Pressure evolution of the cinnabar phase of HgTe.

Abstract

The first high-pressure phase of HgTe has been studied by angle-dispersive powder diffraction with an image-plate area detector and synchrotron radiation. The evolution of the full structure of the cinnabar phase has been followed over its pressure domain (from 1.5 to 8.0 GPa). The pressure evolution of atomic positions, angles, and interatomic distances are discussed. In particular, the evolution of the interatomic distances reveals the intermediate role of the cinnabar phase between fourfold and sixfold coordination in a similar way to that observed in CdTe. The Murnaghan and Birch equation of state adjusted to the data gives values of the bulk modulus considerably higher than previously published ones and closer to the average bulk modulus of cinnabar CdTe. Volume changes at the transition are 11\ifmmode\pm\else\textpm\fi{}2 % for the zinc blende to cinnabar transition and 3\ifmmode\pm\else\textpm\fi{}1 % for the cinnabar to rocksalt transition.