Zn doping of YBa2Cu3O7 in melt textured materials: peak effect and high trapped fields

Krabbes, G.; Fuchs, G.; Schätzle, P.; Gruss, S.; Park, J.W; Hardinghaus, Ferdinand; Stöver, G.; Hayn, R.; Drechsler, S.‐L.; Fahr, T.

doi:10.1016/s0921-4534(99)00616-4

Cited by 133 publications

(75 citation statements)

References 34 publications

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“…[4,5] Cracking of the samples was found to limit the trapped field of bulk YBCO at temperatures below 77 K which can be explained by tensile stresses that occur during the magnetization process due to the stored flux density gradient and may exceed the tensile strength of the material.…”

Section: Ge 7462bf 7480bjmentioning

confidence: 99%

“…[1] The pinning effect in melt textured samples can be improved by irradiation methods [2,3] and alternatively, by zinc-doping. [4,5] Cracking of the samples was found to limit the trapped field of bulk YBCO at temperatures below 77 K which can be explained by tensile stresses that occur during the magnetization process due to the stored flux density gradient and may exceed the tensile strength of the material. [6] The mechanical properties of bulk YBCO and its tensile strength can be improved considerably by the addition of Ag.…”

mentioning

confidence: 99%

“…Details of the sample preparation are reported elsewhere. [4,11,12] The applied melt process results in large-domain monoliths up to 50 mm in diameter and about 12 mm in height. The a, b-planes of the large grains were oriented parallel to the surface of the cylindrically shaped samples.…”

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confidence: 99%

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Superconducting bulk magnets: Very high trapped fields and cracking

Gruss

Fuchs

Krabbes

et al. 2001

Applied Physics Letters

160

109

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Improved trapped fields are reported for bulk melt-textured YBa2Cu3O 7−δ (YBCO) material in the temperature range between 20 K and 50 K. Trapped fields up to 12.2 T were obtained at 22 K on the surface of single YBCO disks (with Ag and Zn additions). In YBCO mini-magnets, maximum trapped fields of 16 T (at 24 K) and of 11.2 T (at 47 K) were achieved using (Zn + Ag) and Zn additions, respectively. In all cases, the YBCO disks were encapsulated in steel tubes in order to reinforce the material against the large tensile stress acting during the magnetizing process and to avoid cracking. We observed cracking not only during the magnetizing process, but also as a consequence of flux jumps due to thermomagnetic instabilities in the temperature range betweeen 20 K and 30 K. 7460Ge, 7462Bf, 7480BjBulk type II superconductors can trap high magnetic fields that are generated by superconducting persistent currents circulating macroscopically within the superconductor. The main features of the resulting field distribution are a maximum trapped field B 0 in the center of the superconducting domain and a field gradient towards the sample edge which is determined by the critical current density j c of the supercurrents. Therefore, high trapped fields B 0 in bulk superconductors require a high critical current density and a large size of the current loops. Large single-domain bulk YBa 2 Cu 3 O 7−δ based (YBCO) samples can be produced by melt texture processing, especially by using SmBa 2 Cu 3 O 7−δ (Sm-123) as a seed crystal.[1] The pinning effect in melt textured samples can be improved by irradiation methods [2,3] and alternatively, by zinc-doping. [4,5] Cracking of the samples was found to limit the trapped field of bulk YBCO at temperatures below 77 K which can be explained by tensile stresses that occur during the magnetization process due to the stored flux density gradient and may exceed the tensile strength of the material.[6] The mechanical properties of bulk YBCO and its tensile strength can be improved considerably by the addition of Ag. [7,8] Another possibility to avoid cracking during magnetizing is to encapsulate the bulk YBCO disks in steel tubes. [9] A steel tube leads to stress compensation by generating a compressive stress on YBCO after cooling from 300 K to the measuring temperature which is due to the higher thermal expansion coefficient of steel compared to that of YBCO in the a, b-plane. Maximum trapped fields B 0 of 11.5 T at 17 K and of 14.4 T at 22 K were reported for single YBCO disks and mini-magnets consisting of two single YBCO disks, respectively. [9] In both cases, Ag was added to the YBCO disks which were placed into austenite Cr-Ni steel tubes. Previous attempts to combine the two beneficial effects of Ag and Zn additions failed due to the solubility of Zn in Ag in oxygen atmosphere. High trapped fields have also been reported for bulk Sm-123 with additions of Ag. At the surface of Sm-123 disks, trapped fields of 2.1 T at 77 K and of 8 T at 40 K have been observed. [10] In the present paper, t...

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Section: Ge 7462bf 7480bjmentioning

confidence: 99%

mentioning

confidence: 99%

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Superconducting bulk magnets: Very high trapped fields and cracking

Gruss

Fuchs

Krabbes

et al. 2001

Applied Physics Letters

160

109

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“…The phases obtained for YBCO by the preparation technique used here are Y 2 BaCuO 5 , CuO and BaCuO 2 [26], whereas for La1113 are CaO, Ca 2 CuO 3 , CuO and BaCuO 2 [11]. The presence of secondary phases is a possible explanation for the origin of the fishtail or peak effect [28,29] as we will discuss below. Moreover, for both cases the magnetization |M| decreases as the external field goes from H C1 to H C2 .…”

Section: Resultsmentioning

confidence: 84%

Magnetic Properties of the Superconductor LaCaBaCu3O7~!2010-02-11~!2010-04-01~!2010-06-29~!

V.¹,

D.²,

González³

et al. 2010

TOSUPERJ

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LaCaBaCu 3 O 7 (La1113) is a superconductor below T C(onset) =80K and its structure is similar to the tetragonal YBCO. In this work the magnetic properties of a bulk La1113 sample are reported and compared to those of YBCO superconductor. We explore a possibly relation of this property to its particular crystalline structure, particularly to the oxygen deficiency. In contrast to a bulk YBCO, some magnetic characteristics of La1113 below T C are: the magnetic flux can penetrate easily the bulk in its vortex region (H C1

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“…It could mean that Ti actually did not occupy the Y-sites but the Cu-ones. On the other hand, a low Zn substitution for Cu in the Y-123 system (Krabbes et al, 2000) or Fe, Co, or Ni substitutions for Cu in Bi-2212 single crystals were found to enhance J c (Shigemori et al, 2004). These results showed that a direct doping in superconducting CuO 2 planes is an effective method for introducing point-like pinning sites in cuprate Fig.…”

Section: Flux Pinning In Neg-123 Due To Tio 2 Nanoparticlesmentioning

confidence: 92%