Pressure-induced structural changes in liquid Ge₃₃Te ₆₇ and liquid Ge₁₅Te₈₅

We have performed energy-dispersive X-ray di.raction measurements for liquid Ge₃₃Te₆₇ up to 9 GPa and observed a pressure dependence of the structure for the first time. We confirmed that the structure is diferent from the Ge(Te_1/2)₄ tetrahedral network in any pressure at the temperature higher than 740 °C. We observed a small expansion in the bond length with increasing pressure up to 2.4 GPa. We also investigated the pressure dependence of the structure of liquid GGe ₁₅Te₈₅ at constant temperature at around 730 °C. The pressure dependence was found to be similar to that of liquid Ge ₃₃Te₆₇, i.e., we confirmed that the structure is different from the tetrahedral network in this high temperature. Although the structure at 730 °C at ambient pressure is regarded as a "densely packed" structure in comparison to the lower-temperature structure, we clarified that the structure is still highly compressible.