Enhancement in critical current density and irreversibility field of bulk MgB<sub>2</sub>by C and CaCO<sub>3</sub>co-addition

Tan, K.S.; Chen, Soo Kien; Jun, Byung‐Hyuk; Kim, C. J.

doi:10.1088/0953-2048/21/10/105013

Cited by 14 publications

(8 citation statements)

References 21 publications

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“…Therefore, it is necessary to study the doping effect of suitable elements in MgB 2 . Out of several dopants, carbon C [97] and carbon containing compounds, such as SiC [98], C and CaCO 3 co-addition [99] have been reported to be effective for improving the flux pinning properties of MgB 2 . Employing HPCVD technique, so far carbon has been doped in MgB 2 films, using (MeCp) 2 Mg [100] and methane [101] as the carbon source.…”

Section: Flux Pinning and Sic Dopingmentioning

confidence: 99%

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Ranot

Kang

2012

Current Applied Physics

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The MgB 2 coated superconducting tapes have been fabricated on textured Cu (0 0 1) and polycrystalline Hastelloy tapes using coated conductor technique, which has been developed for the second generation high temperature superconducting wires. The MgB 2 /Cu tapes were fabricated over a wide temperature range of 460-520 °C by using hybrid physical-chemical vapor deposition (HPCVD) technique. The tapes exhibited the critical temperatures (T c ) ranging between 36 and 38 K with superconducting transition width (∆T c ) of about 0.3-0.6 K. The highest critical current density (J c ) of 1.34 × 10 5 A/cm 2 at 5 K under 3 T is obtained for the MgB 2 /Cu tape grown at 460 ºC. To further improve the flux pinning property of MgB 2 tapes, SiC is coated as an impurity layer on the Cu tape. In contrast to pure MgB 2 /Cu tapes, the MgB 2 on SiC-coated Cu tapes exhibited opposite trend in the dependence of J c with growth temperature. The improved flux pinning by the additional defects created by SiC-impurity layer along with the MgB 2 grain boundaries lead to strong improvement in J c for the MgB 2 /SiC/Cu tapes. The MgB 2 /Hastelloy superconducting tapes fabricated at a temperature of 520 °C showed the critical temperatures ranging between 38.5 and 39.6 K. We obtained much higher J c values over the wide field range for MgB 2 /Hastelloy tapes than the previously reported data on other metallic substrates, such as Cu, SS, and Nb. The J c values of J c (20 K, 0 T) ~5.8 × 10 6 A/cm 2 and J c (20 K, 1.5 T) ~2.4 × 10 5 A/cm 2 is obtained for the 2-µm-thick MgB 2 /Hastelloy tape. This paper will review the merits of coated conductor approach along with the HPCVD technique to fabricate MgB 2 conductors with high T c and J c values which are useful for large scale applications.

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Section: Flux Pinning and Sic Dopingmentioning

confidence: 99%

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Ranot

Kang

2012

Current Applied Physics

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“…Along with the physical method, the J c of MgB 2 can be increased by the doping of chemical species such as silicon carbide [23], carbon-related materials [24], and other fine impurity phases [25]. The carbon doping to MgB 2 not only led to the formation of a lattice strain [26], and lattice substitution [26][27][28][29][30][31] but also increased the number of grain boundaries [32]. Mechanical milling for boron powder is an alternative way to increase the J c of MgB 2 through the grain size refinement of MgB 2 [32].…”

Section: Introductionmentioning

confidence: 99%

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

S.H.Kim¹,

Kang²,

Jun³

et al. 2017

Progress in Superconductivity and Cryogenics

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The effects of MgB 4 addition on the superconducting properties and the microstructure of in situ processed MgB 2 bulk superconductors were studied. MgB 4 powder of 1-20 wt.% was mixed with (Mg + 2B) powder and then pressed into pellets. The pellets of (Mg + 2B + xMgB 4 ) were heat-treated at 650 ℃ for 1 h in flowing argon. The powder X-ray diffraction (XRD) analysis for the heat-treated samples showed that the major formed phase in all samples was MgB 2 and the minor phases were MgB 4 and MgO. The full width at half maximum (FWHM) values showed that the grain size of MgB 2 decreased as the amount of MgB 4 addition increased. MgB 4 particles included in a MgB 2 matrix is considered to suppress the grain growth of MgB 2 . The onset temperatures (T c,onset ) of MgB 2 with MgB 4 addition (0-10 wt.%) was between 37-38 K. The 20 wt.% MgB 4 addition slightly reduced the T c,onset of MgB 2 to 36.5 K. This result indicates that MgB 4 addition did not influence the superconducting transition temperature (T c ) of MgB 2 significantly. On the other hand, the small additions of 1-5 wt.% MgB 4 increased the critical current density (J c ) of MgB 2 . The J c enhancement by MgB 4 addition is attributed not only to the grain size refinement but also to the possible flux pinning of MgB 4 particles dispersed in a MgB 2 matrix.

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“…Besides, the lower cost of the starting materials of magnesium (Mg) and boron (B) powders compared to Nb-Ti or Nb 3 Sn is also an additional benefit for practical applications. Many attempts have been conducted to fabricate this material with the aim of improving its superconducting properties under high magnetic fields through a doping with various forms of carbon (C) such as SiC, C compounds, carbohydrate and hydrocarbon [1][2][3][4][5][6][7][8][9]. However, processing pure MgB 2 samples with good quality is equally important and costeffective without the use of dopants.…”

Section: Introductionmentioning

confidence: 99%

Enhanced critical current properties of in situ processed MgB2 wires using milled boron powder and low temperature solid-state reaction

Jun

Kim

Tan

et al. 2010

Journal of Alloys and Compounds

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Enhancement in critical current density and irreversibility field of bulk MgB₂by C and CaCO₃co-addition

Cited by 14 publications

References 21 publications

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

Enhanced critical current properties of in situ processed MgB2 wires using milled boron powder and low temperature solid-state reaction

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Enhancement in critical current density and irreversibility field of bulk MgB2by C and CaCO3co-addition

Cited by 14 publications

References 21 publications

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Enhanced critical current density of in situ processed MgB2 bulk superconductors with MgB4 additions

Enhanced critical current properties of in situ processed MgB2 wires using milled boron powder and low temperature solid-state reaction

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Enhancement in critical current density and irreversibility field of bulk MgB₂by C and CaCO₃co-addition

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions