Microstructure of the highly dense MgB2 Superconductor by TEM

The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure of ∼ 3 GPa was investigated by using a highresolution transmission electron microscope (HRTEM). The TEM images did not show any pores in the specimen. All grains were compactly connected, and no discernable empty spaces or impurities at the boundaries existed over the regions investigated. The HRTEM image showed clearly each constituent atom that formed the basal hexagonal plane, without any defect in a single grain. The a-axis lattice parameter, 0.307 nm, from this direct measurement ∗Correspondence should be addressed to Gun Yong Sung (e-mail: [email protected] )