Elastic wave velocities of high density pressure‐induced amorphous GeO 2

Two samples of amorphous GeO 2 were prepared at room temperature by compression of α ‐quartz type crystals at 13 and 20GPa. The former sample has a density of 4.42(6) Mg/m³ and the latter 5.34(2) Mg/m³. The elastic wave velocities, ν p and ν s of each sample were measured under pressures up to 4GPa at room temperature. The results are: (1) Both ν p and ν s are faster in the sample with higher density. (2) Even the velocities of the sample with lower density are faster than those of both α ‐quartz type crystal and a conventional amorphous phase whose density is less than 4Mg/m³. Since the pressure derivative of ν p is larger than that of ν s , the difference between ν p and ν s becomes greater with increasing pressure.