A sol–gel method for growing superconducting MgB<sub>2</sub>films

Chen, L P; Zhang, Cenai; Wang, Y B; Feng, Qing Rong; Gan, Zizhao; Yang, Jinbo; Li, X G

doi:10.1088/0953-2048/24/1/015002

“…Near zero applied field, it is shown that the J c is in the range 1.2 − 2.6 × 10 6 A cm −2 at temperatures 5-25 K, with the value 1.7 × 10 6 A cm −2 at 5 K-10 K lower than 2.6 × 10 6 A cm −2 at 15 K because of the suppression from flux jumps at 5-10 K as exemplified in the inset of figure 10(a) [52]. We note that these J c values are lower than the superior values of above 10 7 A cm −2 for high-quality epitaxial MgB 2 thin films [36,67], but comparable to both typical values for epitaxial MgB 2 films [68] and that reported on high-quality polycrystalline MgB 2 planar films [33,36,69]. According to previous simulations [18,19,26], these values of J c would be promising for potential applications in ICF.…”

Section: Superconducting Transitionsupporting

confidence: 71%

Properties of superconducting MgB₂ spherical shells deposited on 2 mm and 1 mm diameter Si₃N₄ spheres

Xu¹,

Sun²,

Zhao³

et al. 2023

Supercond. Sci. Technol.

1

0

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Superconducting spherical shells may not only provide an appealing platform for exploring superconductivity in three-dimensional (3D) geometries with curved surfaces, but also be practically applied in important fields, such as in gyroscopes and gravimeters. In inertial confinement fusion (ICF), the perturbation on the target capsule caused by traditional contact support methods is recognized as one of the major contributors to performance degradation in ICF implosions. It was proposed recently that coating the capsule with a thin superconducting MgB2 spherical shell to realize non-contact support by means of magnetic levitation at the required temperatures ∼ 20 K might offer a promising solution to this longstanding problem. To simulate the coating of ICF capsules, we deposited MgB2 spherical shells onto polycrystalline Si3N4 spheres (diameter d = 2 mm and 1 mm) via a hybrid physical–chemical vapour deposition technique. For both diameters, the spherical shells, of about 1 µm in thickness and covering the whole spheres completely, were polycrystalline with thin plate-shaped MgB2 crystallites oriented randomly and closely connected. The spherical shells exhibited superconducting transition at a zero resistance temperature T c z e r o of 38.5–39.4 K in four-probe resistance measurements and ideal diamagnetism at low temperatures in magnetization measurements, suggesting the good crystallinity and homogeneity of the shells. The upper critical field H c 2 , the irreversibility field H i r r and the lower critical field H c 1 were characterized and showed similar magnitudes and temperature dependencies for the d = 2 mm and 1 mm shells, yielding H i r r of 7–8 T and H c 1 of 7–12 mT at 20 K. The superconducting critical current density J c values, evaluated from the magnetization hysteresis loops, were 1.8 × 10 6 A cm−2 and 8.5 × 10 4 A cm−2 at 20 K under zero and 2 T applied field, respectively, for the d = 1 mm shell. The occurrence of small flux jumps was observed at low temperatures up to 12 K and in low fields below 0.3 T. The results demonstrate the feasibility of fabricating MgB2 spherical shells with properties applicable to potential areas employing magnetic levitation such as in ICF and that MgB2 spherical shells may be exploited as an experimental system to study superconductivity in 3D curvilinear geometry.

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“…Mg(BH 4 ) 2 •Et 2 O gel was obtained by the chemical reaction in diethyl ether as follows. This detailed fabrication method of Mg(BH 4 ) 2 has been introduced in the previous paper [24].…”

Section: Methodsmentioning

confidence: 99%

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites

Luo

¹

,

Zi-Geng

²

,

Cai

³

et al. 2019

Supercond. Sci. Technol.

