Enhanced critical current density at high magnetic fields in MgB2 wire processed by in-situ spark plasma sintering

Abstract Sparking plasma sintering (SPS) technique has the characteristics of rapid heating and cooling rate, high mass density, and grain activation sintering. Therefore, it may be used to improve the grain connection, refine the grains, and enhance the superconducting current-carrying capacity of MgB2. In this paper, the MgB2 wire prepared by the in-situ method is rapidly treated by the SPS method, and the effects of different SPS sintering conditions on the phase formation, microstructure characteristics and superconductivity of the MgB2 material are studied, and compared with the MgB2 prepared by conventional sintering and the ex-situ SPS method. It was found that the SPS-treated samples were in a rapidly changing non-equilibrium state during the entire sintering process, so there are existing both flake particles and nanoparticles in the samples, which significantly improves the connection of the grains and refine the grains, resulting in significantly improved superconducting performance for MgB2. The critical current density Jc of SPS-treated sample at 850 ℃ reached 1354 A/cm2 @ (10 K, 5 T) and 1615 A/cm2 @ (20 K, 3 T), which were 3.7 times and 2.6 times that of conventional sintering sample. Our research shows that SPS is an effective method to improve the superconductivity of in-situ MgB2 wire.