Superior critical current density obtained in Mg11B2 low activation superconductor by using reactive amorphous 11B and optimizing sintering temperature

Abstract

. (2015). Superior critical current density obtained in Mg 11 B 2 low activation superconductor by using reactive amorphous 11 B and optimizing sintering temperature. Journal of Alloys and Compounds, Superior critical current density obtained in Mg11B2 low activation superconductor by using reactive amorphous 11B and optimizing sintering temperature AbstractThe un-doped Mg 11 B2 and Cu-doped Mg 11 B2 bulks using 11 B as a boron precursor were fabricated by solidstate reaction and sintered at different temperature in present work. By analyzing the sintering process, it was found that 11 B original powder is more reactive and can react with Mg severely even at low temperature before Mg melting, which leads to the formation of refined Mg 11 B2 grains. Consequently, the critical current density of Mg 11 B2 sample prepared in this work is higher than that of natural MgB2. Furthermore, it was found that proper Cu addition could obviously accelerate the reaction between Mg and 11 B and promote the formation of Mg 11 B2 due to the appearance of Mg-Cu liquid at low sintering temperature before Mg melting. On the other hand, Cu addition also introduced more MgCu 2 impurity, leading to a relatively lower critical current density on the whole. Interestingly, the critical current density of the Cu doped sample sintered at 800 °C is surprisingly enhanced at the low field, compared with that of the corresponding un-doped one. This is due to the peritectic reaction which generated small-sized MgCu 2 occurred that at 800 °C, providing MgCu 2 pinning centers well-distributed in the MgB2 matrix. On the other hand, Cu addition also introduced more MgCu 2 impurity, leading to a relatively lower critical current density on the whole. Interestingly, the critical current density of the Cu doped sample sintered at 800 o C is surprisingly enhanced at the low field, compared with that of the corresponding un-doped one. This is due to the peritectic reaction which generated small-sized MgCu 2 occurred that at 800 o C, providing MgCu 2 pinning centers well-distributed in the MgB 2 matrix.

Doping-Induced Isotopic Mg11B2 Bulk Superconductor for Fusion Application

“…suggested that the 11 B accelerated the Mg-B solid-solid reaction below 650 °C [28]. Hence, the MgO particles were mostly included in the growing MgB2 grains instead of aggregating at the boundary.…”

“…Combined with the distribution of Mg element, the MgO phase was believed to be dispersed homogeneously on the matrix rather than gathered in the hole, which implied good MgB 2 grain connectivity. A thermodynamic calculation has demonstrated that the MgO phase was formed prior to MgB 2 , and the study on undoped Mg 11 B 2 suggested that the 11 B accelerated the Mg-B solid-solid reaction below 650 • C [28]. Hence, the MgO particles were mostly included in the growing MgB 2 grains instead of aggregating at the boundary.…”

Measurement of Mechanical Behavior of 11B-Enriched MgB2 Wire Using a Pulsed Neutron Source

“…Among these materials, 10 B has been identified as prone to decomposing into Li and He gases through nuclear reactions with neutrons. To circumvent this issue, research efforts are underway to develop superconductors with 11 B substitutions [13][14][15]. The 10 B isotope exhibits a substantial neutron absorption cross-section [16], rendering materials containing boron challenging to assess using neutron scattering.…”