Pressure Derivatives of the Sound Velocities of Polycrystalline Alumina

The sound velocities and the pressure derivatives of the sound velocities were measured on a small specimen of polycrystalline alumina by the method of “pulse superposition”. The pressure derivatives found from experiments up to 4 kbars at 25°C are: image These values lead to the variation of Poisson's ratio with pressure of dσ/dP = 1.02 × 10 −4 / kbar and to the variation of (isothermal) bulk modulus with pressure of dB T /dP = 3.99. Using the above values the compression is computed up to 400 kbars and compares well with shock wave measurements. Consequently, the measured pressure derivatives may hold up to several hundred kilobars.