Elastic Behaviour of the Gadolinium Gallium Garnet Crystal under High Pressure

By means of the pulse echo overlap method, we have measured the velocities of ultrasonic wave propagating along different crystalline axes of the Gadolinium Gallium Garnet crystal (GGG). We have also measured the changes of the velocities with hydrostatic pressures and uniaxial stresses respectively. The second and third order elastic constants of GGG are obtained as follows: c11=3.04, c12=1.31, c44=0.94, c111=-17.97, c112=-12.86, c123=-1.06, c144=-2.11, c166=-3.29 and c456=-0.94, where the unit is 1011 N/m2. From these date we have calculated the Debye temperature and Gruneisen parameters (p,N) of GGG crystal from [011] to [111], [110] and [100].