Polymorphic Transformation in Ytterbium

Abstract

The purpose of this Letter is to report the discovery of a polymorphic transformation in Yb and to provide a brief discussion of its significance in relation to recent high-pressure studies. The transformation, $\beta \left(\mathrm{fcc}\right)\leftrightarrow \alpha \mathrm{}\left(\mathrm{hcp}\right)\mathrm{}$, is martensitic, the $\alpha$ phase being the stable form at 1 atm below ∼270°K. The slope of the $\frac{\alpha }{\beta }$ equilibrium boundary, ${\left(\frac{d{T}_{\alpha ,\beta }}{\mathrm{dP}}\right)}_{{270}^{\circ },1\mathrm{} \mathrm{atm}}$, is (-23±8)°K/kbar.