IRREGULARITIES OF YTTERBIUM UNDER HIGH-PRESSURE

Phase transitions of the rare-earth metal ytterbium were studied under pressure up to 70 GPa at room temperature with an energy-dispersive x-ray-diffraction technique using synchrotron radiation. A new phase transition hcp-->fcc(II) was observed at 57 GPa. The phase sequence with pressure up to 70 GPa is fcc(I)-->bcc-->hcp-->fcc(II). The hcp and fcc(II) phases show some similarity in their compression behavior to the lower pressure phases of praseodymium which is considered as first evidence for a strong hybridization between f electrons and conduction electrons.