Min Pan

Stability of concentration-related self-interstitial atoms in fusion material tungsten*

Based on the density functional theory, we calculated the structures of the two main possible self-interstitial atoms (SIAs) as well as the migration energy of tungsten (W) atoms. It was found that the difference of the 〈110〉 and 〈111〉 formation energies is 0.05–0.3 eV. Further analysis indicated that the stability of SIAs is closely related to the concentration of the defect. When the concentration of the point defect is high, 〈110〉 SIAs are more likely to exist, 〈111〉 SIAs are the opposite. In addition, the vacancy migration probability and self-recovery zones for these SIAs were researched by making a detailed comparison. The calculation provided a new viewpoint about the stability of point defects for self-interstitial configurations and would benefit the understanding of the control mechanism of defect behavior for this novel fusion material.

SmBa2Cu3O7−δ superconducting layer prepared on NiO buffer layer through fluorine-free chemical method

With energy shortage becoming increasingly severe, the application of high-temperature superconducting material is a considerable prospects, where economic, efficient and energy-saving preparation technology becoming the key factors for the large-scale applications of REBa2Cu3O7−δ (REBCO) superconducting coated conductors. Currently, non-vacuum chemical solution deposition technique is an important way to reduce the cost of preparation of coated conductors. However, a randomly oriented NiO growth is an important problem for the non-vacuum chemical preparation of superconducting coated conductor. A simple and valid method is to prepare textured NiO film on the bare nickel (Ni) tape. In this paper, NiO films with c-axis texture were prepared in air and in argon respectively by the surface oxidation epitaxial method. We obtained the smooth and densification NiO films. The layer of SmBa2Cu3O7−δ was fabricated on the NiO film via a fluorine-free chemistry method. The purpose of this paper is to provide a potential value of non-vacuum chemical solution deposition technique for preparation of REBCO superconducting coated conductors.