Effects influencing the grain connectivity in ex-situ MgB2 wires

Kòváč, Pavol; Hušek, I; Kulich, M; Melíšek, T; Hušeková, K.; Dobročka, Edmund

doi:10.1016/j.physc.2010.01.067

Cited by 9 publications

(2 citation statements)

References 18 publications

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“…Hasil ini membuktikan bahwa penurunan ukuran partikel serbuk berkontribusi pada penguatan pembentukan fasa superkonduktor dalam bahan. Jika dibandingkan riset sebelumnya [12,[13][14][15] pencapaian transformasi fasa superkonduktor ini lebih tinggi dan tanpa terdeteksi fasa oksida Gambar 1. Pola XRD dari sampel sampel MGB400.…”

Section: Analisis Pembentukan Fasa Dan Ukuran Kristalitunclassified

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Herbirowo,

Yuwono,

Utomo

et al. 2023

JRM

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Studying the evolution of the MgB2 superconductor manufacturing process to improve critical temperature is important. The solid-state approach was used in this work to create a low-cost MgB2 superconductor. Variations in the purity of Boron were used as control parameters to evaluate the impact of dry milling on the production of the MgB2 bulk and low-temperature electrical properties. A 2:1 stoichiometric ratio of magnesium and boron powder was weighed and ground for 30 minutes. The ground powder was compressed and sintered for one hour at 1073 K. We were able to confirm through XRD and SEM research that the small particle size improved the MgB2 phase fraction and increase crystallite size in the production of the MgB2 sample. At 1073 K and 200 um of Mg, the sample sintered produced an MgB2 phase of 99.3%. The critical onset temperature (Tc-offset) improved from 39 to 40K, respectively.

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Section: Analisis Pembentukan Fasa Dan Ukuran Kristalitunclassified

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Herbirowo,

Yuwono,

Utomo

et al. 2023

JRM

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“…Kovac et al found that long time ageing (longer than three months) of ex situ MgB 2 wires before heat treatment dramatically affects the electrical properties, as a consequence of the absorption of O 2 , CO 2 and H 2 O from the surrounding air [28]. The values of T c , resistivity and connectivity A F , but also the transport properties (compare AE-5yrs and AE-std in section 3.2 and table 3), were also affected by ageing in the present case (the wire AE-5yrs).…”

Section: Critical Temperature Resistivity and Connectivitymentioning

confidence: 99%

Effect of cold high pressure deformation on the properties ofex situMgB₂wires

Kulich

Flükiger

Senatore

et al. 2013

Supercond. Sci. Technol.

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A substantially different behaviour was observed between MgB 2 wires produced either by in situ or ex situ processing after applying the recently developed technique of cold high pressure densification (or CHPD). In contrast to in situ wires, where densification at 1.5 GPa on binary and ternary alloyed in situ MgB 2 wires causes an enhancement of mass density and a strong enhancement of J c , ex situ wires up to 2 GPa show only a negligible enhancement of the MgB 2 mass density, while a considerable enhancement of J c is still observed. In both cases, this reflects an enhancement of grain connectivity, however in ex situ wires, the enhancement of J c is connected to the partial disruption of the oxide layer around each MgB 2 powder particle, in contrast to the enhancement of J c in situ wires, which is correlated to a smaller void fraction and a larger contact area between neighbouring grains.It is well known that J c of ex situ wires decreases after longer exposition times when exposed to air prior to annealing; after several months J c falls to values ≤50% of the original value. After cold pressing, we have found that J c of the same wire exceeded the original values, even after exposing the unreacted wire for >1 year to air. A lower electrical resistivity is measured on pressed ex situ MgB 2 wires, which confirms the improvement of grain connectivity due to the breakage of the oxide layers. Thus, the application of high pressure at room temperature allows us to recover the values of J c for ex situ wires even after they have been degraded either by low quality MgB 2 precursors or by prolonged ageing of the already formed wire prior to the final heat treatment. The limits of the J c enhancement in ex situ wires are discussed.

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Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology

Yücel

Belenli

2012

J Mater Sci: Mater Electron

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We have optimized fabrication conditions of MgB 2 /Fe superconducting monofilament tapes fabricated using ex-situ powder-in-tube method without any intermediate annealing. Influences of three effective parameters (annealing temperature, annealing time and argon (Ar) gas atmosphere pressure during the heat treatments) on the transport critical current densities (J c ) were investigated. The samples were characterized using X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectrometer, optical microscope, critical transition temperature and J c measurements. Response surface methodology was used to optimize the conditions for the maximum J c of the samples and to understand the significance and interaction of the factors affecting J c . 3-level-3-factor central composite design was employed to evaluate the effects of the fabrication conditions parameters such as annealing temperatures (850-950°C), annealing times (30-120 min.) and Ar pressures (1-5 bars) on J c of the samples. Based on the analysis of ridge max, the optimum fabrication conditions were as follows: annealing temperature 948°C, annealing time 58 min. and Ar pressure 3 bars.

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Effects influencing the grain connectivity in ex-situ MgB2 wires

Cited by 9 publications

References 18 publications

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Effect of cold high pressure deformation on the properties ofex situMgB₂wires

Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology

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Effects influencing the grain connectivity in ex-situ MgB2 wires

Cited by 9 publications

References 18 publications

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Peningkatan Suhu Kritis Pada Sintesis Bahan Superkonduktor Magnesium Diborida Dengan Variasi Ukuran Partikel Serbuk Mg

Effect of cold high pressure deformation on the properties ofex situMgB2wires

Optimization of fabrication conditions of MgB2/Fe superconducting tapes using response surface methodology

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Product

Resources

About

Effect of cold high pressure deformation on the properties ofex situMgB₂wires