Fabrication of high performance light rare earth based single-grain superconductors in air

Babu, N. Hari; Iida, K.; Shi, Yongjiang; Cardwell, D. A.

doi:10.1063/1.2131200

Cited by 45 publications

(33 citation statements)

References 18 publications

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“…Low field J 's have been measured to be kA/cm at 77 K and are comparable to those of Gd-123/Gd-211 composites fabricated from precursor pellets containing solid state reacted Gd-123 and Gd-211 powders. The maximum irreversibility field for Gd-123/Gd-211 composite is reported to be 5.5 T at 77 K [15]. This value increases to up to 6.5 T for Gd-123/Gd-2411 composite suggesting that the nano-scale RE-2411 inclusions pin magnetic flux, even under high external magnetic fields.…”

Section: Resultsmentioning

confidence: 70%

“…In this study we have enriched the BaO content of the precursor powder to achieve this effect. The optimum amount of BaO enrichment required for suppressing solid solution formation has been investigated in detail for various REBCO systems, independently of RE-2411 content [14], [15]. In order to study the influence of the addition of RE-2411 on the spatial variation of the superconducting properties of the single grains, several small samples were cut from the parent bulk grain and their T measured as a function of distance from the seed crystal.…”

Section: Resultsmentioning

confidence: 99%

“…A small quantity of Pt powder (0.05-0.1 wt%) was added to the precursor powders prior to pressing in order to suppress Ba-Cu-O liquid phase loss that occurs during melt processing. The precursor pellets for RE Gd and Sm were enriched with 1 wt% and 2 wt% BaO , respectively, in order to suppress solid solution formation during the melt growth process under an air atmosphere [14], [15]. Single grain superconductors with the above starting compositions were melt processed under air by the TSMG technique [13] using the heating profile described in [4].…”

Section: Methodsmentioning

confidence: 99%

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Bulk Superconducting Nano-Composites With High Critical Currents

Babu

Iida

Briffa

et al. 2007

IEEE Trans. Appl. Supercond.

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Abstract-Flux pinning sites are most effective if their size is comparable to the superconducting coherence length, which is on the nano-meter scale for RE-Ba-Cu-O superconductors [RE = rare earth element]. Introducing nano-phase inclusions directly into the bulk superconducting material has only been partially successful to date, however, due primarily to the absence of chemically stable phases that can co-exist with RE-Ba-Cu-O without suppressing its key superconducting properties. We have identified novel isostructural phases based on (RE) 2 Ba 4 CuMO y (where M = W, Zr, Nb, Ag and Bi) and have fabricated successfully superconducting bulk nano-composites with a high current carrying capability. The average size of the nano-inclusions is observed to vary from 20 nm to 300 nm depending on element M. An observed improvement in J c under low and high external magnetic fields at 77 K correlates directly with an increased density of nano-inclusions in the superconducting matrix.

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Bulk Superconducting Nano-Composites With High Critical Currents

Babu

Iida

Briffa

et al. 2007

IEEE Trans. Appl. Supercond.

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“…The precursor pellets for RE = Gd and Sm were enriched with 1 wt% and 2 wt% BaO 2 , respectively, in order to suppress solid solution formation during the melt growth process under an air atmosphere [21,22]. Single grain superconductors with the above starting compositions were melt processed under air via TSMG [20] using the heating profile described in [22]. A Mg-doped Nd-Ba-Cu-O generic seed crystal was used for the growth of GdBCO and SmBCO single grains, as reported in ref.…”

Section: Introductionmentioning

confidence: 99%

“…A small quantity of Pt powder (0.05-1 wt%) was added to the precursor powders prior to pressing in order to suppress Ba-Cu-O liquid phase loss that occurs during melt processing. The precursor pellets for RE = Gd and Sm were enriched with 1 wt% and 2 wt% BaO 2 , respectively, in order to suppress solid solution formation during the melt growth process under an air atmosphere [21,22]. Single grain superconductors with the above starting compositions were melt processed under air via TSMG [20] using the heating profile described in [22].…”

Section: Introductionmentioning

confidence: 99%

Enhanced magnetic flux pinning in nano-composite (re)-ba-cu-o bulk superconductors

