High-pressure and high-temperature synthesis of MgB2 and its superconductivity

The single-phase sample of MgB₂ was prepared successfully at the temperature of 900°C and under the pressure of 3 GPa. The structure of the sample was investigated using powder X-ray diffraction and Rietveld analysis. The results show that the structure of the sample belongs to the hexagonal structure with space group of P6/mmm, a=3.0861(5) Å, c=3.5222(8) Å. The magnetic and resistance measurements indicate that the superconducting transition temperature T_c is 39 K.