EELS studies of MgB2 superconductor obtained under high pressure

The MgB2 intermetallic superconductor obtained under high pressure, which h as the transition temperature of above 39 K, has been studied by scanning e lectron microscopy (SEM), transmission electron microscopy and parallel ele ctron energy-loss spectroscopy (EELS). From the SEM, it can be seen that th e bulk compound is highly dense and the grains are connected compactly. The size of single crystal is at the magnitude of similar to mum. The high res olution transmission electron microscopy image of [001] zone axis clearly s hows the hexagonal planes of the constituent atoms. The EELS spectrum of B shows the peaks of a and antibonding bonds. The EELS results show a good ag reement with the theoretical band structure calculations and the hole dopin g in the B sigma (P-xy) bonding bands. (C) 2001 Elsevier Science B.V. All r ights reserved.