Cardwell¹,

Babu²,

Iida³

2006

Nanopages

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Abstract. Nano-composite (RE)-Ba-Cu-O bulk superconductors containing non-superconducting phase inclusions of composition RE 2 Ba 4 CuMO y (the '2411' phase), where M = W, Nb, Ag and Bi, embedded in the REBa 2 Cu 3 O 7-δ (RE-123) superconducting matrix have been fabricated successfully. The 2411-phase has typical dimensions in the range 10-300 nm and is stable under the substitution of any rare earth element on the Y site for all M elements. The 2411-phase is paramagnetic in nature and is characterized by a double perovskite cubic crystallographic structure. All phases within the (RE)-2411 family are chemically inert within the RE-123 matrix and do not coarsen appreciably at elevated temperatures during processing. Most significantly, the (RE)-2411 phase forms effective flux pinning sites within the superconducting matrix, since their size is comparable to that of the coherence length of RE-Ba-Cu-O. A direct correlation between the RE 2 Ba 4 CuMO y phase inclusions content in the RE-123 matrix and increased magnetic flux pinning has been observed. The flux pinning force and the current densities increase by an order of magnitude for the nano-composites compared to that of bulk, melt processed RE-Ba-Cu-O without inclusions, confirming their potential for improved current carrying performance when processed in the form of bulk, thin-film or coated conductors.

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Growth of single‐grain GdBa₂Cu₃O_7‐x superconductors by top seeded infiltration and growth technique

Yang²,

Tang

et al. 2010

Cryst. Res. Technol.

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The top seeded infiltration and growth technique (TSIG) is an effective way for the preparation of bulk REBa2Cu3O7‐x (RE‐123, where RE denotes rare earth) with finely dispersed RE2BaCuO5 (RE‐211) particles compared to the conventional melt growth (MG) method. The nucleation temperature and the ending growth temperature are the most important parameters need to be optimized during the preparation of RE‐123 bulks by the TSIG process. In this paper, the effects of these parameters on the growth of single‐grain GdBa2Cu3O7‐x (GdBCO) superconductors have been investigated experimentally. It is found that the temperature for the growth of single‐grain GdBCO is in the region between 1040 °C and 1015 °C. In addition, the relation between growth rate and supercooling has been investigated in detail. The combined techniques of SEM and EDS were used to study the microstructure of the samples grown at different temperatures. Based on this, a two‐step slow cooling method during the crystallization process is proposed for the fabrication of RE‐123 bulks. Finally, the single‐grain GdBCO samples of the diameters 20 mm and 30 mm were fabricated successfully by the TSIG technique, with the slow‐cooling process in the temperature window 1030 °C–1020 °C for 60 h and 100 h respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Fabrication of high performance light rare earth based single-grain superconductors in air

Abstract: Articles you may be interested inHigh critical current density and its field dependence in mixed rare earth (Nd,Eu,Gd)Ba 2 Cu 3 O 7−δ thin films

Cited by 45 publications

References 18 publications

Bulk Superconducting Nano-Composites With High Critical Currents

Bulk Superconducting Nano-Composites With High Critical Currents

Enhanced magnetic flux pinning in nano-composite (re)-ba-cu-o bulk superconductors

Growth of single‐grain GdBa₂Cu₃O_7‐x superconductors by top seeded infiltration and growth technique

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Fabrication of high performance light rare earth based single-grain superconductors in air

Abstract: Articles you may be interested inHigh critical current density and its field dependence in mixed rare earth (Nd,Eu,Gd)Ba 2 Cu 3 O 7−δ thin films

Cited by 45 publications

References 18 publications

Bulk Superconducting Nano-Composites With High Critical Currents

Bulk Superconducting Nano-Composites With High Critical Currents

Enhanced magnetic flux pinning in nano-composite (re)-ba-cu-o bulk superconductors

Growth of single‐grain GdBa2Cu3O7‐x superconductors by top seeded infiltration and growth technique

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Growth of single‐grain GdBa₂Cu₃O_7‐x superconductors by top seeded infiltration and growth technique