Fabrication of superconducting magnesium diboride thin films by electron beam annealing

Abstract

The technique of electron beam annealing for fabricating MgB2 thin films has been explored. MgB2 thin films were prepared by e-beam evaporation of M–B precursor films on 6H–SiC (0001) substrates followed by ex situ electron beam annealing without any extra Mg vapor or argon gas protection. The very short annealing duration, about 1 s, effectively prevented volatilization and oxidation of Mg and decomposition of MgB2. In comparison with the MgB2 thin films grown by other techniques, our films show medium qualities including a superconducting transition temperature of Tconset ∼ 35.3 K, a transition width ΔTc ∼ 0.2 K, and a critical current density of Jc(5 K, 0 T) ∼ 3.2 × 106 A cm − 2. Such an electron beam annealing technique has potential for the fabrication of large-scale MgB2 thin films as well as MgB2 wires and tapes.

Elimination of bubbles and improvement of the superconducting properties in MgB2films annealed using electron beam

“…Although smooth films can be achieved by post-annealing methods, the above three post-annealing cases require a long time and need atmospheric protection. Therefore, electron-beam annealing [19,20] may be the optimal method for fabricating smooth MgB 2 thin films. Our group [19,20] have fabricated MgB 2 films using this method.…”

“…Therefore, electron-beam annealing [19,20] may be the optimal method for fabricating smooth MgB 2 thin films. Our group [19,20] have fabricated MgB 2 films using this method. It requires no Ar or Mg vapour protection and the annealing duration is several seconds, which can effectively reduce the volatilization of Mg in the precursor film.…”

Magnesium Diboride Superconducting Films Synthesized by Different Electron-Beam Annealing Currents

“…Therefore, this method brings considerable inconvenience to the actual operation and large-scale production. In order to overcome the above disadvantages, our group provided a new annealing method, which is called electron beam annealing (EBA) [21][22][23] . Because of short heating and cooling time, MgB 2 can't be decomposed easily.…”

Influence of Electron-Beam Annealing Duration on MgB₂ Film Superconductivity

“…In spite of the outstanding superconducting properties of the MgB 2 films prepared by hybrid physical-chemical vapor deposition (HPCVD) [7][8][9][10], flammable, explosive, poisonous and expensive diborane (B2H6) gas must be used in the HPCVD method. In order to overcome or improve the shortcomings mentioned above, the effective electron beam annealing (EBA) method was first presented in June, 2011 by our group [14,15], in which the electron beam is used to irradiate Mg-B multilayer films to make Mg combine with B to form MgB 2 phase in a few seconds or sub-seconds without the use of the expensive B2H6, extra Mg vapor and argon gas. The very short annealing duration can limit the loss of Mg from the precursors, the reaction of Mg with other substances and the decomposition of MgB 2 , and this is favourable toward the fabrication of high-quality MgB 2 thin film and thick films.…”