Structural and electronic transitions in ytterbium metal to 202 GPa

Ytterbium (Yb), a member of the rare earth group metals with a filled f shell and a divalent electronic character, has been studied under static high pressures in a diamond anvil cell to 202 GPa. We report a new transformation from a face-centered-cubic structure to a hexagonal phase with 3 atoms/cell (space group P3(1)21 referred to as hP3) at 98 +/- 5 GPa. This hP3 phase is similar to that observed in trivalent neodymium and samarium at pressures near 40 GPa. Our high pressure study thus clearly demonstrates that Yb is no longer an "irregular" member of the rare earth metals, and divalent to trivalent electronic transition is completed at megabar pressures.