Improved Superconducting properties in the Mg11B2 low activation superconductor prepared by low-temperature sintering

Abstract

Mg11B2 has a great application prospect in the superconducting coils for fusion reactor as the “low activation superconductors”. The un-doped Mg11B2 and Cu-doped Mg11B2 bulks using 11B as a boron precursor were fabricated by low-temperature sintering in present work. It was found that the prepared Mg11B2 low activation superconductors exhibit better Jc performance than all of other Mg11B2 samples reported in previous studies. As for Cu doped Mg11B2, minor Cu addition can obviously improve the Mg11B2 grain crystallization and reduce the amount of MgO impurity. Hence, improved grain connectivity and higher Jc at low fields is obtained in Cu doped Mg11B2 samples. For un-doped samples, refined grains and more MgO impurity with proper size brought about more flux pinning centers, resulting in better Jc performance at high fields.

Improved Off-State Leakage Current and Cutoff Frequency for AlGaN/GaN HEMT by Using Silicon-on-Insulator

“…The stress in the GaN channel (σ xx ) is calculated from the Raman wavenumber shift using σ xx = Δω/k, where k = 4.3 represents the pressure coefficient. 15 As compared to the stress-free peak position of GaN at 567.5 cm −1 , 15 the in-plane stress is found to be −0.33 GPa and −0.09 GPa for GaN film grown on HR-Si and SOI, respectively. The GaN film grown on SOI substrates show a 0.24 GPa reduction in stress as compared to HR-Si due to the thinner silicon active layer over the softer SiO 2 interlayer of the SOI template, attributing to the reduction of the impact on wafer bowing and stress in GaN epilayer.…”

Evaluation of isotopic boron (11B) for the fabrication of low activation Mg11B2 superconductor for next generation fusion magnets

“…However, the critical current density (J c ) is of the most importance in the performance characteristics of our Mg 11 B 2 wires. In our previous study, 48,49,50 we synthesized Mg 11 B 2 using the same 11 B (P) powder and systematically studied the sintering process and critical current density of low activation Mg 11 B 2 superconductors in bulk and wire form. It is of interest to compare the achieved J c in our samples with the best reported results.…”

Evaluation of residual stress and texture in isotope based Mg11B2superconductor using neutron diffraction

“…[19][20][21] In contrast, 11 B is stable in the presence of neutron irradiation without an (n, a) reaction and can reduce nuclear heating. 22,23 Therefore, 11 B isotope based Mg 11 B 2 superconductor is the most desirable, if not absolutely necessary, material for Tokamak type magnets in fusion reactors.…”