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Kong X.,CAS Institute of Electrical Engineering | Kong X.,Beijing Key Laboratory of Bioelectromagnetics | Dai Q.,Peking University | Han L.,CAS Institute of Electrical Engineering | And 8 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2012

Here, we addressed the feasibility of depositing the superconducting MgB 2 thin films by electron beam annealing. Based on the theoretical simulation, the MgB 2 thin films were grown. In the newly-developed technique, the precursor films, with a multilayered structure of [B(10 nm)/Mg(15 nm)] 4/SiC were annealed by ex situ electron beam annealing, in the lab-built, electron-beam heating set-up, under the following conditions: a pressure of 5.0×10 -3 Pa, an electron beam accelerating voltage of 40×10 3 V, a beam current of 2×10 -3 A, a beam diameter of 14.2 mm, and an annealing time for 1.5 s. The microstructures and phase structures of the electron beam annealed films were characterized with X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results show that the fairly smooth and compact MgB 2 films display good superconducting properties, including a zero-resistance temperature ~30.3 K, a transition width ΔT c~0.4 K, and a critical current density of Jc(5 K, 0 T)~5.0×10 6 A/cm 2. We suggest that it be feasibly to fabricate large-area MgB 2 films, as well as MgB 2 wires and MgB 2 tapes, by electron beam annealing.


Kong X.,CAS Institute of Electrical Engineering | Kong X.,Beijing Key Laboratory of Bioelectromagnetics | Dai Q.,Peking University | Han L.,CAS Institute of Electrical Engineering | And 9 more authors.
Materials Science Forum | Year: 2013

A novel method to fabricate Magnesium diboride (MgB2) film by electron beam annealingwas presented. The MgB2 thin films could be prepared in a second or sub-second without any toxicdiborane gas, extra Mg vapor or argon gas. The method has the advantages of short formation timeand high efficiency. Based on this, the relationship between MgB2 conductivity and electron beamannealing duration was investigated experimentally with an accelerating voltage of 40 × 103 V, abeam current of 3×10-3 A and different annealing durations of 0.1796s, 1860s, 0.2108s, 0.2200s and0.2332s. The experimental results showed the MgB2 film with 0.2200s has the highest Tc onset, themost dense structure and the strongest diamagnetic signal. Its zero-field Jc at 5 K was 5.0 × 106A/cm2. Also the variation of the film superconducting properties with the annealing duration wasfound, it will provide an important reference for the preparation of high-quality MgB2 thin films. © (2013) Trans Tech Publications, Switzerland.

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