Ultrasonic Properties of the MgB₂ Superconductor

The sound velocities of longitudinal and shear waves are measured on polycrystalline MgB₂ superconductor with T_c of 39K. The specimen used in the experiments is pressed and heated using the MgB₂ powder. The elastic moduli, Debye temperature and specific heat at room temperature are obtained based on sound velocity data. The results indicate that the velocities are much higher than those in the usual materials, while elastic constants remain reasonably soft, which may be due to the high transition temperature of the MgB₂ superconductor.