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MgB 2 /BN/MgB 2 trilayer films have been fabricated by using hybrid physical–chemical vapor deposition (HPCVD) method for the MgB 2 layers and chemical vapor deposition (CVD) method for the BN layers in the same reactor. The films are studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and magnetization measurements. These test outcomes indicate the trilayer films are grown without deteriorating the superconductivity of MgB 2 films. Our results show that it is feasible to grow MgB 2 /BN/MgB 2 trilayer films in the same reactor sequentially, which has the advantage of reducing contamination during the growth. This therefore opens the door for fabricating all-MgB 2 Josephson junctions by using the BN film as the insulating layer. [ABSTRACT FROM AUTHOR]

MgB 2 has shown great potential in making medium strength superconducting magnet using electronic refrigeration without liquid helium. One of the major problem in building the MgB 2 superconducting magnet is the joints in the coils. An effective method of building a superconducting joint is crucial. In this work, we have demonstrated a novel process of building a superconducting joint utilizing sol-gel method. Two HPCVD MgB 2 thin film on SiC substrate is pasted face-to-face with Mg(BH 4 ) 2 •Et 2 O gel. After annealing in Mg vapor, Mg(BH 4 ) 2 •Et 2 O gel decomposed and turned to MgB 2 superconducting joint. The joint showed good connectivity between the two films and has a good T C of 34 K. Infield measurement of the joint showed that the joint work well at 20 K with the applied magnetic field up to 4 T. [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]