c of the pressed (P) tape (J
cP) for both H ab and H c is about 1.5–1.8 times higher than that for the NR tape (J
cNR) and the SR tape, although J
cSR is always larger than J
cP. The ratio of J
cSR/J
cNR for H c increases rapidly with the applied magnetic field and reaches a maximum of about 12 at 0
H 900 T. The calculated density of the pinning force F as a function of magnetic field shows that curves of F for SR, NR, and P tapes all have their maximum F
max at different magnetic fields and the magnitudes of F
max are also different from each other. The SR tape has the largest value of F
max, while NR has the smallest. XRD analysis shows that an intermediate deformation can destroy the grain alignment, and the larger the deformation, the worse the grain texture will be. Our experimental results, however, clearly show that J
c for Bi-2223 multifilamentary tapes is independent of grain alignment. The significant differences in J
c for tapes processed using the three different intermediate deformation procedures are dependent on the density of the pinning force and cannot be attributed to the grain alignment. Our experimental results support the view that SR processing is the best method for fabricating Ag/Bi-2223 tapes of high quality. 相似文献
14.
Kemal Kocabas Oya Özkan Ozlem Bilgili Yelda Kadıoglu Hatice Yılmaz 《Journal of Superconductivity and Novel Magnetism》2010,23(8):1485-1492
The effects of Mg substitution in Bi-2223 superconductor system has been studied for the Bi1.7Pb0.3Sr2Ca2Cu3−x
Mg
x
O
y
nominal composition (x=0.00, 0.05, 0.10, 0.15 and 0.20) which was prepared by the conventional solid-state reaction. The properties of these compounds
have been investigated by measuring the electrical resistivity, X-ray diffraction (XRD) and density. Also, scanning electron
microscopy (SEM) was employed to investigate the surface microstructure of the samples. It has been found that the effects
of Mg substitution support the development of both the Bi-2212 and Bi-2223 phases. These measurements and analyses enable
us to discuss the effects of Mg dopant on superconducting properties. We found that onset critical temperatures (T
c, onset) decrease with addition x>0.10 in resistivity measurements. The presence of Mg influenced the microstructure of the samples and decreased the mean
grain size of Bi-2223 grains up to x=0.10. 相似文献
15.
O. Ozturk E. Asikuzun S. Kaya M. Coskunyurek G. Yildirim M. Yilmazlar C. Terzioglu 《Journal of Superconductivity and Novel Magnetism》2012,25(7):2481-2487
This study includes two parts: (I)?investigation of the effect of different annealing time (10?h, 30?h, and 60?h) on physical, superconducting, and microstructural properties of Fe-diffused Bi-2223 superconductor ceramics prepared by the conventional solid-state reaction method with the aid of the X-ray diffraction (XRD), scanning electron microscopy (SEM), dc resistivity (???CT) and transport critical current density (J c ) measurements, and (II) determination of the diffusion coefficient and the activation energy of iron in the Bi-2223 system. In the former part, the zero-resistivity transition temperature (T c ), phase purity, volume fraction, hole-carrier concentration, lattice parameters, surface morphology, texturing, crystallinity, grain connectivity, grain size, and room temperature resistivity values of the bulk samples are found and compared with each other. The results obtained show that both the zero resistivity transition temperature (T c ) and transport critical current density (J c ) regularly enhance with the increment in the diffusion-annealing time. The maximum T c of 107±0.2 K and J c of 50.0?A?cm?2 are observed for the sample annealed at 830?°C for 60?h. As for the XRD investigations, according to the refinement of cell parameters done by considering the structural modulation, the enhancement in the diffusion-annealing is confirmed by both a decrease of the cell parameter a and an increase of the lattice parameter c of the samples, meaning that the greatest Bi-2223 phase fraction belongs to the sample annealed at 830?°C for 60?h. Moreover, SEM images display that the sample has the best crystallinity, grain connectivity, and largest grain size. Based on the results, the superconducting and microstructural properties improve with the increase in the diffusion-annealing time. In the latter part, Fe diffusion in the Bi-2223 system is examined in a range of 500?C830?°C by the variation of the lattice parameters evaluated from the XRD patterns. The temperature dependence of the Fe diffusion coefficient is described by the Arrhenius relation D=4.27×10?5exp(?1.27±0.10) eV/kBT, and the related activation energy of the iron in the Bi-2223 system is found to be about 1.27?eV. The relatively low value of activation energy obtained illustrates that the migration of the Fe ions primarily proceeds through defects such as pore surfaces and grain boundaries in the polycrystalline structure, leading to the improvement of the microstructural and superconducting properties of the samples, supported by the results of part?I. All in all, the aim of the present study is not only to analyze the role of diffusion-annealing time on superconducting and microstructural properties of Fe-diffused Bi-2223 superconductors, but also to find the diffusion coefficient and activation energy of Fe in the Bi-2223 system. 相似文献
16.
