Structural and Electronic Transitions in Ytterbium Metal to 202 GPa

Abstract

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 $\mathrm{hP}3$) at $98\ifmmode\pm\else\textpm\fi{}5\mathrm{GPa}$. This $\mathrm{hP}3$ 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.