Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

Lin, He; Yao, Chao; Zhang, Xianping; Zhang, Haitao; Wang, Dongliang; Zhang, Qianjun; Ma, Yanwei; Awaji, Satoshi; Watanabe, Kazuo

doi:10.1038/srep04465

Cited by 45 publications

(74 citation statements)

References 32 publications

(64 reference statements)

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“…Example of FeSe0.5Te0.5-coated conductors have been already reported. 43 Thin films growth by PLD with a CeO2 buffer, on coated conductor substrates exhibit critical current densities >10 6 …”

Section: Discussionmentioning

confidence: 99%

“…Indeed, the best transport critical current density, Jc, up to 10 5 -10 6 A/cm 2 in self field, has been obtained so far with the 122 family. 5,6 Recently, Jc values above the practical level (10 5 A/cm 2 at 10 T) have been Indeed, they suffer the loss of fluorine as a consequence of both the thermal treatment 9 and the strong interdiffusion with the metal sheaths. 10 Recently, a transport critical current density above 10 4 A/cm 2 at 4.2 K and in self-field has been achieved in 1111 tapes, but it is strongly suppressed by the field.…”

Section: Introductionmentioning

confidence: 99%

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Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

Palombo

Malagoli

Pani

et al. 2015

Journal of Applied Physics

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In this work, the feasibility condition of Powder-In-Tube (PIT) processed wires of Fe(Se,Te) superconductor has been investigated. We faced several technical issues that are extensively described and discussed. In particular, we tested different metals and alloys as external sheaths (Cu, Ag, Nb, Ta, Ni, Fe, cupronickel, brass) concluding that the only sheath that does not affect substantially the Fe(Se,Te) phase is Fe. On the other hand, Fe sheath introduces excess iron in the Fe(Se,Te) phase, which affects the superconducting properties; we investigated the effects of the thermal treatments and of the powder composition in order to avoid it. The maximum Jc value obtained in our samples is 4•10 2 A/cm 2 , comparable to other published values of PIT conductors of the 11 family. We conclude that the fabrication of Fe(Se,Te) wires by PIT method is quite challenging and other approaches should be developed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

Palombo

Malagoli

Pani

et al. 2015

Journal of Applied Physics

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“…For the flat-rolling method, which can be used to produce a long wire/tape for a practical application, it is still difficult to fabricate wires/tapes with high J c values [15], [16]. At the same time, it should be noted that the rapid J c improvement was only obtained in Ag-sheathed 122 samples [12]- [16], whereas the J c of the Fe-sheathed samples, which have a relatively low production cost, is still kept in low values [11], [17].…”

mentioning

confidence: 95%

Investigation of <inline-formula> <tex-math notation="TeX">$J_{c}$</tex-math></inline-formula>-Suppressing Factors in Flat-Rolled <inline-formula> <tex-math notation="TeX">$\hbox{Sr}_{0.6}\hbox{K}_{0.4}\hbox{Fe}_{2}\hbox{As}_{2}/\hbox{Fe}$</tex-math></inline-formula> Tapes Via Microstructure Analysis

Zhang¹,

Wang

et al. 2015

IEEE Trans. Appl. Supercond.

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Pnictide superconductors will be very promising for applications if wires with high critical current density J c can allow reel-to-reel large-scale fabrication at low costs. To understand the mechanism(s) that limited J c in flat-rolled Sr 0.6 K 0.4 Fe 2 As 2 (Sr122) tapes, microstructure analysis has been considered the most direct and efficient way. Here, we report on high-resolution microstructure imaging and analysis on Fe-sheathed flat-rolled Sr122 tapes, which have a J c as high as 2.3 × 10 4 A/cm 2 at 10 T and 4.2 K. The overlapping nature of the Sr122 plates was clearly observed. Transmission electron microscopy/scanning transmission electron microscopy analysis showed that, besides the cracks formed during the fabrication process, the SrO 2 phase and cavities caused by the inhomogeneously dispersed Sr and K are the other important factors suppressing J c . The wetting phase FeAs at the grain boundaries can be partially substituted by Sn in Sn-added samples. Our findings provide insights that pave the way to further enhance the critical current of the rolled 122 tapes up to the practical level.

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“…Among these proposed processes, the powder-in-tube (PIT) method seems the most promising technique for practical applications [19][20][21]. Thus, the Ba(Sr)122 PIT wires have been investigated intensively [22][23][24][25][26][27][28][29][30][31], and high J c exceeding the level of 10 4 A/cm 2 at 4.2 K and 10 T has been reported for short samples prepared by applying uniaxial pressing [32][33][34][35].…”

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confidence: 99%

High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

Gao

Togano

Matsumoto

et al. 2014

Supercond. Sci. Technol.

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Abstract:The recently discovered iron-based superconductors with very high upper critical field (H c2 ) and small anisotropy have been regarded as a potential candidate material for high field applications. However, enhancements of superconducting properties are still needed to boost the successful use of iron-based superconductors in such applications. Here, we propose a new sheath architecture of stainless steel (SS)/Ag double sheath and investigate its influence on the microstructures and J c -H property.We found that the transport J c -H curves for rolled and pressed tapes both show extremely small magnetic field dependence and exceed 3×10 4 A/cm 2 under 28 T, which are much higher than those of low-temperature superconductors. More interestingly, 12 cm long rolled tape shows very high homogeneity and sustains J c as high as 7.7×10 4 A/cm 2 at 10 T. These are the highest values reported so far for iron-based superconducting wires fabricated by scalable rolling process. The microstructure investigations indicate that such high J c was achieved by higher density of the core and uniform deformation resulting better texturing. These results indicate that our process is very promising for fabricating long Ba122 wires for high field magnet, i.e. above 20 T.* Author to whom correspondence should be addressed; E-mail: KUMAKURA.Hiroaki@nims.go.jp 2The recently discovered iron-based superconductors have attracted great interest as a subject of both fundamental study and practical applications [1][2][3][4][5][6][7][8][9]. Among the various iron based superconductors, 122-type (AE)Fe 2 As 2 (AE = Sr, Ba) is very attractive for high field applications due to its excellent properties such as very high upper critical field (H c2 ), relatively small anisotropy [10,11], and an advantageous grain-boundary nature [12]. In order to achieve high critical current density (J c ) various processing techniques have been used [13][14][15][16][17][18]. Among these proposed processes, the powder-in-tube (PIT) method seems the most promising technique for practical applications [19][20][21]. Thus, the Ba(Sr)122 PIT wires have been investigated intensively [22][23][24][25][26][27][28][29][30][31], and high J c exceeding the level of 10 4 A/cm 2 at 4.2 K and 10 T has been reported for short samples prepared by applying uniaxial pressing [32][33][34][35].However, unfortunately, pressing processes are usually applicable only for a short sample and it is difficult to attain such high J c values with good reproducibility. For practical applications, it is desirable if high J c values are attained with good reproducibility by rolling, which is easy to scale up to the long length wire production.Although silver looks the most suitable sheath material for 122 phase, there are a number of drawbacks of using pure Ag as the sheathing material: poor mechanical properties after the heat treatment that make the coil winding difficult and limit its ability to support Lorentz forces in high magnetic fields, and high occurrence of sausaging during mechan...

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Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

Cited by 45 publications

References 32 publications

Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

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Strongly enhanced current densities in Sr0.6K0.4Fe2As2 + Sn superconducting tapes

Cited by 45 publications

References 32 publications

Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

Exploring the feasibility of Fe(Se,Te) conductors by ex-situ powder-in-tube method

High transportJcin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

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High transportJ_cin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process