Abstract :
We report the high-pressure synthesis of novel superconductor MgB2 and some related compounds. The superconducting transition temperature of our samples of MgB2 is found to be 36.6 K. The MgB2 lattice parameters determined via X-ray diffraction are in excellent agreement with results of our ab initio calculations. The TDPAC measurements of 111Cd quadrupole frequency νQ demonstrate a small increase in νQ with decreasing temperature from Troom to THe. The electric field gradient Vzz at the B site calculated from first principles is in fair agreement with Vzz obtained from 11B NMR spectra of MgB2 reported in the literature. It is also very close to Vzz found in our 111Cd TDPAC experiments, which suggests that the 111Cd probe substitutes for boron in the MgB2 lattice.