E. M. M. Ibrahim S. A. Saleh S. A. Ahmed 《Journal of Superconductivity and Novel Magnetism》2008,21(4):217-221
Structural examination and thermoelectric power measurement are made on Bi1.75Pb0.35Sr2Ca2Cu3O10 samples sintered at different conditions. Thermoelectric power of all samples was found to be positive and it increases almost
linearly with the decrease of temperature up to ∼140 K, before falling to zero at T
co. However, the thermoelectric power changes slightly with increasing sintering temperature and time. The normal state results
are analyzed in terms of a two-band model with an additional linear part T. The effects of sintering temperature and time on the parameters related to this model have been investigated.
An erratum to this article can be found at 相似文献
17.
Kemal Kocabaş Melis Gökçe Muhsin Çiftçioğlu Özlem Bilgili 《Journal of Superconductivity and Novel Magnetism》2010,23(3):397-410
In this work, effects of compaction pressure on the structural and superconducting properties of BSCCO ceramic superconductors
were investigated. The study was carried out on two systems which were, System I: Bi1.7Pb0.3Sr2Ca2Cu3O
y
and System II: Bi1.6Pb0.3Ag0.1Sr2Ca2Cu3O
y
, respectively. Ceramic powders were prepared by conventional solid-state reaction method and sintered at 850°C after compaction
at five different pressures in the 150–750 MPa range. Critical temperatures of samples were determined by resistivity-temperature
determinations made by four-point probe method in liquid nitrogen conditions. XRD analysis was conducted by powder X-ray diffraction
method. Morphology of the grains present in the samples were determined by using scanning electron microscope (SEM) photographs
at 2 K× and 2.5 K× magnifications for System I and System II, respectively. Sintered densities of the superconducting ceramics
were measured by Archimedes water displacement method and unit cell parameters were additionally obtained from XRD data. T
c values for System I was determined to be in the 109–115 K with sample D having the highest T
c of 115 K while T
c varied in the 104–109 K range and sample B had the highest T
c value of 109 K for System II. The transition width, which is a sign of the purity of the samples, was determined to be narrow
for both systems. The data obtained from X-ray diffraction measurements have shown that 2223 high-T
c phase was dominant in both systems. The determination of the optimum pellet compaction pressure for BSCCO ceramic superconductors
was the main purpose of this work. The results of this work indicated that compaction at around 450 MPa improves the superconducting
and structural properties of the BSCCO ceramic superconductors. 相似文献
18.
19.
用形变热处理工艺制备了Bi2223/Ag-Au带材,通过X射线衍射仪、超导量子干涉仪及标准四引线法研究了第1次热处理温度对带材中的相成分及载流能力的影响.结果显示:热处理温度超过840℃时,带材中会出现Bi2201相;热处理温度太低时不仅带材成相速率慢,而且带材中会出现较多的第二相.第1次热处理后,Bi2223相的转化率应该控制在85%附近,Pb离子进入到Bi2212晶格内,带材中有最少的Bi2201相、最少的其它非超导第二相有利于带材最终性能的提高. 相似文献
20.
Nihal Türk Hakan Gündoğmuş Mustafa Akyol Z. Deniz Yakıncı Ahmet Ekicibil Bekir Özçelik 《Journal of Superconductivity and Novel Magnetism》2014,27(3):711-716
The superconducting Bi1.6Pb0.4Sr2Ca2Cu3?x W x O10+y (x=0.00, 0.05, 0.10, 0.15) bulk samples were prepared by the solid-state reaction method. The effects of W substitution on the BSCCO system have been investigated by the electrical resistivity (ρ-T), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), magnetic hysteresis and critical current density measurements. It has been found that the Bi-(2212) low-T C phase is formed for all the substitution levels, together with the Bi-(2223) high-T C phase. The results obtained from the XRD data show that the Bi-(2223) phase gradually transforms into the Bi-(2212) phase with increasing W substituting for Cu. In addition, from the magnetization measurements at the temperatures below the zero resistance temperatures of the samples, we have observed that a decreasing in magnitude of |M| with the increasing measurement temperature and W concentration. Therefore, the decreasing of |M| related to superconducting volume seems to imply an existence of flux-pinning centers in our samples. 相似文献