High Pressure Phase of MgTe: Stable Structure at STP?

Abstract

The crystal structure of MgTe has been studied in a diamond anvil cell using energy dispersive x-ray diffraction to 60 GPa at room temperature. The first pressure-induced structural phase transformation among magnesium chalcogenides was observed for MgTe at $P\ensuremath{\approx}1\ensuremath{-}3.5$ GPa. The new phase has been indexed as the NiAs structure and it persisted after unloading to low pressure (0.2 GPa) and annealing for 10 h at 100 \ifmmode^\circ\else\textdegree\fi{}C. This is the first experimental evidence consistent with a recent theoretical prediction that for low temperature the ground state of MgTe is the NiAs structure. It is also the first pressure-induced wurtzite to NiAs transition.