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Practical applications of the MgB 2 prepared by the in situ method are usually limited because of the pores formed by the volatility of Mg. In order to improve the performance of MgB 2 bulks, MgB 2 bulks were fabricated through an in situ synthesis method with composites of B powder, Mg powder, and 10-100 wt% Mg(BH 4 ) 2 powder. The superconducting properties and grains structure of these MgB 2 bulks were investigated, such as onset superconducting transition temperature (T c ), critical current density (J c ), porosity, resistivity (ρ), and grain connectivity. For the MgB 2 bulk prepared from 80 wt% Mg(BH 4 ) 2 powder added composites, the J c (1 T) value at 5 K was 4.1×10 5 A cm −2 and the onset T c value was 37.5 K. Moreover, the microstructure of these MgB 2 bulks was also analyzed using scanning electron microscope (SEM). The MgB 2 bulk with less pores can be prepared with moderate Mg(BH 4 ) 2 powder added composite as precursor. The composites also provide raw materials for preparing high-quality in situ MgB 2 superconducting wires. Keywords: Mg(BH 4 ) 2 , MgB 2 , composite precursor, porosity, high J c

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“…The principal driving force for EPD is the charge on the particle and the electrophoretic mobility of the particles in the solvent under the influence of an applied electric field. The EPD technique has been used successfully for thick film of silica (Sarkar and Nicholson, 1996;Besra, 2007), nanosize zeolite membrane (Shan et al, 2004), hydroxyapatite coating on metal substrate for biomedical applications (Zykova et al, 2015), luminescent materials (Meng, 2013), high-temperature superconducting (HT C or HTS) films (Chen et al, 2011), gas diffusion electrodes and sensors (Bodansky and Latner, 1972), multi-layer composites (Boccaccini et al, 2010), glass and ceramic matrix composites by infiltration of ceramic particles onto fibre fabrics (Boccaccini and Trusty, 1998), oxide nanorods (Cao, 2004), carbon nanotube film (Chen et al, 2012), functionally graded ceramics (Sarkar and Nicholson, 1996), layered ceramics (Yang et al, 2011), superconductors, piezoelectric materials (Besra, 2007, etc. Indeed, the only intrinsic disadvantages of EPD, compared with other colloidal processes (e.g.…”

Section: Electrophoretic Depositionmentioning

confidence: 99%

A Tracking Review on Non Arc Melting Processes for Improved Surface Properties in Metallic Materials

2021

CMR

0

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Most metallic materials lack the adequate surface characteristics to satisfactorily perform intended service functions. In such instance, the surface properties are modified by altering the chemistry, structure and/topology of the top surface of the surface via modification techniques. There exists wide options of techniques for modifying the surface properties and these are well documented in the literature. However, these techniques have different scientific underpinnings controlling them such that it is difficult to use a single mechanism to characterize the techniques. Arising from this, it is imperative that a holistic understanding of the various processes is provided. Therefore, in this paper, research status on the wide range of non-melting technique for surface modification is presented. The presentation discusses the investigation conducted on the various nonsurface melting techniques and provides a comparison across the techniques. Recent developments in these techniques are equally presented. Existing challenges and emerging trends in the field are also highlighted. .

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A sol–gel method for growing superconducting MgB₂films

Cited by 16 publications

References 36 publications

Properties of superconducting MgB₂ spherical shells deposited on 2 mm and 1 mm diameter Si₃N₄ spheres

Properties of superconducting MgB₂ spherical shells deposited on 2 mm and 1 mm diameter Si₃N₄ spheres

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites

A Tracking Review on Non Arc Melting Processes for Improved Surface Properties in Metallic Materials

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A sol–gel method for growing superconducting MgB2films

Cited by 16 publications

References 36 publications

Properties of superconducting MgB2 spherical shells deposited on 2 mm and 1 mm diameter Si3N4 spheres

Properties of superconducting MgB2 spherical shells deposited on 2 mm and 1 mm diameter Si3N4 spheres

Microstructure and superconducting properties of MgB2 bulks prepared from Mg + B + Mg(BH4)2 composites

A Tracking Review on Non Arc Melting Processes for Improved Surface Properties in Metallic Materials

Contact Info

Product

Resources

About

A sol–gel method for growing superconducting MgB₂films

Properties of superconducting MgB₂ spherical shells deposited on 2 mm and 1 mm diameter Si₃N₄ spheres

Properties of superconducting MgB₂ spherical shells deposited on 2 mm and 1 mm diameter Si₃N₄ spheres

Microstructure and superconducting properties of MgB₂ bulks prepared from Mg + B + Mg(BH₄)₂ composites