Phase transformation of BeS and equation-of-state studies to 96 GPa

Abstract

We report the existence of a reversible first-order phase transition of BeS from the zinc-blende structure, $B3,$ to the nickel-arsenide structure, $B8,$ at 51 GPa with a volume change of 11%. The NiAs phase remains stable up to at least 96 GPa. A second-order Birch equation describes the equation of state of the $B3$ phase with ${B}_{o}=105\mathrm{GPa}$ and ${B}_{o}^{\ensuremath{'}}=3.5.$ Preliminary studies of BeO to 66 GPa are described.