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.