Control of the Critical Current Density Through Microstructural Design by Ho2O3 and Te Co-addition into MgB2 Processed by Ex Situ Spark Plasma Sintering

Badica, P.; Aldica, G.; Burdusel, M.; Grigoroscuta, Mihai Alexandru; Ionescu, A.; Sandu, V.; Popa, S.; Enculescu, Monica; Pasuk, Iuliana; Kuncser, Andrei

doi:10.1007/978-3-030-23303-7_11

Cited by 2 publications

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“…A decrease from 2.8 to 0.8 T is also visible for μ 0 H cross . The values of p 1 (∼1.7) and q 1 (4.6-5.9) and variation of the latter parameter with temperature are approximately similar to those reported in [43] for the composite non-machinable samples with starting compositions ((MgB 2 ) 0.99 (Te x (HoO 1.5 ) y ) 0.01 ), x/y=0.31/0.69, 0.25/0.75. On the other hand, the values of p 2 (∼−0.6) and q 2 (∼2.1) and variation of these parameters with temperature is very different than for the indicated samples: the dependencies p 2 (T) and q 2 (T) for MgB 2 samples co-added with Ho 2 O 3 and Te show a higher degree of complexity and, hence, of pinning behaviour.…”

Section: Critical Temperature Critical Current Densities and Pinning ...supporting

confidence: 85%

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder

Gozzelino

Gerbaldo

Ghigo

et al. 2020

Supercond. Sci. Technol.

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Superconductors are key materials for shielding quasi-static magnetic fields. In this work, we investigated the shielding properties of an MgB 2 cup-shaped shield with small aspect-ratio of height/outer radius. Shape and aspect-ratio were chosen in order to address practical requirements of both high shielding factors (SFs) and space-saving solutions. To obtain large critical current densities (J c ), which are crucial for achieving high magnetic-mitigation performance, a highpurity starting MgB 2 powder was selected. Then, processing of the starting MgB 2 powder into high density bulks was performed by spark plasma sintering. The as-obtained material is fully machinable and was shaped into a cup-shield. Assessment of the material by scaling of the pinning force showed a non-trivial pinning behaviour. The MgB 2 powder selection was decisive in enlarging the range of external fields where efficient shielding occurs. The shield's properties were measured in both axial-and transverse-field configurations using Hall probes. Despite a height/outer radius aspect ratio of 2.2, shielding factors higher than 10 4 at T=20 K up to a threshold field of 1.8 T were measured in axial-field geometry at a distance of 1 mm from the closed extremity of the cup, while SFs>10 2 occurred in the inner half of the cup. As expected, this threshold field decreased with increased temperature, but SFs still exceeding the above mentioned values were found up to 0.35 T at 35 K. The shield's shape limits the SF values achievable in transverse-field configuration. Nevertheless, the in-field J c of the sample supported SFs over 40 at T=20 K up to a field of 0.8 T, 1 mm away from the cup closure.

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Section: Critical Temperature Critical Current Densities and Pinning ...supporting

confidence: 85%

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder

Gozzelino

Gerbaldo

Ghigo

et al. 2020

Supercond. Sci. Technol.

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On the pinning force in high density MgB2 samples

Sandu

Ionescu

Aldica

et al. 2021

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An analysis of the field dependence of the pinning force in different, high density sintered samples of MgB2 is presented. The samples were chosen to be representative for pure MgB2, MgB2 with additives, and partially oriented massive samples. In some cases, the curves of pinning force versus magnetic field of the selected samples present peculiar profiles and application of the typical scaling procedures fails. Based on the percolation model, we show that most features of the field dependence of the critical force that generate dissipation comply with the Dew-Hughes scaling law predictions within the grain boundary pinning mechanism if a connecting factor related to the superconducting connection of the grains is used. The field dependence of the connecting function, which is dependent on the superconducting anisotropy, is the main factor that controls the boundary between dissipative and non-dissipative current transport in high magnetic field. Experimental data indicate that the connecting function is also dependent on the particular properties (e.g., the presence of slightly non-stoichiometric phases, defects, homogeneity, and others) of each sample and it has the form of a single or double peaked function in all investigated samples.

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Control of the Critical Current Density Through Microstructural Design by Ho2O3 and Te Co-addition into MgB2 Processed by Ex Situ Spark Plasma Sintering

Cited by 2 publications

References 25 publications

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder

On the pinning force in high density MgB2 samples

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Control of the Critical Current Density Through Microstructural Design by Ho2O3 and Te Co-addition into MgB2 Processed by Ex Situ Spark Plasma Sintering

Cited by 2 publications

References 25 publications

High magnetic shielding properties of an MgB2 cup obtained by machining a spark-plasma-sintered bulk cylinder

High magnetic shielding properties of an MgB2 cup obtained by machining a spark-plasma-sintered bulk cylinder

On the pinning force in high density MgB2 samples

Contact Info

Product

Resources

About

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder

High magnetic shielding properties of an MgB₂ cup obtained by machining a spark-plasma-sintered bulk cylinder