In previous studies, we found that bulk MgB2 contained numerous voids in various shapes and sizes. With the aim of improving the critical current density as well as the mechanical performance of the disk-shaped MgB2 bulk superconductors, we added Ag and optimized the processing conditions. The samples with varied Ag content from 0, 2, 4, 6, to 10wt% were synthesized in pure Ar atmosphere. Microstructural observation by scanning electron microscopy confirmed that metallic Ag particles are embedded in the void regions. Furthermore, atomic force microscopy indicated that silver-based MgB2 particles are of nanometer size. As a result, the critical current density (J c) values were improved with Ag addition as compared to pure MgB2 bulk. The sample with 4wt% Ag addition exhibited the highest J c of 293kA/cm2 at 20K and self field. The respective J c values at 10K were 400kA/cm2, 300kA/cm2, and 100kA/cm2 in self field, 1T and 2T. These values are the highest record values so far reported in bulk MgB2 materials.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Energy Engineering and Power Technology
- Electronic, Optical and Magnetic Materials