Pressure-induced polyamorphic transitions in ytterbium-based bulk metallic glasses

• The positions of the FSDP (q1) are increasing and scale with pressure.
• The variations of reduced volume ratio and bulk modulus under pressure were analyzed.
• The results indicate that polyamorphic transition occurs during pressure progress.
• The delocalization of 4f electrons is responsible for the polyamorphic transition.

The structure of Yb60Ca2.5Zn20Mg17.5 bulk metallic glasses was investigated by in situ angle-dispersive X-ray diffraction with a synchrotron radiation source. The glassy nature of the samples was stable up to ~30 GPa at room temperature. The volume and bulk modulus as a function of hydrostatic pressure were extracted from the diffraction data. A sudden change was observed in the volume and bulk modulus during compression. Results indicated that pressure induced polyamorphic phase transition in Yb-based bulk metallic glasses compared with Pr- and Gd-based bulk metallic glasses. The critical pressure of the transition was about 10 GPa. The delocalization of 4f electrons under high pressures was responsible for the amorphous-to-amorphous phase transition in Yb-based bulk metallic glasses.