Search

Low-temperature sintering to fabricate MgB2 is considered a promising method because it reduces the formation of MgO and reduces the grain size, thereby increasing the critical current density. Chemical doping, ball milling of precursor and modifying the Mg source in precursor for low-temperature sintering have all been carefully investigated. However, the threshold of sintering temperature have been kept near 500 °C. A new in-situ method to low-temperature sintering using Mg(BH4)2 as a precursor is presented in this paper. Mg(BH4)2 decomposes into highly reactive nanoscale Mg and B in a molar ratio of 1:2 without impurities. In this method, only 2 h of sintering at 400 °C is required to completely react Mg with B to produce MgB2, and after 54 h sintering, the sample has comparable JC to the normal MgB2 from solid-state reaction method sintered at 800 °C. The sample sintered at 500 °C give better JC than normal MgB2 under both high and low magnetic field. [ABSTRACT FROM AUTHOR]

l A sol-gel method for superconducting joints of high-performance MgB 2 films. l Two types of MgB 2 joints a two-piece-face-to-face joint, and a three-piece-bridging joints. l The joint showed a high T C of 40 K, a high I C of 340 mA at 0 T. Large-area high-quality MgB 2 thin films were needed in many superconducting applications such as superconducting radio frequency (RF) cavities. However, fabricating large films with high quality can be difficult. Thus, a jointing method between MgB 2 films can be crucial in a lot of superconducting electronic applications. In this article, we successfully fabricated superconducting joints for MgB 2 films. The sol-gel of Mg(BH 4) 2 ·Et 2 O was used as the glue. Two types of MgB 2 joints were shown in this work, a two-piece face-to-face joint, and a three-piece bridging joint. The sol-gel derived MgB 2 joints have shown very good superconducting performance, with a high superconducting critical temperature (T C) of 40 K, a high critical current (I C) of 340 mA at 0 T, and very nice current capacity in magnetic fields up to 4 T. [ABSTRACT FROM AUTHOR]

Abstract: MgB2 thin films were prepared by ex-situ annealing of Mg/B multilayers. Different precursor, substrate and annealing condition were investigated. After annealed in a flow of Mg vapor with reducing hydrogen ambient for 1–4min, high quality 20nm-thick c-oriented MgB2 thin films with and critical current density J C =2×106 Acm−2 at 30K were obtained. The mean roughness of the 20nm-thick film was 2.68nm. [Copyright &y& Elsevier]